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Item 3a. Study Session - Receive an update on the Sustainable Groundwater Management Act Groundwater Sustainability Plan
Council- Report Item 3a Department: Utilities Cost Center: 6001 For Agenda of: 7/20/2021 Placement: Study Session Estimated Time: 90 Minutes FROM: Aaron Floyd, Utilities Director Prepared By: Mychal Boerman, Utilities Deputy Director - Water SUBJECT: STUDY SESSION: RECEIVE AN UPDATE ON THE SUSTAINABLE GROUNDWATER MANAGEMENT ACT GROUNDWATER SUSTAINABILITY PLAN RECOMMENDATION Acting as the City of San Luis Obispo Groundwater Sustainability Agency, receive an update on the Sustainable Groundwater Management Act (SGMA) required Groundwater Sustainability Plan (GSP) development, and provide input, as necessary. :74101:i0IZE 1N142 The City and County of San Luis Obispo are working in collaboration to produce a Groundwater Sustainability Plan (GSP) to address the long-term and sustainable management of the San Luis Valley Groundwater Basin (SLO Basin). While not currently dependent on groundwater, the utilization and proper management of available groundwater resources is an important role in the further diversification and expansion of the City's water supply in the face of the coming impacts of climate change. The ten -chapter draft GSP identifies the agencies responsible for sustainable groundwater management within the SLO Basin, as well as the users and beneficiaries of groundwater within the basin. The plan also describes the land -uses and hydrologic and geologic characteristics of the basin. The GSP identifies specific areas within the SLO Basin where there is an ongoing imbalance of groundwater pumping and groundwater recharge. Areas of the SLO Basin within City limits are shown to have stable groundwater levels while areas outside of City limits, within the Edna Valley, have continually declining groundwater levels, indicative of an imbalance of groundwater supply and demand due to the pumping and recharge imbalance. In addition to discussing basin characteristics, the GSP also defines groundwater sustainability metrics for the SLO Basin and the actions that the City and County must take to ensure the basin is utilized in a sustainable manner. These measures include ongoing monitoring of groundwater wells and surface water flow, identification of water supply augmentation projects, and pumping reductions. Page 11 of 1183 Item 3a A final copy of the SLO Basin GSP is scheduled to be brought before the City Council for adoption on December 7, 2021. The purpose of this Study Session is to allow the City Council to provide input on the draft document so that comments and/or direction can be provided for the final GSP. DISCUSSION A quick reference guide of terms and definitions related to this report and the Sustainable Groundwater Management Act can be found in Attachment A — Terms and Definitions. Background: SGMA Timelines & Governance Structure 1. State of California Required`r Management of High Priority Basins The Sustainable Groundwater Management Act SGMA requires sustainable groundwater management in all high and medium priority groundwater r fa basins. The San Luis Obispo Valley } °' , Groundwater Basin (SLO Basin) is a high priority basin. The SLO Basin, which underlays the City and unincorporated`r; areas outside of the City, was designated�f as a high priority basin by the State of , -ro California due to the documented Figure 1 - Overview of the SLO Basin lowering of groundwater levels in the eastern portion of the basin, near Edna Valley, and the population overlying the basin in the western (City of San Luis Obispo) portion of the basin. SGMA legislation defines "Sustainable Groundwater Management" as the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon (2022-2042) without causing undesirable results. The goal of the SGMA legislation is to ensure groundwater basins are managed sustainably and that groundwater extraction within a basin is not exceeded by pumping/withdraw over an extended period of time, causing undesirable results to the basin and significant and unreasonable impacts to its users. 2. City and County GSA Formation and GSP Timeline SGMA grants local agencies the authority to sustainably manage groundwater supplies and allows for State intervention, when necessary, to protect groundwater resources. SGMA requires the creation of Groundwater Sustainability Agencies (GSAs) to develop and implement local plans, allowing 20 years to achieve sustainability. SGMA required the formation of GSAs by June 2017. The City of San Luis Obispo (City) and the County Page 12 of 1183 Item 3a of San Luis Obispo (County) completed the GSA formation process and entered into an agreement to produce one Groundwater Sustainability Plan (GSP) which would cover the entirety of the SLO Basin (Attachment E). Page 13 of 1183 Item 3a This GSP must be adopted by both GSAs by January 31, 2022. Once adopted by both the City and County GSAs, and approved by California Department of Water Resources (DWR), implementation of the Groundwater Sustainability Plan will occur, and the GSAs will have until 2042 to achieve sustainability of the SLO Basin. Per SGMA, sustainability is defined as the management and use of groundwater that can be maintained without causing an Undesirable Result (defined below). A Groundwater Sustainability Commission (GSC), comprised of significant users of groundwater in the SLO Basin, was formed as an advisory body to the City and County GSAs (Attachment E). Upon the recommendation of this GSC, this report is intended to inform the City GSA and the public of the progress made to date on the development of the Groundwater Sustainability Plan. 11112015: 3131116: SGMA Boundary enacted n1odifical on T T 61301201 7: 113112022 Bt-_�bl s- Adopt GSA GLIS, P ■ T Goal: Achieve sustainability Figure 2 - SGMA Timeline 3. Sustainable Yield: Two Values in SLO Basin by Subarea, One in Surplus (San Luis Valley Subarea), the Other in Deficit (Edna Valley Subarea) "Sustainable Yield," according to SGMA, means the maximum volume of water, calculated over a period of time that is representative of long-term conditions in the basin, that can be withdrawn each year from a groundwater supply without causing undesirable results (defined below and within Attachment A). For the SLO Basin the Sustainable Yield is estimated to be 5,800 acre-feet per year (AFY), as shown in Table 1. The Subarea of the basin underlying the City (San Luis Valley Subarea) is estimated to have a 700 AFY year surplus of groundwater. However, the Edna Valley Subarea of the basin experiences an estimated 1,100 AFY deficit due to excessive groundwater use. The SLO Basin as whole is estimated to be overdrafted by 400 AFY on average. As a result of a large geographic bedrock divide between the two portions of the basin, actions taken on one side of the basin have minimal impact on water levels on the other side of the basin. Overdraft and surplus volumes for the SLO Basin and the two subareas can be seen in Table 2 below. Page 14 of 1183 Item 3a *Surplus water available Sustainability Indicators are the effects caused by groundwater conditions occurring throughout the basin that, when significant and unreasonable, become Undesirable Results. As defined by SGMA, Undesirable Results are one or more of the following effects: 1. Chronic lowering of groundwater levels 2. Significant and unreasonable reductions in groundwater storage 3. Significant and unreasonable seawater intrusion (does not apply to the SLO Basin) 4. Significant and unreasonable degradation of water quality 5. Significant and unreasonable land subsidence; and 6. Surface water depletions that have significant and unreasonable adverse impacts on beneficial uses Previously Reviewed: Draft Chapters 1-6 The research and writing of the GSP is a complex multi -year process. Council previously reviewed and provided comment on the first six draft chapters of the GSP on December 8, 2020. While largely administrative in nature, these chapters established an understanding of the hydrology and geology of the groundwater basin, the characteristics of water use within the basin, and the nature and extent of the imbalance of water flowing into the basin versus water being pumped from the basin within the Edna Valley area. Chapters 1-6 are provided within Attachment B of this staff report as follows: Chapter 1: Introduction to the SLO Basin GSP Chapter 2. Agency Formation (§ 354.6) Chapter 3: Description of Plan Area Chapter 4. Basin Setting Chapter 5: Groundwater Conditions Chapter 6. Water Budget (§ 354.18) The staff report from the December 8, 2020 Council meeting, which summarizes each of these chapters, can be found in Attachment C. GSP Draft Chapters 7-10 and Groundwater Dependent Ecosystem Technical Memorandum Since the December 8, 2020 Study Session, the final four chapters of the GSP and an associated technical memorandum have been drafted and released for public comment and Council input at this Study Session. A complete, "Administrative Draft" of the GSP containing all ten chapters is scheduled to be released for public review on October 18, 2021. The draft chapters attached to this report are subject to change as comments are Page 15 of 1183 Item 3a received from stakeholders, the City and County GSAs, and GSC members. Chapters 7- 10 are provided in full within Attachment B and a technical memorandum regarding protection of Groundwater Dependent Ecosystems (GDEs) is provided within Attachment D. Each of these attachments were recommended by the GSC to be received and filed by the City and County GSAs. The attached chapters and technical memorandum are outlined Page 16 of 1183 Item 3a as follows: Chapter 7: Monitoring Network Chapter 8: Sustainable Management Criteria Chapter 9: Projects and Management Actions Chapter 10: Implementation Plan Technical Memorandum on Groundwater Dependent Ecosystems (GDEs) Chapter 7: Monitoring Network A groundwater basin that is subject to SGMA is required to establish a monitoring network in which various types of data are collected to ensure the basin is operated in a sustainable manner and to monitor progress toward meeting SGMA compliance and basin sustainability goals. As a part of the larger monitoring network, an individual network is established for groundwater levels, another for groundwater quality, and a final network for surface water flow. These networks help monitor data for each of the six Sustainability Indicators. The three monitoring networks must be capable of capturing data on a sufficient temporal and spatial distribution to demonstrate short-term, seasonal, and long-term trends in groundwater and related surface water conditions, and to yield representative information about these conditions for GSP implementation, tracking, reporting, and groundwater model calibration. Staff Recommendation: After in-depth review of Chapter 7, staff finds that it is consistent with City policies and sufficient to meet the legal requirements of SGMA. Chapter 8: Sustainable Management Criteria A significant effort in the creation of a Groundwater Sustainability Plan involves the development of a measurement system to determine the current health of the basin and measurable action points where intervention may be needed if goals are not being met. SGMA regulations group this system together under the heading of "Sustainable Management Criteria". These criteria are defined in detail in Chapter 8 found in Attachment B and include: • The Basin's Sustainability Goal • Undesirable Results • Minimum Thresholds, and • Measurable Objectives Page 17 of 1183 Item 3a For each of the six Sustainability Indicators, Undesirable Results are defined, and Minimum Thresholds and Measurable Objectives are established. These metrics are an important part of the GSP as they identify metrics to determine if the Groundwater Sustainability Plan is meeting its intended goal of sustainability and identify the starting point at which corrective actions must begin if goals are not met. 1. Discussion of Chapter 8's SLO Basin's Sustainability Goal The sustainability goal for the SLO Basin is a statement that describes the important factors to be considered during the SGMA planning horizon (2022-2042). The sustainability goal was developed over a series of public meetings and public workshops with input from the City, County, and affected stakeholders. The June 10, 2020 Stakeholder Workshop, Groundwater Management Vision, was dedicated to obtaining information to be used to develop a sustainability goal for the SLO Basin. In the workshop, stakeholders participated in an interactive visioning exercise where they helped populate a virtual white board to answer the question, "What is our shared vision of what a `sustainable SLO Basin' means?" Guiding principles of this goal are: • Available groundwater supply supports diverse needs reliably and equitably • Stored groundwater equitably supports supply resilience and evolving needs • Groundwater levels support the sustained health of groundwater dependent ecosystems • Cost of maintaining sustainable groundwater levels is equitably distributed • Groundwater quality is maintained to a safe standard to meet diverse basin needs After further coordination with the GSAs, GSC members, and other stakeholders, a sustainability goal was drafted. The sustainability goal for the Basin is to, "manage the Basin to ensure beneficial uses and basin users have access to a safe and reliable groundwater supply that meets current and future demand without causing undesirable results". After in-depth review of Chapter 8, staff finds that it is consistent with City policies and sufficient to meet the legal requirements of SGMA. Chapter 9: Projects and Management Actions Chapter 9 describes the Projects and Management Actions that have been identified as providing feasible methods to achieve sustainable management goals in the SLO Basin. The projects and management actions were developed over a series of working sessions with GSA staff and in six public GSC meetings between December 9, 2020 and June 21, 2021. Page 18 of 1183 Item 3a Projects can generally be described as infrastructure -related improvements and water purchase agreements designed to increase the amount of water available within the Edna Valley subarea. Due to water levels being stable within the City's subarea, projects are not recommended within the City limits. Projects identified for the Edna Valley subarea could include imported water being directly utilized by agricultural operations and/or local residents for domestic and irrigation uses, or imported water being used to recharge the Edna Valley subarea to benefit all of the users of the subarea. Management Actions can generally be described as actions needed in order to directly reduce the amount of groundwater pumping within the basin. It is important to note that the projects and management actions listed in the draft GSA have been included based on their feasibility from an engineering/infrastructure perspective solely and in some instances are inconsistent with City polices and/or may have impacts to the City's overall water resources. Identification of a project within the GSP does not obligate the GSAs or project participants to implement the project and some of the projects identified are inconsistent with existing City policies and are not supported by staff as actionable given the policy conflict. Figure 3 — Projects and Management Actions Strategies (GSP Table 9-3) provides a summary of the projects and management actions considered in the SLO Basin GSP. The table shows the status, timing for implementation (years), capital costs ($), annual Operations and Maintenance (O&M) ($/Year), quantity of water delivered in acre-feet per year (AFY), and the unit cost ($/AFY) for each project and management action. Project costs outlined within the table do not include the cost of the water being purchased as this would have to be negotiated with the party who holds rights to the water. This table also does not assess the policy inconsistencies and likelihood that projects could or should occur given that conflict. It should be noted that the absence of the negotiated sales price of water and the legal and/or policy constraints make certain projects potentially unactionable and others infeasible. City of San Luis Obispo Water Sales Projects The City is not proposed as a recipient of any projects identified within the GSP due to the surplus of groundwater currently available within the San Luis Valley Subarea. However, two projects are identified within the plan that would involve the sale of potable and/or recycled water from the City to parties within the Edna Valley subarea. One project considers the sale of 500-800 AFY of recycled water to the Edna Valley Growers for agricultural irrigation. Another considers the sale of 200 AFY of potable water from the City to Golden State Water Company's Edna Valley service area. City policy allows for the sale of recycled water and raw water outside of City limits under specific conditions and does not permit the sale of potable water outside of City limits. Thus, for the potable water sales project to be approved, the Council would need to significantly modify its existing General Plan policies related to outside -City water sales. Page 19 of 1183 Item 3a SLO Basin Groundwater Sastonability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO Table 9-3 Projects and Management Actions Strategies Projects and Imp�ementatian Annual Annual Total Quantity Unit Cast Management Status Timing Capital Cast capital Annual of Water Actions Payment Payment �AFJ Feasibility study_ 0to SWP toAg Not begun 1years $ 890,000 $ 58,000 $ 5,O00 $ 63,00O 1,OCO S 60 Irrigation yet Design/Construction- 1 1 to 5 years Evaluated as City of SLO part of the Feasibility study_ 0 to Recycled Water City of SLO 1 years $ 1,004,000 $ 65,000 $ 88,000 $153,000 600 $ 260 Recycled Design/Construction: to Ag Irrigation Water Study 1 to 3 years (2017) Feasibility study: 0 SWP Recharge Not begun to 1 years $ 3,624,000 $ 236,000 $ 101,000 $ 337,000 500 $ 670 yet Design/Construction: 1 to 5 years Feasibility study_ 0 SWP to GSWC Not begun to 1 years $ 2,6851000 $ 175,000 $ 17,000 $ 192,000 200 $ 960 yet Design/Construction- 1 to 5 years City of SLO Feasibility study: 0 Potable Waterto Not begun to 1 years $ 1,739,000 $ 127,000 $ 14,000 $ 127,0O0 200 $ 640 yet Design/Construction: GSWC 1 to 3 years Varian Ranch Feasibility study: 0 MWCAG Not begun to 1 years $ 2,701,000 $ 176,000 $ 34,000 $ 210,000 50 $ 4,200 Subbasin Wells yet DesignfConstruction: 1 to 3 years Feasibility study: 0 SWP to Mutual Not begun to 1 years $ 835,000 $ 54,000 $ 5 O00 $ 59,000 50 $ 1,180 Water Companies yet DesignfConstruction- 1 to 5 years Mitigated Feasibilitystudy: 0 Price Canyon Discharge Negative Dec to 1 years $ 4,9O9,000 $ 319,000 $ 56,000 $ 375,000 5W $ 750 Relocation Completed in Design/Construction: 2015 1 to 3 years East Corral de Feasibility study_ 0 Piedra Not ot begun to 1 years yet Design/Construction- $ 3,169,000 $ 206,000 $ 101,000 $ 307,000 50 $ 6,140 Capture and Recharge 1 to 3 years Groundwater Not begun Extraction y et 1 year Metering Plan Demand Not begun Managemerrt y et As needed Strategies 1. Does not in€I ude the cost of the water_ 2. quantity of water at the discharge point_ Figure 3- Projects and Management Actions Strategies Page 20 of 1183 Item 3a City of SLO Recycled Water Sales to Edna Valley Growers The City's Water Resource Recovery Facility (WRRF) treats municipal wastewater from the City, Cal Poly, and the San Luis Obispo County Airport and in return produces recycled water. Once produced, recycled water is distributed within the City for landscape irrigation and construction uses, and dechlorinated and discharged to San Luis Obispo Creek for environmental benefit. The WRRF is required to maintain a minimum daily average year-round discharge of 2.5 cubic feet per second (cfs) of treated effluent to San Luis Obispo Creek, which equals approximately 1.6 million gallons per day (MGD) or 1,800 AFY, for protection of downstream biological resources as required by the National Oceanic Atmospheric Association, National Marine Fisheries Service. With current in -City recycled water demands increasing and influent into the WRRF decreasing due to high levels of water conservation, it may be feasible for the City to provide the Edna Valley growers with 500-800 acre-feet of recycled water annually with quantities decreasing as new in -City users come online. In -City groundwater basin augmentation efforts, new regulations, drought, and additional in -City recycled water irrigation customers could further reduce the quantity of recycled water available to outside users by several hundred acre-feet in the foreseeable future. The Council budgeted $50,0000 to develop a comprehensive understanding of the future availability of recycled water, the cost to deliver recycled water to outside City users, pricing and equity parameters with existing City ratepayers given past investments or sunk costs, and water rights implications. This funding will ensure that the City's water rights are protected, volumes of recycled water available for sale are understood and maximized, and that sales pricing and price structures are designed to ensure equity to the City's water rate payers. Lastly, it will help inform the City about ways to maximize its recycled water supplies when needed to meet needs within the City. The Council budgeted $50,0000 to develop a comprehensive understanding of the future availability of recycled water, the cost to deliver recycled water to outside City users pricing and equity parameters with existing City ratepayers given past investments or sunk costs, and water rights implications, $. This funding will ensure that the City's water rights are protected, volumes of recycled water available for sale are understood and maximized, and that sales pricing and price structures are designed to ensure equity to the City's water rate payers. Lastly, it will help inform the City about ways to maximize City of SLO supplies when needed to meet needs within the City. Existing General Plan policy allows for the sale of recycled water outside of City limits when certain findings are made, as follows: Provision of non -potable or recycled water outside of City limits may only be considered in compliance with Water and Wastewater Element Policy A 7.3.4 and the following findings. - A. Non-potable/recycled water is necessary to support continued agricultural operations. Page 21 of 1183 Item 3a B. Provision of non-potable/recycled water will not be used to increase development potential of property being served. C. Non-potable/recycled water will not be further treated to make it potable. D. Prior to provision of non-potable/recycled water, the property to be served will record a conservation, open space, Williamson Act, or other easement instrument to maintain the area being served in agriculture and open space while non-potable/recycled water is being provided. Page 22 of 1183 Item 3a E. Provision of non -potable and recycled water will not impair the City's ability to maintain an adequate water supply that meets projected water demand at buildout under the General Plan including the required reliability reserve. Water and Wastewater Management Element, Program A 7.3.4 allows for the sale of recycled water outside of City limits as follows: Consider the potential to deliver available non -potable or recycled water supplies to customers outside the city limits, including analysis of policy issues, technical concerns, and cost recovery, provided it is found to be consistent with the General Plan. Staff Recommendation: Staff is supportive of this project being included in the GSP based on existing policy that allows for the sale of recycled water outside of City limits. However, staff recommends completion of the recycled water maximization study prior to entering into negotiations with the Edna Valley Growers to ensure protection of the City's water rights and to provide the City's rate payers with maximum benefit from recycled water sales. City of SLO Potable Water Sale to Golden State Water Company (GSWC) This project involves the concept of GSWC purchasing treated drinking water from the City on an interruptible basis to augment their current supply from wells within their service area. The City has longstanding policy that does not allow for potable water to be sold outside of City limits. General Plan Chapter 1.13.1 Water and Sewer Service states: The City shall not provide nor permit delivery of City potable water or sewer services to the following areas. However, the City will serve those parties having valid previous connections or contracts with the City. A. Outside the City limits,- B. Outside the urban reserve line; Analysis of this project was included in the draft GSP so that a basic analysis of cost and technical feasibility is documented in the event that there was a significant departure from existing City policy regarding the sale of potable water supplies outside of its service area. Staff Recommendation: Staff does not support this project due to existing policy that prohibits the sale of potable water outside of City limits. Staff recommends removal of this project from the GSP as there is no policy basis for its inclusion. Page 23 of 1183 Item 3a Non -City Water Supply Projects A variety of water supply projects exist within the region that allow for both potable and non -potable water to be imported to the Edna Valley subarea. Below is a brief summary of these projects and staff's analysis related to the benefit of each of the projects. A full list of projects and detailed project descriptions can be found within Chapter 9.4 of the GSP. This report provides a highlight of many of the major projects contained within the GSP but does not detail all of the identified projects. 1. Highest Ranked GSP Project: Obtain State Water Project (SWP) for Agricultural Irrigation in the Edna Valley Subarea The Coastal Branch of the SWP conveys water from Northern California to San Luis Obispo County. As part of a ranking/scoring exercise that examined volumes of water available, water supply reliability, costs, implementation timelines, and various other factors, the delivery of SWP water to the Edna Valley subarea for use for agricultural irrigation was the highest ranked project. This water supply project is the only project identified within the GSP that can provide the total volume of water needed to eliminate overdrafted conditions within the Edna Valley subarea. It is anticipated that the Edna Valley growers could purchase over 1,000 acre- feet of water annually and directly apply this water to crops in order to reduce groundwater pumping by an equivalent volume. Without the use of SWP for agricultural use, the Edna Valley area would need to implement a combination of several other projects and/or management actions, such as pumping reductions, in order to achieve sustainability. Staff Recommendation: Staff is supportive of this project being included in the GSP as it is the only project identified within the GSP that can by itself provide an adequate volume of water to return the Edna Valley subarea to sustainability. This project also provides opportunities to share project implementation costs with others within the Edna Valley subarea who could also benefit from the use of SWP water. The purchase of SWP water is one of the only projects identified that does not have limitations on how long the water may be available, thus providing a permanent solution to overdrafted conditions within the Edna Valley subarea. 2. State Water Project to Golden State Water Company (GSWC) Golden State Water Company currently provides water to a small service area of County administered land in the central part of the SLO Basin, near the bedrock divide that separates the Edna Valley subarea and San Luis Valley subarea. GSWC obtains its water supply from groundwater wells within its service area. The recent drought resulted in significant constraints on GSWC's groundwater supplies. Because their service area is relatively small, their ability to site new wells to expand their source locations is limited. For this reason, the conceptual project of obtaining SWP water to augment GSWC's current supplies was evaluated within the GSP. Page 24 of 1183 Item 3a This project assumes a SWP delivery of 200 AFY to GSWC, representing about 50% of GSWC's long-term water demand. This project would result in a 200 AFY reduction in groundwater pumping within the Edna valley subarea and is the one of only two water supply projects identified that would provide GSWC with a secondary source of potable water. All other projects either benefit GSWC indirectly through reducing demand on the groundwater basin or supplementing the basin with water that could later be extracted through groundwater pumping. While not required by SGMA, this project provides water supply diversification and resiliency to GSWC's customers. Staff Recommendation: Staff is supportive of inclusion of this project within the GSP. Aside from the sale of the City's potable water resources, SWP water is the only project identified within the GSP that can provide an alternative supply of potable water for domestic use. 3. State Water Project to the Mutual Water Companies The Varian Ranch Mutual Water Company and Edna Ranch Mutual Water Company, located in the southeastern extent of the Edna Valley subarea, currently provide water to their service areas from wells within the SLO Basin. The recent drought resulted in significant constraints on their water supplies and groundwater levels within this area are steadily declining. Like the above section involving SWP delivery to GSWC, delivery of SWP water to the two mutual water companies would allow for reduced groundwater pumping (50 AFY), the introduction of an alternative source of potable water for supply resiliency and diversification, and a water supply that is available through the entire SGMA planning horizon (2022-2041). Staff Recommendation: Staff is supportive of this project as it, would provide a secondary source of potable water to the mutual water companies' service areas, resulting in greater regional resiliency. This project could benefit from a cost share with the Edna Vallely Growers and GSWC to alleviate some of the infrastructure - related costs of connection to the SWP. 4. State Water Project Recharge Basin To enhance groundwater recharge in the Edna Valley, a recharge basin could be constructed to percolate imported SWP water into the basin. A groundwater recharge basin is a bermed basin structure designed for the purpose of efficiently allowing water collected in the basin to infiltrate through the ground surface, and ultimately recharge the underlying aquifer. The concept of this project is to construct a recharge basin in the Edna Valley and supply it with water obtained from the SWP to recharge the aquifer. This project could recharge 500 acre-feet or more State Water Project water into the basin each year, representing roughly half of the estimated need of the Edna Valley area. Page 25 of 1183 Item 3a The SWP experiences inconsistent availability year-to-year, with an average of 60% delivery since its inception. The storage of SWP within the basin allows for storing water within the basin during periods when substantial volumes of water are available from the SWP and relying upon stored water during years when SWP volumes may be reduced due to drought. This storage project should be used in conjunction with the SWP projects mentioned above to make best use of SWP when it is available in the highest volumes. Staff Recommendation: Staff is supportive of this project as it would allow for the storage of SWP within the groundwater basin, helping to alleviate inconsistent delivery of SWP during abnormally dry periods and allowing recharged water to be stored without loss to evaporation from above ground storage. 5. Price Canyon Discharge Relocation (Sentinel Peak) Sentinel Peak Resources LLC is an energy company that operates a well field that extracts petroleum hydrocarbons from an area approximately 1-2 miles southwest of Edna Valley in Price Canyon. Sentinel Peak owns and operates a process water reclamation facility that has a permit to discharge into Pismo Creek about 1 mile southwest of Highway 227 near Price Canyon Road. The discharge permit is primarily provided for increased flow in Pismo Creek and wildlife propagation with a secondary benefit to agriculture. The proposed project would change the current point of discharge by about 3.5 miles by moving it to the upper portion of West Corral de Piedras Creek in the Edna Valley. The new discharge point would be approximately 1 mile east of Orcutt Road. The project would provide increased benefit to fisheries from increased streamflow, and also benefit Edna Valley agriculture by increasing streamflow percolation to the underlying aquifer. For the purpose of the GSP, it was assumed that 500 AFY of water would be available to deliver to the new discharge location, resulting in approximately 350 acre-feet of recharge to the SLO Basin. Due to the migration towards clean energy alternatives, some uncertainly exists around the long-term availability of water from Sentinel Peak. Staff Recommendation: Staff is supportive of this project, with the understanding that water imported as part of this project is dependent on the continued operation of the Sentinel Peak facility. Management Actions Management actions are taken by basin users to mitigate or avoid Undesirable Results. The management actions in the GSP include the expansion of the monitoring network (wells and stream gauges), development and implementation of a groundwater extraction metering and reporting plan, and the development of a demand management plan that includes pumping reductions. While direct pumping reductions would not be anticipated within the City due to stable water levels within the area of the basin underlaying the City, management actions such as expansion of the monitoring network and implementation of a groundwater extraction and reporting plan could involve the City. Page 26 of 1183 Item 3a Adaptive Management The GSP implementation process requires annual reporting and updates to the GSP at minimum every five years. These reporting requirements provide opportunities for the GSAs to evaluate progress towards meeting its sustainability goals and avoiding undesirable results. Adaptive management triggers are thresholds that, if reached, initiate the process for considering implementation of adaptive management actions or projects. For SLO Basin, the trigger for adaptive management is the following: • If analytical or modeled projections anticipate that future conditions will exceed the undesirable result thresholds, then the preparation for implementation of additional projects and management actions would begin. • If actual conditions exceed the undesirable result thresholds, then additional projects and management actions will be implemented. Chapter 10: Implementation Plan Chapter 10 is intended to serve as a conceptual roadmap and schedule for the GSAs to start implementing the GSP during the first five years following GSP adoption. The implementation plan provided in this chapter is based on current understanding of SLO Basin conditions and includes consideration of the projects and management actions included in Chapter 9, as well as other actions that are needed to successfully implement the GSP, including: 1. GSP implementation, administration, and management 2. Fee Studies and Funding 3. Reporting, including annual reports and five-year evaluations and updates 1. Future Governance Structure The GSAs and the GSC will continue to operate under the existing City/County Memorandum of Agreement (MOA) (Attachment E), including the existing governance structure, until actions are taken amending/revising the existing MOA or developing new agreements. The existing MOA will automatically terminate upon DWR's approval of the SLO Basin GSP (generally 18-24 months after GSP adoption). During the GSP review period, the GSAs will need to update the governance structure to better serve the implementation of the GSP. The existing governance structure consists of the two GSAs and an advisory body, known as the Groundwater Sustainability Commission with representatives from the Edna Valley Growers, Golden State Water Company, Edna and Varian Ranch Mutual Water Companies, City of San Luis Obispo, and County of San Luis Obispo. The structure of having an advisory body to the two GSAs has been effective throughout the creation of the GSP. Staff Recommendation: Staff recommends continuation with the existing governance structure during the GSP implementation phase. Page 27 of 1183 Item 3a Staff Recommendation: Staff recommends continuation with the existing governance structure which designates the GSC as an advisory body to the GSAs during the GSP implementation phase. 2. Implementation Schedule and Costs The GSP implementation schedule shown in Figure 10-1 of Chapter 10 of the GSP illustrates activities necessary for ongoing GSP monitoring and updates, as well as tentative schedules for the development of projects and management actions. GSP-related costs can be broken into two categories, one category for project -related costs, and another for implementation related costs. As defined in the GSP, project costs are not yet fully developed and are anticipated to be borne in full by project beneficiaries. Since the City is not a project beneficiary, staff do not anticipate any project -related costs for the City. Implementation -related costs are those required to implement the GSP and include annual and five-year reporting costs, monitoring network expansion costs, and administrative and finance costs. These costs are anticipated to be borne by the City in proportions directly related to the benefit received or cost incurred by the City. A fee study is scheduled to be conducted in 2022 in order to establish funding mechanisms and cost distribution associated with GSP funding. The implementation portion of the GSP is estimated to cost approximately $965,000 per year for the first five years of implementation and should be split proportionately across the SLO Basin. Annual implementation costs in years 6 through 20 should be reduced and will be developed during future updates of the GSP. Staff Recommendation: Staff recommends that the City only pay its proportional share of GPS implementation related costs and the City not contribute financially to projects that do not provide direct benefit to its water rate payers. Draft Technical Memorandum on Groundwater Dependent Ecosystem (GDEs) In addition to recommending that the City GSA receive and file Chapters 7-10 of the GSP, the GSC also recommended that the GSAs receive and file a Draft Technical Memorandum on Groundwater Dependent Ecosystems (Attachment D). This technical memorandum will be included with the final GSP as an appendix and provides supporting documentation for several GSP chapters. GDEs are defined in SGMA as "ecological communities of species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface." The purpose of the GDE Technical Memorandum is to: 1. Summarize known information about surface water hydrology relevant to GDEs in the SLO Basin 2. Identify GDEs overlying and dependent upon the SLO Basin 3. Identify sustainable GDE indicators for the SLO Valley Groundwater Basin 4. Propose a hydrologic monitoring network to track these indicators over time Page 28 of 1183 Item 3a The full technical memorandum regarding protection of Groundwater Dependent Ecosystems (GDEs) is provided within Attachment D. Next Steps To -date all ten chapters of the GSP have been drafted and released individually for public comment. Staff is compiling an Administrative Draft of the GSP which will be released for public comment from August 18, 2021 through September 18, 2021. During this public comment period, staff will return to the City Council on September 7, 2021 to report on the GSP Administrative Draft and an outline of any significant changes made to the GSP draft chapters. After the GSP Administrative Draft public comment period closes, staff will review any received comments and implement changes as necessary. On October 6, 2021 the Groundwater Sustainability Commission will vote on recommending GSP adoption to the City and County GSAs. Following final adoption of the GSP by the GSAs on December 7, 2021, the GSP will be submitted to the Department of Water Resources. 5 Steps to Sustainable Groundwater in the SLO Basin 1rnV, 2020 j 2021 JAN, 2 02 2 To -date all ten chapters of the GSP have been drafted and released individually for public comment. Staff is compiling an Administrative Draft of the GSP which will be released for public comment from August 18, 2021 through September 18, 2021. Page 29 of 1183 Item 3a Figure 4 — GSP Development Steps FOCUS AREAS FOR COUNCIL DISCUSSION AT THIS STUDY SESSION Question #1. Does the City Council wish to continue with the existing governance structure, which includes a Groundwater Sustainability Commission that acts as an advisory body to the City and County GSAs, during the GSP implementation period (2022-2042)? Question #2. Does the City Council support staff's recommendation that GSP implementation costs, including the costs to construct projects, should be borne by those benefitting from the project(s) or action(s) and that the City should only be responsible for its proportional share of GSP implementation costs? Question #3. Does the City Council support the inclusion of a project to sell City Recycled Water to the Edna Valley Growers within the GSP, in alignment with existing General Plan policies? Question #4. Does the City Council support staff's request for the removal of the Potable Water Sales to Golden State Water Company project from the GSP due to direct conflict with existing General Plan policies regarding outside -city potable water sales? Page 30 of 1183 Item 3a Question #5. Does the City Council support staff's recommendation to include all State Water -related Projects to the Enda Valley subarea and the Sentinel Peak Discharge Relocation Project within the GSP? Question #6 What other comments does the Council want to provide on the GSP? CONCURRENCE The Community Development Department concurs with this report. 4►1y/l:to]kiIJi141!kr_10NATAIATA This study session does not constitute a "Project" under State CEQA Guidelines Sec. 15378. No discretionary action will be taken by the City Council until the Groundwater Sustainability Plan is brought forward for consideration and adoption, tentatively scheduled for December, 2021. In addition, preparation and adoption of a Groundwater Sustainability Plan is statutorily exempt from CEQA, pursuant to Water Code Division 6, Part 2.74, Chapter 6, Section 10728.6. 1 Adoption of the Groundwater Sustainability Plan would not authorize implementation of specific projects, and any project that would implement actions taken pursuant to an adopted Groundwater Sustainability Plan will be subject to CEQA review at the time the project is considered for approval and implementation. FISCAL IMPACT As proposed within the GSP, the City is not proposed to bear financial responsibility for the projects and management actions needed within the Edna Valley subarea. Costs related to the implementation of the GSP are proposed to be proportionally shared between the City and other groundwater users within the entirety of the SLO Basin, and are estimated to be $965,000/year for 2022-2026. Costs and cost distribution are projected to be further defined in the fee study scheduled for the first quarter of 2022. Budgeted: NA Budget Year: NA Funding Identified: NA California Water Code Section 10728.6 states: "Division 13 (commencing with Section 21000) of the Public Resources Code [CEQA] does not apply to the preparation and adoption of plans pursuant to this chapter. Nothing in this part shall be interpreted as exempting from Division 13 (commencing with Section 21000) of the Public Resources Code [CEQA] a project that would implement actions taken pursuant to a plan adopted pursuant to this chapter." Page 31 of 1183 Item 3a ALTERNATIVES Request staff return to the City Council, acting as the GSA, with additional information regarding GSP development. ATTACHMENTS A — Terms and Definitions B — Draft GSP Chapters 1-10 C — December 8, 2020 SGMA Council Agenda Report D — Draft Technical Memorandum on Groundwater Dependent Ecosystems (GDEs) E Memorandum of Agreement Page 32 of 1183 Terms and Definitions Groundwater Dependent Ecosystems (GDEs) Ecological communities of species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface. Groundwater Sustainability Agencies (GSAs) Local public agencies tasked with developing and implementing Groundwater Sustainability Plans under SGMA. Groundwater Sustainability Commission (GSC) An advisory board to the City and County GSAs, comprised of significant potential users of groundwater in the SLO Basin. Groundwater Sustainability Plan (GSP) A 20-year plan to ensure that groundwater is managed sustainably within a groundwater basin. Interim Milestones (IMs) Target values representing measurable conditions, set in increments of five years, designed to help the basin achieve sustainability by 2042. Measurable Objectives (MOs) Specific, quantifiable goals for the maintenance or improvement of specified groundwater conditions to achieve the sustainability goal for the basin. Measurable Objectives are goals that the GSP is designed to achieve. Minimum Thresholds (MTs) The quantitative values that define what is deemed significant and unreasonable at each Representative Monitoring Site. Monitoring Network A collection of monitoring points that promote the collection of data of sufficient quality, frequency, and distribution to characterize groundwater and related surface water conditions in the basin and evaluate changing conditions that occur through implementation of the Groundwater Sustainability Plan. Representative Monitoring Sites (RMSs) Representative Monitoring Sites are individual locations within a Monitoring Network at which sustainability indicators are monitored, and for which quantitative values for Minimum Thresholds, Measurable Objectives, and Interim Milestones are defined. Sustainability Goal A comprehensive statement that describes the goals for sustainability within the basin and important factors to be considered during the SGMA planning horizon (2022-2042). Page 33 of 1183 Sustainable Groundwater Management The management and use of groundwater in a manner that can be maintained during the planning and implementation horizon (2022-2042) without causing Undesirable Results. Sustainability Indicators The effects caused by groundwater conditions occurring throughout the basin that, when significant and unreasonable, cause Undesirable Results such as chronic lowering of groundwater levels, significant and unreasonable reductions in groundwater storage, significant and unreasonable seawater intrusion, significant and unreasonable degradation of water quality, significant and unreasonable land subsidence, and surface water depletions that have significant and unreasonable adverse impacts on beneficial uses. Sustainable Yield The maximum volume of water, calculated over a period of time that is representative of long-term conditions in the basin, that can be withdrawn each year from a groundwater supply without causing undesirable results. Undesirable Results 1. Chronic lowering of groundwater levels 2. Significant and unreasonable reductions in groundwater storage 3. Significant and unreasonable seawater intrusion (does not apply to the SLO Basin) 4. Significant and unreasonable degradation of water quality 5. Significant and unreasonable land subsidence; and 6. Surface water depletions that have significant and unreasonable adverse impacts on beneficial uses. Page 34 of 1183 Draft Groundwater Sustainability Plan forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agency Prepared by SC WATER SYSTEMS CONSULTING, INC. L GSA GE1 consui�ants Stillwater ScienceswaWsomtionOnL 8/30/2019 Page 35 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO TABLE OF CONTENTS Tableof Contents........................................................................................................................................... i Listof Figures............................................................................................................................................... iii Tables........................................................................................................................................................... iv Appendices.................................................................................................................................................... v Listof Terms Used........................................................................................................................................ vi ExecutiveSummary.......................................................................................................................................1 1 Introduction to the SLO Basin GSP.......................................................................................................2 1.1 Purpose of the Groundwater Sustainability Plan..........................................................................2 1.2 Description of SLO Basin............................................................................................................... 2 1.3 Basin Prioritization........................................................................................................................ 3 2 Agency Information (§ 354.6)..............................................................................................................5 2.1 Agencies Names and Mailing Addresses.......................................................................................5 2.2 Agencies Organization and Management Structures...................................................................7 2.2.1 County of San Luis Obispo.....................................................................................................8 2.2.2 City of San Luis Obispo..........................................................................................................8 2.2.3 Other Participating Parties in the MOA................................................................................8 2.2.3.1 Edna Valley Growers Mutual Water Company.............................................................8 2.2.3.2 Varian Ranch Mutual Water Company.........................................................................8 2.2.3.3 Edna Ranch Mutual Water Company............................................................................8 2.2.3.4 Golden State Water Company......................................................................................8 2.3 Authority of Agencies....................................................................................................................8 2.3.1 Groundwater Sustainability Agencies...................................................................................8 2.3.1.1 County of San Luis Obispo.............................................................................................8 2.3.1.2 City of San Luis Obispo..................................................................................................9 2.3.2 Memorandum of Agreement................................................................................................9 2.3.3 Coordination Agreements.....................................................................................................9 2.4 Contact information for Plan Manager.........................................................................................9 3 References..........................................................................................................................................11 4 Appendices.........................................................................................................................................11 Appendix A - City of San Luis Obispo Resolution to form GSA...............................................................11 Appendix B - County of San Luis Obispo Resolution to form GSA..........................................................15 Appendix C - Memorandum of Agreement — Preparation of GSP.......................................................... 20 Page 36 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO Page 37 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Figures LIST OF FIGURES Figure 1-1: San Luis Obispo Valley Basin and Surrounding Basins................................................................4 Figure 2-1: San Luis Obispo Valley Basin GSAs and Participating Parties.....................................................6 Figure 2-2: Groundwater Sustainability Commission (GSC).........................................................................7 Page 38 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO TABLES No table of figures entries found. Tables iv Page 39 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES A. City of San Luis Obispo Resolution to form GSA B. County of San Luis Obispo Resolution to form GSA C. Memorandum of Agreement— Preparation of GSP Appendices Page 40 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level MG Million Gallons vi Page 41 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant vii Page 42 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 43 of 1183 SLO Basin Groundwater Sustainability Plan Introduction to the SLO Basin GSP County of SLO and City of SLO 1 INTRODUCTION TO THE SLO BASIN GSP 1.1 PURPOSE OF THE GROUNDWATER SUSTAINABILITY PLAN The Sustainable Groundwater Management Act (SGMA), Section 10720, et. al., of the State Water Code, requires sustainable groundwater management in all high and medium priority basins. The San Luis Obispo Valley Groundwater Basin (SLO Basin) was designated as a high priority basin. To comply with and satisfy the requirements of SGMA, the following activities are mandated: • Forming one or more Groundwater Sustainability Agencies (GSAs) by June 30, 2017 to cover the entire SLO Basin. In May 2017, both the City of San Luis Obispo (City) and the County of San Luis Obispo (County) each formed GSAs within their jurisdictions, resulting in full coverage of the SLO Basin. • Developing a Groundwater Sustainability Plan (GSP) by the GSAs that covers the entire SLO Basin by January 31, 2022. • Implementing the GSP to achieve quantifiable objectives and sustainability within 20 years by 2042. • Annual reporting of groundwater conditions in the basin to the California Department of Water Resources (DWR). • Periodic (every five years) evaluation of the GSP implementation by the GSAs. This document fulfills the GSP development requirement for the SLO Basin. This GSP describes and assesses the groundwater condition of the SLO Basin, develops quantifiable management objectives that account for the interests of the SLO Basin's beneficial groundwater uses and users, and identifies a group of projects and management actions that will allow the SLO Basin to achieve and maintain sustainability in the future. 1.2 DESCRIPTION OF SLO BASIN This GSP covers the entire SLO Basin identified as Basin No. 3-009 in the DWR's Bulletin 118 (DWR, 2016). The SLO Basin lies in the southern portion of San Luis Obispo County. The SLO Basin is comprised of valleys of gentle flatlands and rolling hills ranging in elevation from approximately 100 to 500 feet above mean sea level, surrounded by larger mountain ranges. A terrain map displaying the SLO Basin boundaries is presented in Figure 1-1, which also displays the watershed areas of the San Luis Obispo Creek and Pismo Creek drainages, faults, and nearby groundwater basins symbolized by the SGMA 2019 Basin Prioritization Phase 1. Average annual precipitation ranges from approximately 18 inches throughout most of the SLO Basin to about 22 inches in relatively higher elevation areas near the City and Cal Poly. The SLO Basin is within the watershed areas of the San Luis Obispo Creek and Pismo Creek drainages, which are bounded on the northeast by the Santa Lucia Range and on the southwest by the formations of the San Luis Range and the Edna Fault. The SLO Basin is commonly referenced as being composed of two distinct valleys, with the San Luis Valley in the northwest and the Edna Valley in the southeast. The San Luis Valley lies within the San Luis Obispo Creek drainage and the Edna Valley lies within the Pismo Creek drainage. There is a bedrock high that underlies between the San Luis Valley and Edna Valley. The watershed divide and the bedrock high divide are not coincident. The sediments of the Edna Valley have significantly greater thickness than those of the San Luis Valley. Precipitation that falls west of the watershed divide ultimately flows to Davenport and San Luis Obispo Creeks, and precipitation that falls 2 Page 44 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Introduction to the SLO Basin GSP east of that divide flows to Corral de Piedras Creek or the other small tributaries, which ultimately flow to Pismo Creek south of the SLO Basin. San Luis Obispo and Pismo Creeks are the primary surface water features within the SLO Basin. Significant tributaries to the San Luis Obispo Creek within Basin include Prefumo Creek, Stenner Creek, and Davenport Creek. Significant tributaries to Pismo Creek include both East and West branches of the Corral de Piedras Creek. Urban areas within the SLO Basin include the City of San Luis Obispo, Cal Poly, Edna, and Verde. Highway 101 is the most significant north -south highway in the Basin. 1.3 BASIN PRIORITIZATION The DWR prioritized California's groundwater basins through the California Statewide Groundwater Elevation Monitoring (CASGEM) program and released the results in 2014. With the passage of SGMA, DWR redefined 54 groundwater basins based on requests for basin boundary modifications and classified the basins into four categories; high, medium, low, or very low priority. The SLO Basin was classified as a medium priority basin. The DWR reassessed the priority of the groundwater basins following the 2016 basin boundary modification, as required by the Water Code and documented the results in the SGMA 2019 Basin Prioritization (DWR, 2019). DWR followed the process and methods developed for the CASGEM 2014 Basin Prioritization and incorporated new data, to the extent data was available, and the amended the language of Water Code Section 10933(b)(8) (component 8) included an analysis of adverse impacts on local habitat and local streamflow. DWR prioritized the basins based on the following components specified in Water Code Section 10933(b): 1. The population overlying the basin or sub -basin. 2. The rate of current and projected growth of the population overlying the basin or sub -basin. 3. The number of public supply wells that draw from the basin or sub -basin. 4. The total number of wells that draw from the basin or sub -basin. 5. The irrigated acreage overlying the basin or sub -basin. 6. The degree to which persons overlying the basin or sub -basin rely on groundwater as their primary source of water. 7. Any documented impacts on the groundwater within the basin or sub -basin, including overdraft, subsidence, saline intrusion, and other water quality degradation. 8. Any other information determined to be relevant by the department, including adverse impacts on local habitat and local streamflow. With the addition of component 8, the SLO Basin moved from a medium priority basin to a high priority basin not in critical overdraft and is required to submit a GSP to DWR by January 31, 2022. The change in priority is inconsequential, as medium priority basins are also required to submit a GSP to DWR by January 31, 2022. Additional information about how each of these components were analyzed can be found in the 2019 SGMA Basin Prioritization Process and Results Document (DWR, 2019). DWR is required to provide updates on basin boundaries, basin priority and critically overdrafted basins every 5 years beginning in 2020 as part of the Bulletin 118 updates. 3 Page 45 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Introduction to the SLO Basin GSP CHORRO r` VALLEY," - I S VALLEY N CREEK WWI�rt`� � l 'Jf'"� iif11r7Tn G�� �� Froom CN" Sari Luis Obispo 1' Creek Watershed/ Greek T - uis r' 4 I aon� SAN LUIS OBISPO VALLEY \i Davehp—W Creek Explanation DWR Prioritization f Critically Overdrafted s RINCONADA High VALLEY Medium y , Very Low Adjudicated Basin }' SLO Basin and Watershed Boundaries t_py j 0 1 � � �`` San Luis Obispo Valley I�. Basin Boundary sd�ta'{ Pismo Creek Watershed �4 1 Pismo Creek C4 ' San Luis Obispo Creek 1�,� Watershed tqr Watershed 9e } - i, _ Surface Water Sources Al, Lakes and Reselviors Surface Water O1aek� , Faults -a; Q de ,; ,��Inferred Fault G�. s octal _ Fault Fad Lopez Lake ✓'p- f - ,.J ( y z HUASNA � SANTA MARIA ..�-z.., -" � VALLEY -RIVER VALLEY - l ARROYO GRANDE 31A vE- RaA i Spurce Esri, DigitalGlo be, Geo Eye, Earthstar Geographics, C.NES/Airbus DS, USDA. USGS, AeroGRID, IGN, and the GIS User Community Prepared for: ^' V 1 in2 ml Author. EC A Date: 8128201g ■N� 0 0.5 1 2 �Mi 9 1 2 4 SAN LUIS OBISPO VALLEY BASIN GSP w" References: 1. Crdinate System : NAI) Stateane Gali(omia V FIPS 0405 Feet oo D- it..ion_ Lambert Conformal Conic Plonic alum: North American 1983 2. 3_ Notes: 1, 2 , 3 Sari Luis Obispo Valley Basin and Surrounding Basins Figure 1-1 4 Page 46 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Agency Information (§ 354.6) 2 AGENCY INFORMATION (§ 354.6) On May 16, 2017, the City formed the City of San Luis Obispo Groundwater Sustainability Agency (City GSA) for the portion of the SLO Basin that lies within its city boundary. On May 23, 2017, the County formed the San Luis Obispo Valley Basin — County of San Luis Obispo Groundwater Sustainability Agency (County GSA) to cover all otherwise unrepresented areas within the SLO Basin. The County, City, the Edna Valley Growers Mutual Water Company (EVGMWC), the Varian Ranch Mutual Water Company (VRMWC), the Edna Ranch Mutual Water Company (ERMWC) and the Golden State Water Company (GSWC) (each referred to individually as a " Party" and collectively as the "Parties") entered into a Memorandum of Agreement Regarding Preparation of a GSP for the SLO Basin (MOA) effective as of January 25, 2018. The MOA's purpose is for the City and County, with input from the Participating Parties, to coordinate preparation of a single GSP for the entire SLO Basin pursuant to SGMA and other applicable provisions of law. Figure 2-1 shows the service area boundaries of each of the MOA Parties and the GSA areas. On October 16, 2018, the County GSA gave notice to DWR that it intends to develop a GSP in collaboration with the City GSA for the SLO Basin in accordance with California Water Code (CWC) Section 10727.8 and the Title 23, Section 353.6 of the California Code of Regulations (CCR). 2.1 AGENCIES NAMES AND MAILING ADDRESSES The following contact information is provided for each groundwater sustainability agency for the SLO Basin pursuant to California Water Code §10723.8. County of San Luis Obispo County Government Center, Room 206 San Luis Obispo, CA 93408 Attention: John Diodati , Public Works Interim Director City of San Luis Obispo Utilities Department 879 Morro Street San Luis Obispo, CA 93401-2710 Attention: Aaron Floyd, Utilities Director 5 Page 47 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Agency Information (§ 354.6) Chorro Reservoir ,reek Eto Lake t 5 E � r Warden Lake r Opp' .; f iPrefuJ-/� Laguna Lake i � r •.�_r�? f � J' ie",. x f _ \p Explanation MOA Participating Parties �. �_ f 'J Edna Valley Growers MWC 1 Edna Ranch MWC East Golden State WC _ Edna 1tr •' Varian Ranch MWC #aF ! %' 0/t 1�, 40 � 1 � � e� � � Groundwater Sustainability Agencies r . City of San Luis Obispo �� r v/ GSA County of San Luis Obispo C' ®GSA log OF 40 Surface Water Sources to Lakes and Reserviors { f ' " �,•�, Surface Water Ak-.OR OR r ►~ r a ek # Mkt" t , \ e� a4 e P t r lit2. 4A i 227 T , .•- f"-�;�. � ' � i 14 101 it '� ✓#• � � � �t �#- All J�v,l - 3 _ s Obis ! - + r 3 !�' i Cod ez Lake frr�e� ",� Lo�3ez �J ..��' - j ,. r _• Wr ; .... ." f t� ♦ _ i San Luis Obispo Bay 1 j itit J Source,�Esri, DigitalGlobe, Gec Eye, Earthstar Geographics, CNES1Airbus DS, USDA. USGS, AereGRID;1GN�and the GIS User=Co'mmuhity Prepared for: ^E I�! „n:,.5mi Author EC A 1,14�4' Date' 8128f2019 ■Ny 0 0.5 3 2 Mi 0 0.75 15 3 SAN LUIS OBISPO VALLEYBASIN GSP Km References: , ojectionaie Lambert IIAD nfo-1 3s,atePianeCa�or�iaVFip5aao5Fee, Lambert Conformal Conic Datum �alumNorth American 1983 2. 3- Notes: 2, 3. San Luis Obispo Valley Basin GSAAnd Participating Parties Figure 2-1 6 Page 48 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Agency Information (§ 354.6) 2.2 AGENCIES ORGANIZATION AND MANAGEMENT STRUCTURES The MOA establishes the Groundwater Sustainability Commission (GSC) as an advisory body to the GSAs and the terms under which the City GSA and County GSA will jointly develop a single GSP, in coordination with the GSC. The GSC consists of representatives of the GSAs and the Participating Parties (i.e., EVGMWC, VRMWC, ERMWC, and GSWC). Each member of the GSC shall be entitled to one vote on any matter under consideration by the GSC. All recommendations submitted by the GSC to the City Council and the County Board of Supervisors shall be supported by a majority of the members, except for the recommendation to adopt the GSP or any amendments which shall be supported by at least four of the members. City and County staff will collaboratively participate in developing a GSP through, among other things, providing guidance to consultant, coordinating with the GSC, and engaging SLO Basin users and stakeholders. Once the GSP is developed, it will be considered for adoption by the GSAs (i.e., City Council and County Board of Supervisors) and subsequently submitted to DWR for approval. The MOA automatically terminates upon approval of the GSP by DWR. The organization and management structures of each of the Parties are described in the following sections. The MOA does not specify the appointment of officer positions. However, Figure 2-2 shows the names of the appointed representative members and alternates and depicts the relationship of the GSAs and the Participating Parties and the overall governance structure for developing the GSP: Figure 2-2: Groundwater Sustainability Commission (GSC) Of IN CITY OF SLO GSA CO UNTY OF SLO GSA MYCHAL BOERMAN GSA STAFF DICK TZOU, PE Deputy Director of Water, Water Resources Engineer, City of Son Luis Obispo County of Son Luis Obispo IN EDNA VALLEY GROWERS MWC ADAM HILL ANDY PEASE BOB SCHIEBELHUT Member Member Chair BRUCE GIBSON AARON FLOYD GEORGE DONATI Alternate Alternate Alternate EDNA RANCH AND VARIAN RANCH MWC DENNIS FERNANDEZ Member JAMES LOKEY Afternate Golden State MARKZIMMER Vice Chair TOBY MOORE Alternate FA Page 49 of 1183 SLO Basin Groundwater Sustainability Plan Agency Information (§ 354.6) County of SLO and City of SLO 2.2.1 County of San Luis Obispo The County is a GSA and Party of the MOA. Members of the County Board of Supervisors sit on the GSC as a member and alternate member. The County is governed by a five -member Board of Supervisors representing five districts in the County. Board of Supervisor members are elected to staggered four-year terms. 2.2.2 City of San Luis Obispo The City is a GSA and Party of the MOA. A member of the City Council and the Director of Utilities sit on the GSC as a member and alternate member, respectively. The City is an incorporated charter city and operates under the "Council -Mayor -City Manager" form of municipal government. The five -member City Council consists of the directly -elected Mayor and four City Council Members. The Mayor is elected to a two-year term and Council Members are elected to four-year terms. 2.2.3 Other Participating Parties in the MOA 2.2.3.1 Edna Valley Growers Mutual Water Company EVGMWC is a Party of the MOA and its representative is designated as Chair of the GSC. EVGMWC provides water to the residents of unincorporated San Luis Obispo County within the SLO Basin. 2.2.3.2 Varian Ranch Mutual Water Company VRMWC is a Party of the MOA and a member of the GSC. VRMWC provides water to the residents of unincorporated San Luis Obispo County and serves an area within the SLO Basin as shown in Figure 2-1. 2.2.3.3 Edna Ranch Mutual Water Company ERMWC is a Party of the MOA and a member of the GSC. ERMWC provides water to the residents of unincorporated San Luis Obispo County and serves an area within the SLO Basin as shown in Figure 2-1. 2.2.3.4 Golden State Water Company GSWC is a Party of the MOA and its representative is designated as a Vice Chair of the GSC. GSWC is an Investor Owned Utility regulated by the California Public Utilities Commission (CPUC) and subject to federal Sarbanes-Oxley requirements that hold companies to the highest levels of transparency. CPUC's authority to regulate water, electric, natural gas, and other public utilities subject to its jurisdiction derives from the California state constitution. 2.3 AUTHORITY OF AGENCIES The GSAs developing this coordinated GSP were formed in accordance with the requirements of California Water Code §10723 et seq. The resolutions of formation for the GSAs and the Memorandum of Understanding (MOA) are included in Appendices A - C. The specific legal authorities for GSA formation and GSP implementation are summarized below. 2.3.1 Groundwater Sustainability Agencies "Local agency" is defined pursuant to CWC§ 10721 as a local public agency that has water supply, water management, or land use responsibilities within a groundwater basin. 2.3.1.1 County of San Luis Obispo The County was created as described in Government Code Section 460 which states that the state is divided into counties, the names, boundaries and territorial subdivisions of 13 Page 50 of 1183 SLO Basin Groundwater Sustainability Plan Agency Information (§ 354.6) County of SLO and City of SLO which are declared in Title 3 of the Government Code. The County has land use authority over the unincorporated areas of the county, including areas overlying the SLO Basin. The County is therefore a local agency under CWC§ 10721(n) with the authority to establish itself as a GSA. Upon establishing itself as a GSA, the County retains all the rights and authorities provided to GSAs under CWC§ 10725 et seq. The City and the County shall each be responsible for adopting the GSP and implementing the GSP within their respective service areas. 2.3.1.2 City of San Luis Obispo The City is incorporated under the laws of the State of California. The City provides water supply and land use planning services to its residents. The City is therefore a local agency under CWC§ 10721(n) with the authority to establish itself as a GSA. Upon establishing itself as a party of the GSA, San Luis Obispo retains all the rights and authorities provided to GSAs under CWC§ 10725 et seq. The City and the County shall each be responsible for adopting the GSP and implementing the GSP within their respective service areas. 2.3.2 Memorandum of Agreement The MOA Parties entered into the MOA effective as of January 25, 2018. The MOA establishes the GSC as an advisory body to the GSAs and the terms under which the City GSA and County GSA will jointly develop a single GSP, in coordination with the GSC pursuant to SGMA and other applicable provisions of law. The GSC members consists of representatives of the GSAs and the Participating Parties (i.e., EVGMWC, VRMWC, ERMWC, and GSWC). City and County staff will collaboratively participate in developing a GSP through, among other things, providing guidance to the consultant, coordinating with the GSC, and engaging SLO Basin users and stakeholders. Each GSC member has one vote on the GSC. The County Board of Supervisors and the City Council may approve or reject any advisory opinion submitted by the GSC provided that in every case that the County Board of Supervisors or City Council rejects an advisory opinion of the GSC related to the contents or adoption of the GSP it shall do so only after holding a public hearing, at which time the members of the GSC shall have the right to appear and address the City Council and the County Board of Supervisors. The MOA automatically terminates upon approval of the GSP by DWR. A copy of the MOA is included in Appendix B. 2.3.3 Coordination Agreements Only a single GSP is developed by the City and County GSAs to cover the entire SLO Basin. Therefore, no coordination agreements with other GSAs are necessary because there is no multiple GSPs. 2.4 CONTACT INFORMATION FOR PLAN MANAGER The plan manager is to be determined. 9 Page 51 of 1183 SLO Basin Groundwater Sustainability Plan References County of SLO and City of SLO 3 REFERENCES Carollo. 2012. San Luis Obispo County Master Water Report. 2012. City of San Luis Obispo. 2016. 2015 Urban Water Management Plan. 2016. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. DWR. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. —. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. —. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. 10 Page 52 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO 4 APPENDICES APPENDIX A - CITY OF SAN LUIS OBISPO RESOLUTION TO FORM GSA 11 Page 53 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO RESOLUTION NO.10796 (2017 SERIES) A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF SAN LUIS OBISPO, CALIFORNIA, AUTHORIZING THE CITY TO BECOME A GROUNDWATER SUSTAINABILITY AGENCY FOR THE SAN LUIS OBISPO VALLEY GROUNDWATER BASIN FOR THE AREA THAT LIES BENEATH AND WITHIN THE JURISDICTIONAL BOUNDARIES OF THE CITY OF SAN LUIS OBISPO WHEREAS, in 2014 the California Legislature and the Governor passed into law the Sustainable Groundwater Management Act (SGMA) for local management of groundwater resources in California through the formation of Groundwater Sustainability Agencies (GSAs) and through preparation and implementation of Groundwater Sustainability Plans (GSPs); and WHEREAS, the City overlies a portion of the San Luis Obispo Valley Groundwater Basin (SLOVGB), which is subject to SGMA, and thus one or more GSAs must be formed for the SLOVGB by June 30, 2017, or the SLOVGB may be subject to regulation by the State Water Resources Control Board; and WHEREAS, the City is a "local agency' as that term is defined by SGMA, and as such is authorized to form a GSA to manage groundwater resources in the SLOVGB and within the City's jurisdictional boundaries in accordance with SGMA and other applicable laws and authorities; and WHEREAS, the City desires to form a GSA to manage groundwater resources in the SLOVGB beneath and within the City's jurisdictional boundaries; and WHEREAS, the City intends that its GSA will work cooperatively with the other GSAs that have formed or will be formed in the SLOVGB to prepare one or more GSPs by January 31, 2022, so that groundwater resources in the SLOVGB will be properly managed and sustainable in accordance with the provisions of SGMA; and WHEREAS, it is essential that the City form this GSA because SGMA grants GSAs substantial additional powers and authorities to ensure sustainable groundwater management. Acting as the GSA within the City's jurisdictional boundaries will, among other things, confirm the City's role as the local groundwater management agency, ensure access to SGMA authorities, and preserve access to grant funding and other opportunities that may be available to GSAs; and WHEREAS, pursuant to the requirements of SGMA, the City held a public hearing on this date after publication of notice pursuant to California Government Code section 6066 to consider adoption of this Resolution. R 10796 12 Page 54 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO Resolution No. 10796 (2017 Series) Page 2 NOW, THEREFORE, BE IT RESOLVED by the Council of the City of San Luis Obispo as follows: SECTION 1. All of the above recitals are true and correct and incorporated herein by reference. SECTION 2. The City of San Luis Obispo hereby elects to become the Groundwater Sustainability Agency in accordance with the Sustainable Groundwater Management Act over the portion of the San Luis Obispo Valley Groundwater Basin which lies under and within the jurisdictional boundaries of the City of San Luis Obispo. SECTION 3. The City Manager is authorized and directed to submit a notice of this Resolution along with all other required information to the California Department of Water Resources in accordance with the Sustainable Groundwater Management Act. SECTION 4. The City Groundwater Sustainability Agency shall consider the interests of aii beneficial uses and users of the groundwater within the junsdictional boundaries of the City and will develop an outreach program for all such stakeholders. The City Groundwater Sustainability Agency will continue to coordinate with other local agencies and stakeholders that overlie the San Luis Obispo Valley Groundwater Basin in order to manage groundwater resources. SECTION 5. The City Groundwater Sustainability Agency shall establish and maintain a list of persons interested in receiving notices regarding the City's involvement in the preparation of one or more Groundwater Sustainability Plans in the San Luis Obispo Valley Groundwater Basin, where any person may request in writing to be placed on the City's list of interested persons. SECTION 6. Resolution Number 10777 (2017 Series) is hereby repealed. 13 Page 55 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO Resolution No. 10796 (2017 Series) Page 3 Upon motion of Council Member Pease, seconded by Council Member Christianson, and on the following roll call vote: AYES: Council Members Christianson, Gomez, and Pease Vice Mayor Rivoire and Mayor Harmon NOES: None ABSENT: None The foregoing resolution was adopted this 16`h day of May, 2017, /az'�4- Ma r Fl di Harmon ATTEST: Carrie Gallagher City Clerk *hristine ED AS T FORM: Dietrickney IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the City of San Luis Obispo, California, this 2! k6_ day of . , 2017. Carrie Gallagher City Clerk 14 Page 56 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices FAUUDI►III Kq:IMK11110Y1 &OIcyALII U1F-Y17:]Ry101.1 WO ILIA 9to] 0a111T1 11,10K IYA 15 Page 57 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO GSA Formation Exhibit C - Resolution forming the San Luis Obispo Valley Basin - County of SLO GSA County of San Luis Obispo, State of California Tuesday, May 23, 2017 PRESENT, Supervisors Bruce S. Gibson, Adam Hill, Lynn Compton, Debbie Arnold, and Chairperson John Peschong ABSENT: None RESOLUTION NO, 2017-146 RESOLUTION FORMING THE SAN LUIS OBISPO VALLEY BASIN - COUNTY OF SAN LUIS OBISPO GROUNDWATER SUSTAINABILITY AGENCY AND FINDING THAT THE PROJECT IS EXEMPT FROM SECTION 21000 ET SEQ. OF THE CALIFORNIA PUBLIC RESOURCES CODE (CEQA) The following Resolution is hereby offered and read: WHEREAS, in 2014, the California Legislature adopted, and the Governor signed into law, three bills (SB 1168, AB 1739, and SB 1319) collectively referred to as the Sustainable Groundwater Management Act (SGMA) (Water Code §§ 10720 et seq.), that became effective on January 1, 2015, and that have been subsequently amended; and WHEREAS, the intent of SGMA, as set forth in Water Code Section 10720.1, is to provide for the sustainable management of groundwater basins at a local level by providing local groundwater agencies with the authority, and technical and financial assistance necessary, to sustainably manage groundwater; bnd WHEREAS, SGMA requires the formation of Groundwater Sustainability Agencies (GSAs) for the purpose of achieving groundwater sustainability through the adoption and implementation of Groundwater Sustainability Plans (GSPs) for all medium and high priority basins as designated by the California Department of Water Resources (DWR); and WHEREAS, SGMA requires that a local agency or collection of agencies decide to become a GSA for all medium and high priority basins on or before June 30, 2017 and that the GSA or GSAs for basins DWR has not designated as "subject to critical conditions of overdraft" develop a GSP or coordinated GSPs on or before January 31, 2022; and WHEREAS, the San Luis Obispo Valley Groundwater Basin (Basin) has been designated by DWR as a medium priority basin, but not subject to critical conditions of overdraft; and 1 of 5 16 Page 58 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices WHEREAS, the County of San Luis Obispo and the City of San Luis Obispo are each a "local agency" within the Basin as defined in Water Code Section 10721(n) and thus are eligible to form GSAs; and WHEREAS, it is anticipated that the City of San Luis Obispo will form a GSA for the portion of the Basin within the City boundary; and WHEREAS, the County of San Luis Obispo intends to form a GSA to cover all other portions of the Basin; and WHEREAS, SGMA authorizes certain entities, specifically water corporations regulated by the Public Utilities Commission and mutual water companies, to participate in a GSA through a memorandum of agreement or other legal agreement; and WHEREAS, a number of such entities overlie the Basin, including the Edna Valley Growers Mutual Water Company, the Edna Ranch Mutual Water Company, the Varian Ranch Mutual Water Company and fhe Golden State Water Company, and it is anticipated that such entities will desire to enter into a memorandum of agreement with the County and City of San Luis Obispo establishing a process by which such entities will participate in the preparation of the GSP for the Basin; and WHEREAS, the County of San Luis Obispo published a notice of public hearing consistent with the requirements contained within Water Code Section 10723(b); and WHEREAS, the Board of Supervisors conducted such a public hearing on May 23, 2017; and WHEREAS, the County of San Luis Obispo is committed to the sustainable management of groundwater within the Basin and intends to consider the interests of all beneficial users and uses of groundwater within the Basin through, among other things, coordination with the City of San Luis Obispo bnd the entities eligible to participate in SGMA as described above. NOW, THEREFORE, BE IT RESOLVED AND ORDERED by the Board of Supervisors of the County of San Luis Obispo, State of California, that; Section 1: The foregoing recitals are true and correct and are incorporated herein by reference. Section 2: The County of San Luis Obispo hereby decides to become the GSA for, and undertake sustainable groundwater management within, the Basin, with the exception of the portions of the Basin located within the City of San Luis Obispo ("GSA Boundary"). The GSA shall be known as the San Luis Obispo Valley Basin - County of San Luis Obispo Groundwater Sustainability Agency, and a map of the GSA Boundary is attached hereto as Exhibit A and incorporated herein. Section 3: The Director of Public Works of the County of San Luis Obispo, or designee, Is hereby authorized and directed to submit notice of adoption of this Resolution in addition to all other information required by SGMA, including but not limited to, all 2of5 17 Page 59 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO to wit: Appendices information required by Water Code Section 10723.8, to DWR, and to develop and maintain an interested persons list as described in Water Code Section 10723.4 and a list of interested parties as described in Water Code Section 10723.8(a)(4). Section 4: The Director of Public Works of the County of San Luis Obispo, or designee, is hereby authorized and directed to take such other and further actions as may be necessary or appropriate to implement the intent and purposes of this Resolution. Section 5: The Board of Supervisors finds that the adoption of this Resolution is exempt from the requirements of the California Environmental Quality Act (Public Resources Code §§ 21000 et seq.) (CEQA) pursuant to Section 15061(b)(3) of the CEQA Guidelines. Section 6: The Environmental Coordinator of the County of San Luis Obispo is hereby directed to file a Notice of Exemption in accordance with the provisions of CEQA. Upon motion of Supervisor Hill, seconded by Supervisor Gibson, and on the following roll call vote, AYES: Supervisors Hill, Gibson, Compton, Arnold and Chairperson Peschong NOES: None ABSENT: None ABSTAINING: None the foregoing resolution is hereby adopted on the 23" day of May, 2017. E ATTEST: TOMMY GONG Clerk of the Board of Supervisors By, Annette Ramirez r Deputy Clerk ([SEAL] lohn Peschong Chairperson of the Board of Supervisors 3of$ 18 Page 60 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPROVED AS TO FORM AND LEGAL EFFECT: RITA L. NEAL County Counsel By: /s/ Erica Stuckey Deputy County Counsel Dated:.May 1 2017 LAWater Resources\2017\May\BOS\5an Luis Obispo Valley Basin GSA\SLO Valley Basin rsl.docx CB:jb Appendices STATE OF CALIFORNIA, ) ) ss. COUNTY OF SAN LUIS OBISPO ) I, Tommy Gong, County Cleric and ex-officio Clerk of the Board of Supervisors, in and for the County of San Luis Obispo, State of California, do hereby certify the foregoing to be a full, true and correct copy of an order made by the Board of Supervisors, as the same appears spread upon their minute book. WITNESS my hand and the seas of said Board of Supervisors, affixed this ' .Vd day of May, 2017. Tommy Gong County Clerk and Ex-Officio Clerk of the Board of Supervisors (SEAL) / By: l Deputy Clerk �— dof5 19 Page 61 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO /:1»D1►III k.4[=aIDIa[I],7:1►1D111u[I]Y/:�elN�l�lul�l►�YIO�N�1�:1.7:�Y[Il►[I]Y<e'�y� Appendices 20 Page 62 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices MEMORANDUM OF AGREEMENT REGARDING PREPARATION OF A GROUNDWATER SUSTAINABILITY PLAN FOR THE SAN LUIS OBISPO VALLEY GROUNDWATER BASIN This Memorandum of Agreement ("MON') is entered into by and between the City of San Luis Obispo ("City'), the County of San Luis Obispo ("County'), the Edna Valley Growers Mutual Water Company ("EVGMWC"), the Varian Ranch Mutual Water Company ("VRMWC' ), the Edna Ranch Mutual Water Company ("ERMWC") and the Golden State Water Company ("GSWC") (each referred to individually as a "Party" and collectively as the "Parties") for purposes of coordinating preparation of a single groundwater sustainability plan for the San Luis Obispo Valley Groundwater Basin. Recitals WHEREAS, on September 16, 2014, GovernorJerry Brown signed into law Senate Bills 1168 and 1319 and Assembly Sill 1739, known collectively as the Sustainable Groundwater Management Act ("SGMA"), which became effective on January 1, 2015 and which have been and may continue to be amended from time to time; and WHEREAS, SGMA requires the establishment of a groundwater sustainability agency ("GSA") or agencies for all basins designated as medium- or high -priority by the Department of Water Resources ("DWR") on or before June 30, 2017; and WHEREAS, SGMA further requires the adoption of a groundwater sustainability plan ("GSP") or coordinated GSPs for all basins designated by DWR as medium- or high -priority and not subject to critical conditions of overdraft on or before January 31, 2022; and WHEREAS, DWR has designated the San Luis Obispo Valley Groundwater Basin (Basin No. 3-9) ("Basin") as a medium -priority basin not subject to critical conditions of overdraft; and WHEREAS, the County and the City have each decided to become the GSA within their respective service areas overlying the Basin and have informed DWR of their decision and intent to undertake sustainable groundwater management therein; and WHEREAS, the County and the City desire to collectively develop a single GSP to sustainably manage the Basin; and WHEREAS, the County and the City further desire to include the other Parties to this MOA who each constitute entities eligible to participate in a GSA (sometimes referred to individually as a "Participating Party" or collectively as the "Participating Parties") in the development of the GSP through the creation of the Groundwater Sustainability Commission. Page 1 of 9 21 Page 63 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO NOW, THEREFORE, it is mutually understood and agreed as follows: Section 1 Purpose This MOA is entered into by the Parties for the purpose of establishing the manner in which the City and the County, with input from the Participating Parties, will coordinate in the development of a single GSP for the Basin that will be considered for adoption by the City Council and the County Board of Supervisors and subsequently submitted to DWR for approval. This MOA may also serve as the basis for continued cooperation among the City and the County in the management of the Basin during the period between adoption of the GSP by the City Council and the County Board of Supervisors and approval of the GSP by DWR. As more specifically set forth in Section 10.3 below, this MOA shall automatically terminate upon DWR's approval of the GSP for the Basin. Section 2 Term This MOA shall become effective on the date that the last of the six (6) Parties signs ("Effective Date") and shall remain in effect until terminated in accordance with Section 9.2 or Section 10.3 below. Section 3 City and County Roles and Responsibilities 3.1 The City and the County shall work jointly to meet the objectives of this MOA. 3.2 The City and the County shall retain the services of a consultant(s) to meet the objectives of this MOA, including, but not limited to, preparation of a GSP for the Basin in accordance with the provisions set forth in Section 7 below. 3.3 The City and the County shall each designate a staff person(s) to participate in the development of the GSP and related technical studies through, without limitation, the provision of guidance and available data, in coordination with the consultant(s), and to administer the Groundwater Sustainability Commission (e.g. to, among other things, timely publish all agendas and take minutes). 3.4 The City and the County shall each be responsible for adopting the GSP and implementing the GSP within their respective service areas. Notwithstanding the foregoing, nothing contained in this MOA shall be construed as obligating either the City Council or the County Board of Supervisors to adopt the GSP developed pursuant to this MOA or as preventing either the City Council or the County Board of Supervisors from adopting the GSP developed under this MOA in the event that the other elects not to adopt it or in the event that the Groundwater Sustainability Commission fails to recommend approval. Page 2 of 9 22 Page 64 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO 3.5 The City and the County may lead certain Basin -wide public outreach and stakeholder involvement to improve development of the GSP. 3.6 The City shall be responsible for taking all legally required actions associated with its appointment of the member and alternate member to the Groundwater Sustainability Commission representing the City as set forth in Section 4.5, including, without limitation, all applicable requirements under the Maddy Act (Government Code H 54970 et seq.) and the County shall be responsible for taking all such actions associated with its appointment of the member and alternate member to the Groundwater Sustainability Commission representing the County and its confirmation of the members and alternate members to the Groundwater Sustainability Commission representing the Participating Parties as set forth in Section 4.4 and Section 4.3, respectively. Section 4 Establishment of the Groundwater Sustainability Commission 4.1 The City and the County hereby establish the Groundwater Sustainability Commission to serve as an advisory committee to the City Council and the County Board of Supervisors in connection with preparation of the GSP and interim Basin management actions subject to each Participating Party making its required contributions under Section 6(B). 4.2 The Groundwater Sustainability Commission shall be composed of five (5) members: one (1) member representing the City, one (1) member representing the County, one (1) member representing EVGMWC, one (1) member collectively representing VRMWC and ERMWC and one (1) member representing GSWC. 4.3 Each of the Participating Parties shall nominate a member and an alternate member to represent it on the Groundwater Sustainability Commission subject to confirmation by the County Board of Supervisors with the exception that VRMWC and ERMWC shall jointly nominate a member and an alternate member to represent them subject to confirmation by the County Board of Supervisors. Said members shall serve at the pleasure of the County Board of Supervisors and may be removed at any time provided that the County Board of Supervisors shall have no authority to replace a removed member with an individual who has not been nominated by the relevant Participating Parry or collection of Participating Parties. 4.4 The County Board of Supervisors shall appoint the member and alternate member representing the County and said members shall serve at the pleasure of the County Board of Supervisors. 4.5 The City Council shall appoint the member and alternate member representing the City and said members shall serve at the pleasure of the City Council. Page 3 of 9 23 Page 65 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices 4.6 All meetings of the Groundwater Sustainability Commission shall be conducted in accordance with the Ralph M. Brown Act (Government Code §§ 54950 et seq.). 4.7 A majority of the members of the Groundwater Sustainability Commission shall constitute a quorum for purposes of transacting business, except that less than a quorum may vote to adjourn the meeting. 4.8 Each member of the Groundwater Sustainability Commission shall be entitled to one (1) vote on any matter under consideration by the Groundwater Sustainability Commission. 4.9 All advisory opinions submitted by the Groundwater Sustainability Commission to the City Council and the County Board of Supervisors shall be supported by a majority of the members, except for the recommendation to adopt the GSP or any amendments thereto which shall be supported by at least four (4) of the members. 4.10 The County Board of Supervisors and the City Council may approve or reject any advisory opinion submitted by the Groundwater Sustainability Commission provided that in every case that the County Board of Supervisors or City Council rejects an advisory opinion of the Groundwater Sustainability Commission related to the contents or adoption of the GSP it shall do so only after holding a public hearing, at which time the members of the Groundwater Sustainability Commission shall have the right to appear and address the City Council and the County Board of Supervisors. 4.11 None of the members or alternate members shall be entitled to any compensation from the County or the City for their service on the Groundwater Sustainability Commission. Section 5 Establishment of Additional Advisory Committees The City Council and the County Board of Supervisors may from time to time jointly establish one or more additional advisory committees or establish standing or ad hoc committees to assist in carrying out the purposes and objectives of this MOA. Without limiting the foregoing, it is anticipated that the City Council and the County Board of Supervisors will establish a stakeholder advisory committee to the Groundwater Sustainability Commission to consider the interests of beneficial uses and users not already represented on the Groundwater Sustainability Commission consistent with Water Code Section 10723.2. Page 4 of 9 24 Page 66 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Section 6 Funding The City and the County agree to jointly fund the costs associated with implementation of this MOA in accordance with and subject to the following: A. Within sixty (60) days of the Effective Date and prior to each anniversary of the Effective Date, City and County staff shall prepare an annual budget for the GSAs to implement this MOA for approval by the City Council and the County Board of Supervisors. 8, Each of the Participating Parties shall be responsible for contributing the following funds to help defray the costs of the Groundwater Sustainability Commission and in consideration for their participation thereon within thirty (30) days of the Effective Date and within thirty (30) days of each anniversary of the Effective Date: EVGMWC $28,200 VRMWC $4,550 ERMWC $4,550 GSWC $12,700 C. Subject to City Council and County Board of Supervisor approval of the annual budget, the City and County agree to fund the annual budget (less the contributions set forth in Section 6(B)) In accordance with the percentage allocations set forth below. Notwithstanding the foregoing and Section 10.1, the City Council and the County Board of Supervisors may amend said percentage allocations without the agreement of the Participating Parties. County 70% City 30% D. It is anticipated that the vast majority of budgeted costs to be paid by the City and the County will involve costs for consultant services. Consequently, most City and County contributions will be paid in the manner described in Section 7 below. Section 7 Retention of Consultants 7.1 The County agrees to act as the contracting agent to retain the services of a consultant(s) as described in Section 3.2 above. 7.2 Notwithstanding the foregoing, the County agrees that the City and one (1) member of the Groundwater Sustainability Commission not representing the City or the County designated by the Groundwater Sustainability Commission shall be included in the selection of any consultant retained by the County pursuant to this MOA. Mores pecifically, Page 5 of 9 Appendices 25 Page 67 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices a staff representative from the City and the designated member of the Groundwater Sustainability Commission shall be given an opportunity to review and approve all requests for proposals prior to their release and to participate in the various stages of the selection process, including, but not limited to, review of proposals and participation on interview panels. 7.3 All consultant contracts entered into by the County pursuant to this MOA shall include the following: (1) a provision requiring that the consultant name the City as an additional insured, (2) an expected spend plan estimating the amount of the not to exceed contract amount that the consultant expects to invoice each month, and (3) a provision requiring that the consultant calculate both the County and City's share of each invoice consistent with Section 6(C) and send monthly invoices to both the County and the City showing the foregoing calculation. 7.4 Both the City and the County shall be responsible for remitting payment of their share of each monthly invoice directly to the consultant within thirty (30) days of receipt or within the time frame otherwise set forth in the consultant contract. Section 8 Notice 8.1 To provide for consistent and effective communication among the Parties, each Party shall designate a representative as its central point of contact on matters relating to this MOA. 8.2 All notices, statements, or payments related to this MOA shall be deemed to have been duly given if in writing and delivered electronically, personally or mailed by first- class, registered or certified mail to the Parties at the addresses set forth in Exhibit A. The Parties may update Exhibit A from time to time without formal amendment to this MOA. Section 9 Withdrawal and Termination 9.1 Any Participating Party may unilaterally withdrawal from this MOA without causing or requiring termination of this MOA. Withdrawal shall become effective upon thirty (30) days written notice to the remaining Parties' designated addresses as listed in Exhibit A. A Participating Party that has withdrawn from this MOA shall remain obligated to pay its allocation of the current annual budget. If a Participating Party withdraws, the Groundwater Sustainability Commission shall automatically be reconstituted to no longer include a member or alternate member representing the withdrawing Participating Party. In addition, the withdrawing Participating Partys annual contribution as set forth in Section 6(B) for all subsequent years shall be allocated among the remaining Participating Parties on a pro rata basis. Page 6 of 9 26 Page 68 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO 9.2 This MCA maybe terminated by either the City or the County upon thirty (30) days written notice to all Parties' designated addresses as listed in Exhibit A. Upon termination, any unused portion of the cost contributions described in Section 6(8) and Section 6(C) as of the effective date of termination shall be returned to each Parry on a pro rata basis. If the City terminates this MCA, it shall remain obligated to pay its cost share obligation under any existing consultant contract entered into by the County pursuant to this MCA. Section 10 Miscellaneous 10.1 Subject to the exception set forth in Section 6(C), this MCA may be amended only by unanimous written consent of all current Parties. 10.2 This MCA may be executed in counterparts. 10.3 This MOA shall automatically terminate upon DWWs approval of the adopted GSP. Depending on the content of the GSP, the Parties may decide to enter into a new agreement to coordinate GSP implementation. 10.4 This MCA is made in the State of California, under the Constitution and laws of said State and is to be so construed. 10.5 If any provision of this MCA is determined to be invalid or unenforceable, the remaining provisions shall remain in full force and unaffected to the fullest extent permitted by law and regulation. 10.6 This MCA constitutes the sole, entire, integrated and exclusive agreement between the Parties regarding the contents herein. Any other contracts, agreements, terms, understandings, promises or representations not expressly set forth or referenced in this writing are null and void and of no force and effect. 10.7 The Parties agree and acknowledge that this MCA has been developed through negotiation, and that each Party has had a full and fair opportunity to revise the terms of this MOA. Consequently, the normal rule of construction that any ambiguities are to be resolved against the drafting party shall not apply in construing or interpreting this MCA. [signatures to follow on next page] Page 7 of 9 27 Page 69 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO COUJY;lr R�1-1-115 OBISPO By: B Its: 10 Date: Date APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL EFFECT: By: By: Its: Its: Date: Date: n6;;2!' EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: Page 8 of 9 Appendices m Page 70 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated befow. CITY OF SAN LUIS OBISPO COUNTY OF SAN LUIS OBISPO By: By: JOHN PESCHOt Its: Its:UAR00berWdOof Date: Date: MUO)-y Q i Me) APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL EFFECT: SST: Tommy Gong, County Clerk -Recorder and Ex-Offsclo.Clerk of the Board of Supervisors By By S{iNDY C SMENS Its: Its: 8yDgmtyCkvk Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WAT R COMPANY WATER COMPANY B y. By: - I - Its: Its: Date: I { Date: EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: Page 8 of 9 29 Page 71 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF So LUIS O t�0 COUNTY OF SAN LUIS OBISPO By: By: Its: Its Date: ( Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGTEFTP: LEGAL EFFECT: By: By:Its: o.;�h� Pti of ,y Its: Dat4: u— Date: AL:;V• b, 2O/�- EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: Page 8 of 9 30 Page 72 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXHIBIT A PARTY ADDRESS LEST County of San Luis Obispo County Government Center, Room 206 San Luis Obispo, CA 93408 Attention: Wade Horton, Public Works Director City of San Luis Obispo Utilities Department 879 Morro Street San Luis Obispo, CA 93401-2710 Attention: Carrie Mattingly, Utilities Director Edna Valley Growers Mutual Water Company 4910 Edna Road San Luis Obispo, CA 93401 Attention: Bob Schiebelhut, President Varian Ranch Mutual Water Company 2060 Varian Circle Arroyo Grande, CA 93420 Attention: James Lokey Edna Ranch Mutual Water Company 5665 Edna Ranch Circle San Luis Obispo, CA 93401 Attention: Andy Mangano Golden State Water Company 2330 A Street, Suite A Santa Maria, CA 93455 Attention: General Manager, Coastal District Page 9 of 9 Appendices 31 Page 73 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXHIBIT A PARTY ADDRESS LIST County of San Luis Obispo County Government Center, Room 206 San Luis Obispo, CA 93408 Attention: Wade Horton, Public Works Director City of San Luis Obispo Utilities Department 879 Morro Street San Luis Obispo, CA 93401-2710 Attention: Carrie Mattingly, Utilities Director Edna Valley Groaners Mutual Water Company 4910 Edna Road San Luis Obispo, CA 93401 Attention: Bob Schiebelhut, President Varian Ranch Mutual Water Company 2060 Varian Circle Arroyo Grande, CA 93420 Attention: James Lokey Edna Ranch Mutual Water Company 5665 Edna Ranch Circle San Luis Obispo, CA93401 Attention: Andy Mangano Golden State Water Company 2330 A Street, Suite A Santa Maria, CA 93455 Attention: General Manager, Coastal District Page 9 of 9 Appendices 32 Page 74 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO COUNTY OF SAN LUIS OBISPO By: By: Its: Its: Date: Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL EFFECT: By: By: Its: Its: Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER OMPANY J�Ci Its: I Date: Date: 4� EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: Page 8 of 9 33 Page 75 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO IN WITNESS WHEREOF, the Parties. have executed this MOA by authorized officials thereof on the dates indicated below. CLTY OF SANF LFMS OB'FSF0 COUNTY OF SAN E +UTS 0915100 By: By: Its: Its: Date: Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL'EFFIECT: By: By: lts: Its: Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDfVA NCH MUTUAL GOLDEN STATE WATER COMPANY WAFR-PANY- BY: By: Its: Its: Date: 1 J ► iE i Date: Page 8 0f:9 34 Page 76 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO COUNTY OF SAN LUIS OBISPO By: By: Its: Its: Date: Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL EFFECT: By: By: Its: Its: Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: apt; Its: Its: Sr, ViG,L PKb1cLci4+ Date: Date: ov i'r fLOi" j Page 8 of 9 35 Page 77 of 1183 Draft Groundwater Sustainability Plan Chapter 3 — Description of Plan Area and Chapter 4 - Basin Setting forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by �WSC WATER SYSTEMS CONSULTING, INC. CHI' GECansulsante �� Stillwater ScienCeS watersolutioos,Inc. 12/2/2019 Page 78 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO TABLE OF CONTENTS Table of Contents Tableof Contents........................................................................................................................................... i Listof Figures.............................................................................................................................................. vii Tables......................................................................................................................................................... viii Appendices................................................................................................................................................... ix Listof Terms Used......................................................................................................................................... x ExecutiveSummary....................................................................................................................................... 1 3 Description of Plan Area (§ 354.8)....................................................................................................... 2 3.1 SLO Basin Introduction.................................................................................................................. 2 3.2 Adjudicated Areas.........................................................................................................................5 3.3 Jurisdictional Areas....................................................................................................................... 5 3.3.1 Federal Jurisdictions.............................................................................................................. 5 3.3.2 Tribal Jurisdiction.................................................................................................................. 5 3.3.3 State Jurisdictions................................................................................................................. 5 3.3.4 County Jurisdictions..............................................................................................................5 3.3.5 City and Local Jurisdictions................................................................................................... 5 3.3.6 Special Districts..................................................................................................................... 5 3.4 Land Use........................................................................................................................................5 3.4.1 Water Source Types.............................................................................................................. 9 3.4.2 Water Use Sectors............................................................................................................... 11 3.5 Density of Wells.......................................................................................................................... 13 3.6 Existing Monitoring and Management Programs.......................................................................18 3.6.1 Groundwater Monitoring....................................................................................................18 3.6.1.1 Groundwater Level Monitoring.................................................................................18 3.6.1.2 Groundwater Quality Monitoring..............................................................................18 3.6.1.3 Surface Water Monitoring.......................................................................................... 20 3.6.1.4 Climate Monitoring.....................................................................................................20 3.6.2 Existing Management Plans................................................................................................24 3.6.2.1 SLO Basin Characterization and Monitoring Well Installation....................................24 3.6.2.2 San Luis Obispo County Master Water Report(2012)................................................24 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014).........25 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan (2016) ....................... 25 3.6.3 Existing Groundwater Regulatory Programs........................................................................ 25 3.6.3.1 Groundwater Export Ordinance (2015)...................................................................... 25 Page 79 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.6.3.2 Well Ordinances, County and City.............................................................................. 25 3.6.3.3 Countywide Water Conservation Program Resolution 2015-288 (2015) ................... 26 3.6.3.4 Agricultural Order R3-2017-002 (2017)...................................................................... 26 3.6.3.5 Water Quality Control Plan for the Central Coast Basins (2017)................................ 26 3.6.3.6 California DWR Well Standards (1991)....................................................................... 26 3.6.3.7 Requirements for New Wells(2017)........................................................................... 27 3.6.3.8 Title 22 Drinking Water Program(2018)..................................................................... 27 3.6.3.9 Waterway Management Plan — San Luis Obispo Creek Watershed (2003)................27 3.6.3.10 Incorporation Into GSP................................................................................................ 27 3.6.3.11 Limits to Operational Flexibility..................................................................................27 3.7 Conjunctive Use Programs..........................................................................................................28 3.8 Land Use Plans............................................................................................................................ 28 3.8.1 City of San Luis Obispo General Plan.................................................................................. 28 3.8.2 County of San Luis Obispo General Plan............................................................................. 29 3.8.3 Los Ranchos/Edna Village Plan............................................................................................30 3.8.4 Plan Implementation Effects on Existing Land Use.............................................................31 3.8.5 Plan Implementation Effects on Water Supply................................................................... 32 3.8.6 Well Permitting................................................................................................................... 32 3.8.7 Land Use Plans Outside of Basin......................................................................................... 32 3.9 Management Areas..................................................................................................................... 32 3.9.1 Reason for Creation............................................................................................................ 32 3.10 Additional GSP Elements, if Applicable....................................................................................... 32 4 Basin Setting (§ 354.14).....................................................................................................................33 4.1 Basin Topography and Boundaries............................................................................................. 33 4.2 Primary Users of Groundwater...................................................................................................40 4.3 Soils Infiltration Potential............................................................................................................40 4.4 Regional Geology........................................................................................................................ 42 4.4.1 Regional Geologic Structures..............................................................................................42 4.4.2 Geologic Formations within the Basin................................................................................42 4.4.2.1 Alluvium......................................................................................................................46 4.4.2.2 Paso Robles Formation...............................................................................................46 4.4.2.3 Pismo Formation......................................................................................................... 46 4.4.3 Geologic Formations Surrounding the Basin......................................................................47 4.4.3.1 Monterey Formation...................................................................................................47 4.4.3.2 Obispo Formation.......................................................................................................47 ii Page 80 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 4.4.3.3 Franciscan Assemblage...............................................................................................47 4.5 Principal Aquifers and Aquitards................................................................................................48 4.5.1 Cross Sections..................................................................................................................... 48 4.5.2 Aquifer Characteristics........................................................................................................ 65 4.5.3 Aquitards.............................................................................................................................70 4.6 Surface Water Bodies.................................................................................................................. 70 4.7 Subsidence Potential...................................................................................................................71 5 Groundwater Conditions (§ 354.16).................................................................................................. 5.1 Groundwater Elevations and Interpretation.............................................................................. 5.1.1 Groundwater Levels............................................................................................................ 5.1.2 Groundwater Level Trends.................................................................................................. 5.1.3 Vertical Groundwater Gradients......................................................................................... 5.1.4 Groundwater Contours....................................................................................................... 5.2 Change in Storage....................................................................................................................... 5.3 Seawater Intrusion...................................................................................................................... 5.4 Groundwater Quality Distribution and Trends........................................................................... 5.4.1 Anthropogenic Constituents: Diffuse Sources.................................................................... 5.4.2 Anthropogenic Constituents: Point Sources....................................................................... 5.4.3 Natural Constituents: Diffuse Sources................................................................................ 5.4.4 Natural Constituents: Point Sources................................................................................... 5.5 Subsidence.................................................................................................................................. 5.6 Interconnected Surface Water.................................................................................................... 5.6.1 Streams and Lakes.............................................................................................................. 5.6.2 Groundwater -Dependent Ecosystems................................................................................ 6 Water Budget (§ 354.18).................................................................................................................... 6.1 Climate........................................................................................................................................ 6.1.1 Historical Climate................................................................................................................ 6.1.2 Projected Climate................................................................................................................ 6.2 Water Budget Data Sources and Groundwater Model............................................................... 6.3 Historical Water Budget.............................................................................................................. 6.3.1 Historical Time Period......................................................................................................... 6.3.2 Inflows................................................................................................................................. 6.3.3 Outflows.............................................................................................................................. 6.3.4 Change in Storage............................................................................................................... 6.3.5 Sustainable Yield................................................................................................................. Page 81 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 6.3.6 Quantification of Overdraft................................................................................................ 6.4 Current Water Budget................................................................................................................. 6.4.1 Inflows................................................................................................................................. 6.4.2 Outflows.............................................................................................................................. 6.4.3 Change In Storage............................................................................................................... 6.4.4 Sustainable Yield................................................................................................................. 6.4.5 Quantification of Overdraft................................................................................................ 6.5 Projected Water Budget............................................................................................................. 6.5.1 Assumptions........................................................................................................................ 6.5.2 Inflows................................................................................................................................. 6.5.3 Outflows.............................................................................................................................. 6.5.4 Change In Storage............................................................................................................... 7 Sustainable Management Criteria (§ 354.22-30)............................................................................... 7.1 Sustainability Goal....................................................................................................................... 7.2 Process for Establishing Sustainable Management Criteria....................................................... 7.2.1 Minimum Thresholds.......................................................................................................... 7.2.2 Measurable Objectives....................................................................................................... 7.2.3 Undesirable Results............................................................................................................. 7.3 Chronic Lowering of Groundwater Levels Sustainability Indicator ............................................. 7.3.1 Locally Defined Undesirable Results................................................................................... 7.3.2 Minimum Thresholds and Measurable Objectives............................................................. 7.3.3 Relation to Other Sustainability Indicators......................................................................... 7.4 Change in Storage Sustainability Indicator................................................................................. 7.4.1 Locally Defined Undesirable Results................................................................................... 7.4.2 Minimum Thresholds.......................................................................................................... 7.4.3 Measurable Objectives....................................................................................................... 7.4.4 Relation to Other Sustainability Indicators......................................................................... 7.5 Seawater Intrusion Sustainability Indicator................................................................................ 7.5.1 Locally Defined Undesirable Results................................................................................... 7.5.2 Minimum Thresholds.......................................................................................................... 7.5.3 Measurable Objectives....................................................................................................... 7.5.4 Relation to Other Sustainability Indicators......................................................................... 7.6 Degraded Water Quality Sustainability Indicator....................................................................... 7.6.1 Locally Defined Undesirable Results................................................................................... 7.6.2 Minimum Thresholds.......................................................................................................... iv Page 82 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 7.6.3 Measurable Objectives....................................................................................................... 7.6.4 Relation to Other Sustainability Indicators......................................................................... 7.7 Subsidence Sustainability Indicator............................................................................................ 7.7.1 Locally Defined Undesirable Results................................................................................... 7.7.2 Minimum Thresholds.......................................................................................................... 7.7.3 Measurable Objectives....................................................................................................... 7.7.4 Relation to Other Sustainability Indicators......................................................................... 7.8 Depletion of Interconnected Surface Water Sustainability Indicator ......................................... 7.8.1 Locally Defined Undesirable Results................................................................................... 7.8.2 Minimum Thresholds.......................................................................................................... 7.8.3 Measurable Objectives....................................................................................................... 7.8.4 Relation to Other Sustainability Indicators......................................................................... 7.9 Management Areas..................................................................................................................... 7.9.1 Minimum Thresholds and Measurable Objectives............................................................. 7.9.2 Monitoring and Analysis..................................................................................................... 7.9.3 Explanation of How Operation of Management Area Will Avoid Undesirable Results...... 8 Monitoring Networks (§ 354.34)........................................................................................................ 8.1 Monitoring Objectives................................................................................................................ 8.2 Monitoring Network................................................................................................................... 8.2.1 Chronic Lowering of Groundwater Levels........................................................................... 8.2.2 Reduction of Groundwater Storage.................................................................................... 8.2.3 Seawater Intrusion.............................................................................................................. 8.2.4 Groundwater Quality.......................................................................................................... 8.2.5 Land Subsidence.................................................................................................................. 8.2.6 Depletion of Interconnected Surface Water....................................................................... 8.3 Groundwater Monitoring Protocol............................................................................................. 8.4 Data Management System.......................................................................................................... 8.5 Assessment and Improvement of Monitoring Network............................................................. 8.6 Annual Reports............................................................................................................................ 8.7 Periodic Evaluation by Agency.................................................................................................... 9 Projects and Management Actions (§ 354.44)................................................................................... 9.1 Projects....................................................................................................................................... 9.1.1 Project A.............................................................................................................................. 9.2 Management Actions.................................................................................................................. 9.2.1 Management Action A........................................................................................................ v Page 83 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 9.3 Projects Needed to Mitigate Overdraft...................................................................................... 10 Implementation Plan.......................................................................................................................... 10.1 Cost of Implementation.............................................................................................................. 10.2 Funding Alternatives................................................................................................................... 10.3 Implementation Schedule........................................................................................................... 10.4 GSP Annual Reporting................................................................................................................. 10.5 Periodic Evaluations of GSP........................................................................................................ 11 Notice and Communications (§ 354.10)............................................................................................. 11.1 Communications and Engagement Plan..................................................................................... 11.2 Nature of Consultations.............................................................................................................. 11.3 Public Meetings........................................................................................................................... 11.4 Incorporation of Feedback in Decision -Making Process............................................................. 11.5 Comments Received................................................................................................................... 11.6 Responses to Comments............................................................................................................. 12 Interagency Agreements (§ 357.2-4)................................................................................................. 12.1 Coordination Agreements........................................................................................................... 13 References.......................................................................................................................................... 14 Appendices......................................................................................................................................... vi Page 84 of 1183 SLO Basin Groundwater Sustainability Plan List of Figures County of SLO and City of SLO LIST OF FIGURES Figure 1-1: San Luis Obispo Valley Basin and Surround................................................................................1 Figure 3-1: San Luis Obispo Historical Annual Precipitation.........................................................................4 Figure 3-2: San Luis Obispo Valley Basin Existing Land Use Designations....................................................8 Figure 3-3: San Luis Obispo Valley Basin Water Supply Sources................................................................10 Figure 3-4: San Luis Obispo Valley Basin Water Use Sectors......................................................................12 Figure 3-5: San Luis Obispo Valley Basin Domestic Well Density...............................................................14 Figure 3-6: San Luis Obispo Valley Basin Production Well Density.............................................................15 Figure 3-7: San Luis Obispo Valley Basin Public Supply Well Density.........................................................16 Figure 3-8: San Luis Obispo Valley Basin Public Supply Well Density.........................................................17 Figure 3-9: Monitored Wells in the San Luis Obispo Valley Basin..............................................................19 Figure 3-10: San Luis Obispo Valley Basin Surface Water Features, Weather Stations, and Stream Gauges. .................................................................................................................................................................... Figure 3-11: San Luis Obispo Valley Basin Historical Annual Precipitation and CDFM...............................23 -- Figure3-12. City Land Use Map.................................................................................................................. 28 Figure 3-13. County Land Use Map (San Luis Obispo Planning Area)......................................................... 29 Figure 3-14. County Land Use Map (South County Planning Area)............................................................30 Figure 3-15. Los Ranchos/Edna Land Use Map...........................................................................................31 Figure4-1: Topographic map...................................................................................................................... 35 Figure4-2: Aerial Photograph..................................................................................................................... 36 Figure 4-3: Annual Precipitation................................................................................................................. 37 Figure 4-4: Bottom Elevation of Basin........................................................................................................ 38 Figure 4-5: Thickness of Basin Sediments................................................................................................... 39 Figure 4-6: Soil Hydrologic Groups..............................................................................................................41 Figure 4-7: Stratigraphic Column................................................................................................................43 Figure4-8: Geologic Map............................................................................................................................44 Figure 4-9: Lithologic Data Points and Cross Section Lines.........................................................................51 Figure 4-10: Cross Section Al-A2................................................................................................................ 52 Figure 4-11: Cross Section A2-A3................................................................................................................ 53 Figure 4-12: Cross Section A3-A4................................................................................................................ 54 Figure4-13: Cross Section B-B'................................................................................................................... 55 Figure 4-14: Cross Section Cl-Cl '............................................................................................................... 56 Figure 4-15: Cross Section C2-C2'............................................................................................................... 57 Figure4-16: Cross Section D-D.................................................................................................................... 58 Figure4-17: Cross Section E-E..................................................................................................................... 59 Figure4-18: Cross Section F-F..................................................................................................................... 60 Figure4-19: Cross Section G-G'.................................................................................................................. 61 Figure4-20: Cross Section H-H.................................................................................................................... 62 Figure4-21: Cross Section 1-1'..................................................................................................................... 63 Figure 4-22: Hydraulic Parameter Data Locations...................................................................................... 66 Figure 4-23: Subsidence Potential.............................................................................................................. 74 vii Page 85 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Tables Table 3-1: Land use categories defined for the SLO Basin by DWR(2014).................................................. 7 Table 3-2: Summary of surface water supply sources available to the SLO Basin........................................9 Table 3-3: DWR and County Wells..............................................................................................................13 Table 3-4: Stream gauges and summary of records available.................................................................... 20 Table 3-5: Weather station Information and summary of records available ............................................. 21 Table 3-6. Average Monthly Climate Summary 1987 — 2018 at Cal Poly Weather Station 52...................24 Table 3-7. Los Ranchos/Edna Land Use Acreage........................................................................................ 31 Table 4-1: SLO Basin Well Aquifer Test Data Summary.............................................................................. 68 Table 4-2: SLO Basin Well Specific Capacity Data Summary....................................................................... 69 viii Page 86 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES Appendices ix Page 87 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level x Page 88 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant xi Page 89 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 90 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 3 DESCRIPTION OF PLAN AREA (§ 354.8) 3.1 SLO BASIN INTRODUCTION Description of Plan Area (§ 354.8) The SLO Basin is oriented in a northwest -southeast direction and is composed of unconsolidated or loosely consolidated sedimentary deposits. It is approximately 14 miles long and 1.5 miles wide. It covers a surface area of about 12,700 acres (19.9 square miles). The SLO Basin is bounded on the northeast by the relatively impermeable bedrock formations of the Santa Lucia Range, and on the southwest by the formations of the San Luis Range and the Edna fault system. The bottom of the SLO Basin is defined by the contact of permeable sediments with the impermeable bedrock Miocene -aged and Franciscan Assemblage rocks. The SLO Basin is commonly referenced as being composed of two distinct valleys, with the San Luis Valley in the northwest and the Edna Valley in the southeast. The San Luis Valley comprises approximately the northwestern half of the SLO Basin. It is the area of the SLO Basin drained by San Luis Obispo Creek and its tributaries (Prefumo Creek and Stenner Creek west of Highway 101, Davenport Creek and smaller tributaries east of Highway 101). Surface drainage in San Luis Valley drains out of the SLO Basin, flowing to the south along the course of San Luis Obispo Creek, toward the coast in the Avila Beach area, approximately along the course of Highway 101. The San Luis Valley includes part of the City and California Polytechnic State University (Cal Poly) jurisdictional boundaries, while the remainder of the San Luis Valley is unincorporated land. Land use in the City is primarily single - and multi -family residential, commercial, industrial, and a small amount of land in agricultural uses. The area in the northwest part of the SLO Basin, along Los Osos Valley Road, has significant areas of irrigated agriculture, primarily row crops. The Edna Valley comprises approximately the southeastern half of the SLO Basin. The primary creeks that drain the SLO Basin are the east and west branches of Corral de Piedras Creek, which join to form Pismo Creek, draining south out of the Edna Valley into Price Canyon. Smaller unnamed tributaries drain south from the SLO Basin in the extreme southeastern part of Edna Valley, ultimately joining Pismo Creek. Some of the unincorporated lands in Edna Valley are served by various private water purveyors. The primary land use in the Edna Valley is agriculture. During the past two decades wine grapes have become the most significant crop type in the Edna Valley. The physical definition of the SLO Basin boundary is the contact between the unconsolidated or loosely consolidated sediments and the basement rock of the Miocene -aged formations and Franciscan Assemblage. There is a topographic high point in the underlying bedrock elevation between the San Luis and Edna sub -basins. The watershed divide and the bedrock divide are not coincident. The sediments of the Edna Valley have significantly greater thickness than those of the San Luis Valley. Precipitation that falls west of that divide ultimately flows to Davenport and San Luis Obispo Creeks, and precipitation that falls east of that divide flows to Corral de Piedras Creek or the other small tributaries, ultimately flowing to Pismo Creek south of the SLO Basin. The primary weather patterns for the SLO Basin derive from seasonal patterns of atmospheric conditions that originate over the Pacific Ocean and move inland. As storm fronts move in from the coast, rainfall in the area falls more heavily in the mountains, and the SLO Basin itself receives less rainfall because of a muted rain shadow effect. Average annual precipitation ranges from approximately 18 inches throughout most of the SLO Basin to about 22 inches in relatively higher elevation areas near the City and Cal Poly. Figure 3-1 presents the time series of annual precipitation for the period of record from 1870 to 2018 at the Cal Poly weather station No. 52. The average historical rainfall at this location to date is 21.69 inches, with a Page 91 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) standard deviation of 8.75 inches. The historical maximum is 49.99 inches, which occurred in 1884. The historical minimum is 4.56 inches, which occurred in 2013. Page 92 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO .El 55 50 45 ►.LI 35 u 0 30 .Q 'u L 25 a 20 15 10 5 0 Description of Plan Area (§ 354.8) 1870 1875 1880 1885 1890 1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Year Prepared for: '1444 Author. EC Q 11/26/2019 SAN LUIS OBISPO VALLEY BASIN GSP Legend Precipitation (Annual) Historical Average Precipitation Notes: 1. Data Source: Cal Poly State University, Cal PolyiNOAA Station San Luis Obispo Historical Annual Precipitation Figure 3-1 11 Page 93 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO 3.2 ADJUDICATED AREAS The SLO Basin is not an adjudicated basin. 3.3 JURISDICTIONAL AREAS In addition to MOA Parties, there are several entities that have some degree of water management authority in the SLO Basin. Each entity is discussed below. 3.3.1 Federal Jurisdictions There are no federal agencies with land holdings in the SLO Basin. 3.3.2 Tribal Jurisdiction The two prominent Native American tribes in the County are the Obispeno Chumash and Salinan Indian Tribes. The Chumash occupied the coast between San Luis Obispo and northwestern Los Angeles County, inland to the San Joaquin Valley. They were divided into two broad groups, of which the Obispeno were the northern group. The Salinan were northern neighbors of the Chumash, and although the presence of a firm boundary between the Chumash and the Salinan is uncertain, ethnographic accounts have placed Salinan territories in the northern portion of the County. However, these two tribes do not have any recognized tribal land in the SLO Basin. 3.3.3 State Jurisdictions The State of California University system owns and operates land that is associated with California Polytechnic State University, San Luis Obispo (Cal Poly) located in the northern edge of the SLO Basin off Hwy 1. Cal Poly is a significant user of local water sources and manages their water supply in conjunction with the City. The City treats the wastewater generated from Cal Poly. There are no California State Parks or other State-owned lands or entities located within the SLO Basin. 3.3.4 County Jurisdictions The County of San Luis Obispo and the associated San Luis Obispo County Flood Control and Water Conservation District (SLOFCWCD) (see section under Special Districts below) have jurisdiction over the entire County including the SLO Basin. The County owns approximately 300 acres of land in the SLO Basin and is primarily located in the vicinity of the SLO County Airport which makes up the majority of the land owned by the County. 3.3.5 City and Local Jurisdictions The City is centrally located in the SLO Basin and has land and water management authority over its incorporated area. The City has four primary water supply sources including Whale Rock Reservoir, Salinas Reservoir, Nacimiento Reservoir, and recycled water (for irrigation), with groundwater serving as a fifth supplemental source. Three major mutual water companies exist in the SLO Basin: Edna Valley Growers, Varian Ranch, and Edna Ranch Mutual Water Companies. One investor owned utility exists within the SLO Basin: Golden State Water Company (GSWC). GSWC provides groundwater that is pumped from the Edna Valley Basin to residential and agriculture customers. 3.3.6 Special Districts The San Luis Obispo Flood Control and Water Conservation District (SLOFCWCD) is a dependent Special District governed by the County Board of Supervisors. It has jurisdiction over all of the County including the SLO Basin and was established as a resource to help individuals and communities in San Luis Obispo County identify and address flooding problems with the purpose "to provide for control, disposition and distribution of the flood and storm waters of the district and of streams flowing into the district...". 5 Page 94 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 3.4 LAND USE Description of Plan Area (§ 354.8) The County, City and State have land use authority in the SLO basin within their respective jurisdictions. Land use information for the SLO Basin was based on DWR's land use database (DWR, 2014). The 2014 land use in the SLO Basin is shown on Figure 3-2 and is summarized by group in . All land use categories except native vegetation listed in Table 3-1 are provided by DWR (DWR, 2014). The areas of the basin that did not have a land use designation were assumed to be native vegetation. Table 3-1: Agricultural Land use categories defined for the SLO Basin by DWR (2014). Land Use Category Acres Citrus and subtropical 136 Deciduous fruits and nuts 21 Grain and hay crops 183 Idle 713 Pasture 179 Truck nursery and berry crops 1079 Urban 6,412 Vineyard 1,929 Young perennial 2 Native vegetation <1 Total 10,656 Page 95 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO i Eto Lake l,. Warden La)re F Description of Plan Area (§ 354.8) it Chorro 4� W r — �Reservoir � I ` ' c . �. l � _ j''' i ,ram � �• ' ' / � � • r ��1� r 1 _ F � i I"..— r'7 % f ;te r �' "- I ow. K4L I jr } Prepared for: IN 0 Author EC Dale: 11f221201g SAN LUIS ORISPO VALLEYBASIN GSP San Luis Obispo Bay 41 C ., d - AL 41. Iw ee �6 : `S R t v (o �' � _ e I ..-- I . ' 4 r . ! Qc N References: 1 in : 1.5 mi 1. Coordinate System. NAo 1963 StateFlane California V FIRS O405 Feet A Proi-tion Lambert Conformal Conic ■N' 0 OS 1 2 Oatum_ North American 1983 Mi 2. 6 0.75 1-5 3 3_ Km Explanation DWR Land Use Designations - Citrus and Subtropical Deciduous Fruits and Nuts Grain and Hay Crops Idle Pasture Truck Nursery and Berry Urban Vineyard Young Perennial City Limits City Limits Basin and GSA Boundaries San Luis Obispo Valley Basin Boundary City of San Luis Obispo GSA County of San Luis Obispo GSA Surface Water Sources Lakes and Reserviors —._— Surface Water Lopez j -- ,r A, sri, DigitalGlobe, GecFye, Earthstar Geographics. CNES/Airbus DS, USDA, USIGS, AeroGRID," GI and the GIs Uscrcii- murity Notes: San Luis Obispo Valley Basin Land Use 1. Land Use D-iignalions from L)V'/R (2014), data obtained from qi—torcagov Designations 2 3. Figure 3-2 FA Page 96 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) 3.4.1 Water Source Types Entities in the SLO Basin utilize three types of water sources to meet the demands: groundwater, surface water, and recycled water. Excluding the City, Cal Poly, and Edna Valley Golf Course, all water demand in the SLO Basin are met with groundwater. Cal Poly has rights to 33.71% of water from Whale Rock Reservoir and the rest of their water supply comes from local groundwater. The City has an entitlement to water from the Nacimiento Water Project, rights to Salinas Reservoir (Santa Margarita Lake), rights to 55.05% of water in Whale Rock Reservoir, SLO Basin groundwater, and recycled water from the City's Water Resource Recovery Facility (WRRF). The City has imported supplies from Salinas Reservoir, located near the community of Santa Margarita, since 1944, Whale Rock Reservoir, located near the community of Cayucos, since 1961, and Lake Nacimiento since 2011. Table 3-2 summarizes the surface water supply available from each source and Table 3-3 shows the location of water supply source types within the SLO Basin. Table 3-2: Summary of surface water supply sources available to the SLO Basin. Supply Sources Amount Available (AFY) Nacimiento Reservoir- City 5,4821 Salinas Reservoir - City 4,9101 Whale Rock Reservoir - City Recycled Water - City —1,0001 Total 11,392 1 City of San Luis Obispo, General Plan, Water and Wastewater Management Element, 2018.. Q Page 97 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) ' f�~ - xerf Lake Explanation Lake . I,.�. \ vacrrn.emo 4 Water Supply Sources, Pipelines, r and Facilities Water Source Water Resource Recovery Facility Water Treatment Plant h ' " _ J Existing Recycled Water I f Mains Whale Rock Pipeline Y Lake Nacimiento Pipeline - — 101 1. > Salinas Reservoir Pipeline '22) L Basin Boundary San Luis Obispo Valley - Basin Boundary f Surface Water Sources " Lakes and Reserviors Siiver _ Lake s zz aUenoory Cr Source Es eAltalGlobe,rGeoEye, Ea Geographics, CNESIAirbus DS, USDA, AeroGRID, IGN, and the GIS User Con r Prepared for: N1 References: 19W Author EC n in 4-5 mi 1. Coordinate System, NAD 1983 StatePlane California V FIPS 0405 Feet f r fiNo Lambert Con19UU Conic11 11718I2019 Q 0 15 3 6 MI O,q-ti North American L),,t 2- N, 0 225 4.5 9 3- SAN LUIS OBISPO VALLEY BASIN GSP Km Notes: 1. 2. 3. San Luis Obispo Valley Basin Water Supply Sources Figure 3-3 Q Page 98 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) 3.4.2 Water Use Sectors Water demand in the SLO Basin is organized into the six water use sectors identified in the GSP Emergency Regulations. These include: • Urban- Urban water use is assigned to non-agricultural water uses in the City and census - designated places. Domestic use outside of census -designated places is not considered urban use. • Industrial -There is limited industrial use in the SLO Basin. The DWR land use designations in the SLO Basin does not include industrial uses. • Agricultural- This is the largest groundwater use sector in the SLO Basin by water demand. • Managed wetlands- There are several managed wetlands in the SLO Basin that are managed by both federal, state, and local agencies. In general, wetlands in the area are managed by either of the following agencies: (1) City of San Luis Obispo, (2) California Department of Fish and Wildlife, (3) California State Water Resources Control Board, (4) U.S. Fish and Wildlife Service, and (5) U.S. Army Corps of Engineers. The wetlands and natural vegetation areas that are potentially dependent ecosystems include Laguna Lake and reaches of the San Luis Obispo Creek, Prefumo Creek, Stenner Creek, Davenport Creek, East and West Corral De Piedra Creeks, and Pismo Creek. Water use for these ecologically sensitive areas will be addressed in the water budget and modeling scope of this GSP in order to designate appropriate management actions and proposed projects to provide adequate water supply for natural water use of these areas. • Managed recharge- There is no managed recharge in the SLO Basin. Recycled water discharge to creeks and applied irrigation is included in the urban water use sector. • Native vegetation- This is the largest water use sector in the SLO Basin by land area. This sector includes rural residential areas. Figure 3-4 shows the distribution of the water use sectors and potential groundwater dependent ecosystems in the SLO Basin. 10 Page 99 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO f J Eto L6ke r Warden Lake IFr • f Ar l., Prepared for: 94W 10 Author EO Daa: 11i2M019 SAN LUIS OBISPO VALLEY BASIN GSP Reservoir f 1 •. f r �-raom Cr�,e� -ago T r l+rr #► At Ir Explanation DWR Water Use Designations � t Ai Agriculture �f 1 'or .00 .'• •r �! A I ON *j ma � d t - •'ram t =�� .r- _ v� !� ,rid San Luis Obispo Bay N References: 1 in : 4.5 rn 1. Coordinate System: NAD 1933 S[atePlane California V FIPS O405 Feet APr jection_ Lambert Conformal Conic Datum. North American 1983 Mi 2. 0 075 1s 3 K. Description of Plan Area (§ 354.8) Urban Natural Vegetation and Rural Residential Potential Groundwater Dependent Ecosystems (GDEs) Natural Vegetation GDE - Wetland GDE City Limits City Limits Basin and GSA Boundaries San Luis Obispo Valley Basin Boundary City of San Luis Obispo \\\ GSA County of San Luis Obispo GSA Surface Water Sources Lakes and Reserviors Surface Water r A •�Ft _ .r rj1j_� t 't Lopez Lake � Lopez- Re5ervoir; r3 1h. �r r di r .40�. UigitalGlobe, Geo Eye, Earthslar Geographics, CNESlAirbus QS, USIA, USGS. AeroGRIU. IGN,,and the GIS User Comn Notes: San Luis Obispo Valley Basin Water Use Sectors 1. Land Use Designations from DWR f20Mj, data obtained from gi—ter-sago° and Potential Groundwater Dependent 2. GDE data obtained from gi—ater ca.g. 3. Ecosystems (GDEs) Figure 3-4 11 Page 100 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 3.5 DENSITY OF WELLS Description of Plan Area (§ 354.8) Well types, well depth data, and well distribution data were downloaded from DWR's well completion report map application (DWR, 2018). DWR categorizes wells in this mapping application as either domestic, production, or public supply. These categories are based on the well use information submitted with the well logs to DWR. Well information was also collected from County of San Luis Obispo Environmental Health Services (EHS). The EHS dataset was compiled from information gained from the well construction permit application process. Table 3-3 summarizes the types of wells by use for all well logs submitted to DWR and EHS. Table 3-3: DWR and County Wells Well Data Source Type of Well Total No. of Wells DWR Domestic 75 Production 71 Public Supply 24 Total 170 County EHS Domestic Private 355 Domestic Public 43 Irrigation 231 Total 629 Figure 3-5, Figure 3-6, and Figure 3-7 show the density of wells in the SLO Basin by their types of use. The DWR data used to develop these maps is not necessarily the same set of well data held EHS as shown in Figure 3-8. DWR data was used to develop maps of well densities because they are organized for easy mapping of well density per square mile. These maps should be considered representative of well distributions, but are not definitive. It is also important to note that both the DWR and EHS well databases are not updated with information regarding well status and the well locations are not verified in the field. Therefore, it is uncertain whether the wells in these databases are currently active or have been abandoned or destroyed. 12 Page 101 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO �1 Etc Lake t` Warden La!,_ Description of Plan Area (§ 354.8) E � ram; �._P�Fumo C�ee dill� /ram 1 Fro.�roe Chorro Reservoir yNi . a j '/ \ I a K , ` l ee � 3 \1 i .;. Explanation I Domestic Wells per Square Mile >10 r #W.� m 1 �+ 44 1 cow ,• `AO 6-10 1-5 Basin Boundary San Luis Obispo Valley Basin Boundary Surface Water Sources Lakes and Reserviors — Surface Water ♦] }lit 00 dF "#�� , a I 'r( r Oave'nporl 8 1`/ t ,\ 1 ,gj,4 : 1� I .�,#� [F f }�, i— r Creek r ��-�. / . row op .r NW r 00 sill", 27 J' r/ 1 / r lip l San Luis Obispo Bay ii Prepared for: I%k Author: EC QDate_ 11124@Ot9 SAN LUIS OBISPO VALLEY BASIN GSP NReferences: 1 in, 1.5 mi 1- Coordinate System: NAD 1903 Stat.Pl... California V RIPS O405 Feet A Datum Lien Lambert Conformal Conic 0 05 1 2 DeWm: North American 1983 Mi 2- 0 0.75 1.5 3 3- Km it Source r�W ," ss Oil It. �4, dill, — bp- _: ICt LJrez Lake t - '$ r Reservoirl, .d I, DigitalGlobe, GeoEye, Earthslar Geographies, CNESIAirbus DS, USDA, USGS, AeroGRID,"GN nd the GIS UserCommurity Notes; San Luis Obispo Valley Basin Domestic Well 1, Well data provided by DWR (201S); data obtained from gis.waler.ca.gov Density 2, 3. Figure 3-5 13 Page 102 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO �1 Etc Lake t` Warden Lalr- Description of Plan Area (§ 354.8) �. %.-... Chorro ,;It.;! _ Reservoir �N .� '/ �' Explanation E" ;� ti Ji r Production Wells per Square Mile 10 i Y y� 4' • i 4 . '-l. � Basin Boundary i o�ree� f" ice- San Luis Obispo Valley i Basin Boundary ' ' J ' 1 �f I r Surface Water Sources Lakes and Reserviors sr cam" r l' . Pref — Surface Water 4 ram' 1% 4r" _ 10 .tF• is -.i �--'� - �... Tom' i All- %ll 21 g �' jJ �� i f , .}' J Veil 4 !_ I �. creek Z NA - r Tim •_ 2 r ��•.' �l ill �`� ti j[ 2 ide P' ' r * ; ` 1 i rJ / - • :: dw 'NIL .ter %%�~ ! Lo,_ z Lake { 'i.� � - .' R�..� _ �.. ��0 . � f - f- — vim" - F'�4 •� - ~ 'J11W O : Reservoir j San Luis Obispo Bay f /' r f t ` ra �t . J, "? A' fi`. tt y AT. Source'.Esri, DigitalGlohe, GeoEye, Earthslar Geographies, CNESIAirbus DS, USDA, USGS, AI=roGRID, IGNN$nd the GIS User Commuriity Prepared for: ^' References: V 1 in, 1.5 mi 1- Coordinate Lambert C: NAD 1983 StatePlane California V RIPS 0405 Feet Author: EC A Datum: No Lambert Conformal Conic 12019 0 05 1 2 Datum: North American 1983 Mi 2 0 0.75 1.5 3 3- SAN LUIS OBISPO VALLEY BASIN GSP Km Notes; San Luis Obispo Valley Basin Production Well 1, Well data pra�ided by DVW (2018); data obtained from gis kur.ca.gc, Density 2, 3. Figure 3-6 14 Page 103 of 1183 Description of Plan Area (§ 354.8) �. %.-... Chorro Reservoir .� ���,�! �� _ , � • T r� , Explanation I toreek ; r Sri*.. ;� - -,.\ J/ Public Supply Wel 1-5 Basin Boundary San Lui: Basin Bc Surface Water So \ f Lakes at +�-r •rs / , — Surface 4r , , f - A f .0- 1 Sr C' f / f `i tom`! a rI r 1 Fir i Lagur,.- \ � �A. ! r � a r •f room Cr, 4 �P� i a0.}rDo SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO �1 i Etc Lake I Warden Lake r�W I 'fee .��(.� � •• ;. 1 � X" - ) I 1� t # ". • f� r � eta 'r � , t � r !J �:-_�•,• ��is'� t+�� �� .s ��� f L+ i� art ezZake I ff ter Reservoir _•{ +{ - �-�,��-� a •� � , ,r. - _ .� �- ` `1. ;�'`. -�j� • ,}�] •, ��`{� �� �t. San Luis Obispo BayIt 4F y= l� - Source, Esri, DigitalGlobe, GeoEye, Earthslar Geographies, CNESIAirbus DS, USDA, USGS, AeroGRID`IGN and the GIS User Comimumty Prepared for: Dater 12 Date 11124@Ot9 I%k Q SAN LUIS OBISPO VALLEY BASIN GSP ^' V 1 in : 1.5 mi A N 0 05 1 2 Mi 0 0.75 1.5 3 K. References: 1 Coordinate System NAD 19B3 StatePlane Calif—ia V RIPS 0405 Feet Lambert Conformal Conic OeW m: North American 1983 Datum: 3 - Notes: 1 Well data provided by DWR i2018J: data obtained Gom gis.waler.ca.gov 2, 3. San Luis Obispo Valley Basin Public Supply Well Density Figure 3-7 15 Page 104 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) R1-16rvcir leek er f Etc Lake Warden Lake 7 C2 A.. 4 i 0 4 0 -awl r 'fit.od3 0 2 0 Pr . 6/21/'o Laguna L ke 00 9 0 4 14 Explanation SLID County EHS Wells per Square Mile 51-100 41 -50 31-40 0 f 21 -30 10 w0d - J1 11-20 tie 1-10 ' west C 10, r'0 "7' SLO County EHS Well Types Domestic Private Domestic Public Irrigation 9 4 Basin Boundary 400 24 0 wf• San Luis Obispo Valley � P 2 Dave, r 01, '7 0,4 /.0 'Po. In San Luis Obispo Bay 023 J Basin Boundar Ay Surface Water Sources d' 0 ®2 cLakes and Reserviors pk/ v 2 05t 14 Surface Water 0 % ♦ 0o;. L 227 0-00 Jel . J 1 . 0 34 0 . "-7 0, 00 Z 00 0 19jfe z Lake 0 031111 Lopez x woe _J4,w Source-,Esri, DigitalGlobe, GeoEye, Eartlhstar Geographies, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN;and the GIS User-Cdmmu6ity Prepared for: References: 4111144 N I in 1.5 mi "Coordinate System NAD 1983 StatePlane California V RIPS 0405 Feet Author A Projection: Lambert Conformal Ccnic Date 111250019 0 05 1 2 Datum: Ncrth American 1983 Mi 2 0 075 Is 3 3 SAN LUIS OBISPO VALLEY BASIN GSP K. Notes: San Luis Obispo Valley Basin County Environmental Health Services Well Density 3. Figure 3-8 16 Page 105 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) 3.6 EXISTING MONITORING AND MANAGEMENT PROGRAMS 3.6.1 Groundwater Monitoring Groundwater levels and quality are currently measured in the SLO Basin by the SLOFCWCD and a variety of other agencies as described below. Figure 3-9 shows the locations of monitored wells identified in the Groundwater Ambient Monitoring and Assessment (GAMA) program (i.e. publicly available data) that are monitored by several public agencies, the SLOFCWCD, and the Central Coast Regional Water Quality Control Board (CCRWQCB) Irrigated Lands Program. The monitoring network also includes other wells in the area designated as private that are not shown on this map (Figure 3-8). Additional evaluation of the current monitoring program will be conducted for the GSP to establish a representative monitoring network of public and private wells that will be used during plan implementation to track groundwater elevations and ensure that minimum thresholds have not been exceeded. 3.6.1.1 Groundwater Level Monitoring The SLOFCWCD has been monitoring groundwater levels county -wide on a semi-annual basis for more than 50 years to support general planning and for engineering purposes. Groundwater level measurements are taken once in the spring and once in the fall. The monitoring takes place from a voluntary network of wells. In the SLO Basin, there are 16 active wells in this program (Figure 3-9). The voluntary monitoring network has changed over time as access to wells has been lost or new wells have been added to the network. 3.6.1.2 Groundwater Quality Monitoring Groundwater quality is monitored/reported under several different programs and by different agencies including: • Municipal and community water purveyors must collect water quality samples on a routine basis for compliance monitoring and reporting to the California State Water Resources Control Board (SWRCB) Division of Drinking Water (DDW). • The USGS collects water quality data on a routine basis under the GAMA program. These data are stored in the State's Geotracker GAMA system. • There are multiple sites that are monitoring groundwater quality as part of investigation or compliance monitoring programs through the CCRWQCB. See Figure 3-9 for CCRWQCB well monitoring locations through the GEotracker GAMA system. • The CCRWQCB under Agricultural Order No. R3-2017-0002, a Conditional Waiver of Waste Discharge Requirements for Discharges from Irrigated Lands, requires all growers to implement groundwater monitoring, either individually or as part of a cooperative regional monitoring program. Growers electing to implement individual monitoring (i.e., not participating in the regional monitoring program implemented by the Central Coast Groundwater Coalition [CCGC] within the SLO Basin) are required to test all on -farm domestic wells and the primary irrigation supply wells for nitrate or nitrate plus nitrite, and general minerals (including, but not limited to, TDS, sodium, chloride, and sulfate). • California Water Data Library contains groundwater level and water quality monitoring stations. The data available from this resource has been used above. 17 Page 106 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Lto Lake Warden Lake Description of Plan Area (§ 354.8) . -4 chorro Reservoir Greek ..;i1 Explanation Monitored Wells in the SLO Basin Irrigated Lands Program Wells GAMA Wells * SLO County Groundwater Level Monitoring Program Basin Boundary San Luis Obispo Valley Basin Boundary Surface Water Sources Lakes and Reserviors r rE'refurno l �` `r / � • � � • � � ' � 1 ' Creek �� a - ' •.1 #' r ; d Da ek �p 4 40 f '•�1 r - rj _ i If �, r z_27 La yC '� •1 ! �•* Sad 1 e,• f_ i r ri I r A,' r r„ �. + %fin,, —\. Surface Water z I fir it 'yam- G{eat +, a f• 7 _t ! r7� f 1al de Q `� ��,r � ► • f1 • 4�� N .! f� ' '' `�' 'art.• t'••# � *yL"ogpez LakAl f { o 'ice 1 �•zrf rr ��� q,Z �. t=: - Lopez �� /� �• Reservoir - �- �.,; 0��4- San Luis Obispo Bay rj nt+.,.• f . L 'T, �y r�,~ ( i!� •? -„ � •�' _ 1 I'r�.. � K• 104�tShe Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, ONES/Airbus DS, USDA, USGS,AeroGRIDGIs User Commuriity Prepared for: ^I References: V 7 in : 7.5 mi 1. Coordinatem teC NAD al Z StalePlane California V FIP504 5 Feet Author. EC `n Projection Lambert Conformal Conlc i ! ■j 0 0,5 1 2 Datum. North American 1983 Date: 1212f2099 N Mi 2. 0 075 1.5 3 S. SAN LUIS OBISPO VALLEY BASIN GSP Km 4+ Notes: 1- Well location data obtained from geotracke—terheardsca. gov 2. 3- Monitored Wells in the San Luis Obispo Valley Basin Figure 3-9 W] Page 107 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO 3.6.1.3 Surface Water Monitoring The Water Resources Division of the SLO County Public Works maintains six (6) real-time data monitoring stream gauges within the San Luis Obispo Creek watershed and all except Andrews St. Bridge is located within the SLO Basin. As summarized in Table 3-4, each stream gauge measures stage at 15-minute intervals. Stage -discharge relationships, or rating curves, for each of the five stream gauge stations were generated by Questa Engineering Corps in 2007 as part of the San Luis Obispo Creek Watershed Hydrology and Hydraulic Model Calibration Study. More recently (2018/2019), Central Coast Salmon Enhancement has approximated rating curves for the Andrews St., Elks Lane, and Stenner Creek gauge stations based on recorded stage data and measured flows. The location of the five County gauges are presented in Figure 3-10. In addition to the County gauges, the City of San Luis Obispo routinely estimates flow at four locations (RW- 4, RW-5, RW-7, RW-8) along San Luis Obispo Creek in the vicinity of the City's WRRF outfall as part of its National Pollutant Discharge Elimination System permitting program. RW-8 at South Higuera Bridge is located outside of the SLO Basin. Flow at the four locations (RW-4, RW-5, RW-7, and RW-8) is calculated weekly from April through the end of October based on the depth measurements recorded along the creek cross-section and are located within the Basin. Table 3-4: Stream gauges and summary of records available. SLO County Stage 15 Minutes 2006 NAVD 88 SLO County Stage 15 Minutes 2005 NAVD 88 SLO County Stage 15 Minutes 2005 NAVD 88 SLO County Stage 15 Minutes 2005 NAVD 88 SLO County Stage 15 Minutes 2005 NAVD 88 SLO County Stage 15 Minutes 2019 NAVD 88 City of SLO Depth, Flow Weekly 2005 - City of SLO Depth, Flow Weekly 2005 - City of SLO Depth, Flow Weekly 2005 - City of SLO Depth, Flow Weekly 2005 - 3.6.1.4 Climate Monitoring Climate monitoring in the SLO Basin includes stations that collect data related to temperature, evapotranspiration, relative humidity, atmospheric pressure, precipitation, and other climate parameters. Four stations monitored by San Luis Obispo County Public Works collect one or more climate parameters in the SLO Basin. The locations of these stations are shown on Figure 3-10. The National Climatic Data Center has three stations within the County of San Luis Obispo and one station within the SLO Basin that collect climate data. These stations do not have extensive historic data. The station with the most precipitation data not associated with the National Climatic Data Center, Cal Poly Weather Station 52 (CPWS-52), began recording data in 1870. The Cal Poly Weather Station 52 measures daily temperatures and other climate parameters in addition to precipitation. Daily records are available from April 1986 to present. Table 3-5 lists the climate stations and summary of records available. 19 Page 108 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO The long-term precipitation and cumulative departure from the mean (CDFM) measurements at CPWS-52 are shown in Figure 3-11 from 1870 - 2018. Average annual precipitation at this station varies from approximately 7 to 55 inches with a mean annual average precipitation of 21.95 inches. The longest dry period on record occurred from 1943 —1965 and the longest wet period on record occurred from 1899 — 1916. Table 3-6 provides a summary of average monthly rainfall, temperature, and evapotranspiration (ETo) for the SLO Basin from CPWS-52. Table 3-5: Weather station Information and summary of records available. CIMIS Precipitation, Temperature, Daily 1986 Evapotranspiration SLO County Precipitation 12-Hour 2005 SLO County Precipitation 12-Hour 2005 SLO County Precipitation 12-Hour 2005 Weather Element Precipitation, Temperature Daily 2015 20 Page 109 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Lto Lake Warden Lake Description of Plan Area (§ 354.8) Prefumo room Creek r r _ r �cP Creek x - l u`Is San Luis Obispo Bay Prepared for: Mk Author: EC 0Hate_ 1 V2412019 SAN LUIS OBISPO VALLEY BASIN GSP 40 Chorro � y i ,' r,r. Explanation Weather Stations and Stream Gauges Stream Gauges - ' . . �!r � 1 • O Weather Stations r�eoervwr�-- - �z i aL eC`G;: SLO Basin and Watershed Boundaries �%, San Luis Obispo Valley Sa�'Luis Obispo , �... Basin Boundary Creek Watershed t - � Ca! Poly Pismo Creek Watershed i'� � � "!' � � "���..JJJ J� �r �.. Station #52 r+ •'��' San Luis Obispo Creek r1 Watershed � SLO Reservoir ` � ••' Surface Water Sources GreekYY at f, i Nipoinoi= / /y'a✓wJ•/ ?Mali O Street r Bridge Laguna L ke {Road Elks Lane �f w 7 i RW-5 E Fork at lasnors -'" r' AO'1 Lakes and Reserviors Andrews Surface Water Street Bridge'^;„ ,, r Pismo Creek 4 !% , Watershed , _ �. �� _•` ' The Gas E �J Company '7q. a '{ 4 NReferences: 1 in : 1.5 mi 1- Coordinate System: NA C 1983 Stat ... California V RIPS O405 Feet A Projection Lambert Conformal Conic 0 0.5 1 2 Datum: North American 1983 Mi 2- 0 0.75 1.5 3 3- Krn f r � Lopez Reservoir Source: Esri, DigitalGlobe, GeoEye, Earthslar Geographiss, CNESIAirbus DS, USDA, USGS, Aero .-**.� f Lake Y id the GIS User Community Notes; San Luis Obispo Valley Basin Surface Water 1, stream gauge and weather station locutions provided by the County and Features, Weather Stations, and Stream Gauges Nafioanl Climatic Data Center 2. Pismo Creek watershed and the combined upper and lower San Luis Obispo Creekwatersheds are based on USGS Hydrologic Units (HUC-12) 3 Figure 3-10 21 Page 110 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO 60 Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry 80 1884 1890 1905 1916 1934 1943 1968 1983 1990 2 1 55 70 - 60 50 - 50 45 - - - - - - - - - - 40 40 - 30 35 - 20 ci n 0 30 I - 10 ra CL 25 — - - - - - - - -- - - _ - - - - - 0 69 - - - - - -10 20 -20 15 - --- - -- - — - - - - - — — - -- -30 10 - - - - -40 5 -50- 0 ........... ........ �........ i.....i.. i. i.....i.. i.. ........ .i...... . i ....i.. i.....i �... i i . .. .... �.....i... i.....i. i.... i... -60 1870 1875 1880 1885 1890 1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Year Prepared for: Legend Not San Luis Obispo Historical Annual Ift Author: F� Precipitation (Annual) - CDFM 1. Data source: Cal Poly state university, Cal Poly/NOAA station Precipitation and CDFM IN11(26/26I9 Historical Average Precipitation SAN LUIS OBISPO VALLEY BASIN GSP Figure 3-11 22 Page 111 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) Table 3-6. Average Monthly Climate Summary 1987 — 2018 at Cal Poly Weather Station 52. January Average Precipitatio nches)' 0.14 0.15 0.11 0.03 Average ETo Average Temperature (inches)' (OF)' 0.07 54 0.09 54 0.12 56 February March April 0.16 57 May 0.02 0.18 59 June 0.01 0.2 62 July 0 0.2 64 August 0.13 0.19 64 September 0.2 0.16 64 October 0.04 0.13 63 November 0.05 December 0.11 Monthly Average 0.08 [Average Calendar 21.69b0.14r 0.09 58 0.07 53 0.14 59 Notes: a Average of monthly data at Cal Poly SLO Weather Station 52 1987 — 2018. b Average Calendar Year is not the sum of the monthly average, but rather a historical annual average over the period of record from 1871— 2018. 3.6.2 Existing Management Plans There are numerous groundwater and water management plans and study reports that cover either the whole or portion of the SLO Basin. These plans and reports are described in the following subsections, along with brief descriptions of how they relate to the management of current water supply, projected water supplies, and land use. j.6.z.1 �Lu tsasin Lnaracterization and Monitoring Well Installation The SLO Basin Characterization and Monitoring Well Installation documents the available published reports, private well reports, well completion reports, geologic logs, and other data that were reviewed to generate a comprehensive compilation of the current understanding of the hydrogeologic setting of the SLO Basin. This information is intended to provide the basis of knowledge for future planning and management activities performed under the requirements of GMA, including the development of a hydrogeologic conceptual model, construction of a numerical groundwater model, and development of a GSP. 3.6.2.2 San Luis Obispo County Master Water Report (2012) The County's Master Water Report (MWR) is a compilation of the current and future water resource management activities being undertaken by various entities within the County and is organized by Water Planning Areas (WPA). The MWR explores how these activities interrelate, analyzes current and future supplies and demands, identifies future water management strategies and ways to optimize existing strategies, and documents the role of the MWR in supporting other water resource planning efforts. The MWR evaluates and compares the available water supplies to the water demands for the different water planning areas. This was accomplished by reviewing or developing the following: • Current water supplies and demands based on available information 23 Page 112 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Description of Plan Area (§ 354.8) • Forecast water demands and water supplies available in the future under current land use policies and designations • Criteria under which there is a shortfall when looking at supplies versus demands • Criteria for analyzing potential water resource management strategies, projects, programs, or policies • Potential water resource management strategies, projects, programs, or policies to resolve potential supply deficiencies 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014) The San Luis Obispo County Integrated Regional Water Management Plan (IRWMP) was initially developed and adopted by the SLOFCWCD in 2005 (GEI Consultants, 2005), and has been updated several times. The SLOFCWCD, in cooperation with the SLOFCWCD's Water Resources Advisory Committee (WRAC), prepared the 2014 IRWMP (San Luis Obispo County, 2014) to align the region's water resources management planning efforts with the State's planning efforts. The IRWMP is used to support the region's water resource management planning and submittal of grant applications to fund these efforts. The IRWMP includes goals and objectives that provide the basis for decision -making and are used to evaluate project benefits. The goals and objectives reflect input from interested stakeholders on the region's major water resources issues. These goals and objectives help secure and enhance the water supply reliability, water quality, ecosystems, groundwater, flood management and water -related communication efforts across the entire region. In addition, the IRWMP identifies resource management strategies, recognizes other funding opportunities and includes a list of action items (projects, programs, and studies) that agencies around the region are undertaking to achieve and further these goals and objectives. The IRWMP is currently being updated with a DWR submittal target date of December 2019 and adoption by local agencies scheduled for Summer 2020. 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan (2016) The City's Urban Water Management Plan (UWMP) describes the City's current and future water demands, identifies current water supply sources, and assesses supply reliability for the City. The UWMP describes the City's use of groundwater and its support for efforts to avoid overdraft by developing additional sources. The UWMP provides a forecast of future growth, water demand, and water sources for the City through 2035. These sources include water conservation, Nacimiento Water Project, Salinas Reservoir (Santa Margarita Lake), Whale Rock Reservoir, SLO Basin groundwater, and recycled water from the WRRF. The UWMP identifies beneficial impacts to groundwater quality through the use of these sources. 3.6.3 Existing Groundwater Regulatory Programs 3.6.3.1 Groundwater Export Ordinance (2015) In 2015, County of San Luis Obispo adopted an Exportation of Groundwater ordinance (County Code Chapter 8.95) that requires a permit for the export of groundwater out of a groundwater basin or out of the County. An export permit is only approved if the Department of Public Works Director or his/her designee finds that moving the water would not have any adverse impacts to groundwater resources, such as causing aquifer levels to drop, disrupting the flow of neighboring wells, or resulting in seawater intrusion. Export permits are only valid for one year. 3.6.3.2 Countywide Water Conservation Program Resolution 2015-288 (2015) The ordinance also identified areas of severe decline in groundwater elevation and properties overlying these areas would be further restricted from planting new or expanding irrigated agriculture except for those converting irrigated agriculture on the same property into a different crop type. This resolution applies to the Nipomo Mesa Water Conservation Area which is part of the Santa Maria Groundwater Basin, 24 Page 113 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO the Los Osos Groundwater Basin, and the Paso Robles Groundwater Basin. Therefore, it is not applicable to the SLO Basin. 3.6.3.3 Agricultural Order R3-2017-002 (2017) In 2017 the CCRWQCB issued Agricultural Order No. R3-2017-0002, a Conditional Waiver of Waste Discharge Requirements for Discharges from Irrigated Lands. The permit requires that growers implement practices to reduce nitrate leaching into groundwater and improve surface receiving water quality. Specific requirements for individual growers are structured into three tiers based on the relative risk their operations pose to water quality. Growers must enroll, pay fees, and meet various monitoring and reporting requirements according to the tier to which they are assigned. All growers are required to implement groundwater monitoring, either individually or as part of a cooperative regional monitoring program. Growers electing to implement individual monitoring (i.e., not participating in the regional monitoring program implanted by the Central Coast Groundwater Coalition [CCGC]) are required to test all on -farm domestic wells and the primary irrigation supply wells for nitrate or nitrate plus nitrite, and general minerals (including, but not limited to, TDS, sodium, chloride, and sulfate). 3.6.3.4 Water Quality Control Plan for the Central Coast Basins (2017) The Water Quality Control Plan for the Central Coastal Basin (Basin Plan) was most recently updated in September 2017 by the SWRCB. The objective of the Basin Plan is to outline how the quality of the surface water and groundwater in the Central Coast Region should be managed to provide the highest water quality reasonably possible. The Basin Plan lists beneficial users, describes the water quality that must be maintained to allow those uses, provides an implementation plan, details SWRCB and CCRWQCB plans and policies to protect water quality, and a statewide surveillance and monitoring program as well as regional surveillance and monitoring programs. Present and potential future beneficial uses for inland waters in the SLO Basin are: surface water and groundwater as municipal supply (water for community, military or individual water supplies); agricultural; groundwater recharge; recreational water contact and non -contact; sport fishing; warm fresh water habitat; wildlife habitat; rare threatened or endangered species; and spawning, reproduction, and/or early development of fish. Water Quality Objectives for both groundwater (drinking water and irrigation) and surface water are provided in the Basin Plan. 3.6.3.5 California DWR Well Standards (1991) Under the CWC Sections 13700 to 13806, DWR has the responsibility for developing well standards. DWR maintains these standards to protect groundwater quality. California Well Standards, published as DWR Bulletin 74, represent minimum standards for well construction, alteration, and destruction to protect groundwater. Cities, counties, and water agencies in California have regulatory authority over wells and can adopt local well ordinances that meet or exceed the statewide Well Standards. When a well is constructed, modified or destroyed a well completion report is required to be submitted to DWR. 3.6.3.6 Requirements for New Wells (2017) Senate Bill 252 effective on January 1, 2018. SB 252 requires well permit applicants in critically overdrafted basins to include information about the proposed well, such as location, depth, and pumping capacity. The bill also requires the permitting agency to make the information easily accessible to the public and the GSA. As of 2019, these requirements are under review by DWR. This bill is not applicable because the SLO Basin is not a critically overdrafted basin. 25 Page 114 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO 3.6.3.7 Title 22 Drinking Water Program (2018) The 2018 SWRCB DDW regulates public water systems in the State to ensure the delivery of safe drinking water to the public. A public water system is defined as a system for the provision of water for human consumption through pipes or other constructed conveyances that has 15 or more service connections or regularly serves at least 25 individuals daily at least 60 days out of the year. Private domestic wells, wells associated with drinking water systems with less than 15 residential service connections, and industrial and irrigation wells are not regulated by the DDW. Additional information regarding the public water systems can be found using the following link: https://sdwis.waterboards.ca.gov/PDWW/JSP/WaterSystems.jsp?PointOfContactType=none&number=&na me=&county=San%20Luis%200bispo The SWRCB DDW enforces the monitoring requirements established in Title 22 of CCR for public water system wells, and all the data collected must be reported to the DDW. Title 22 also designates the regulatory limits (e.g., maximum contaminant levels [MCLs]) for various waterborne contaminants, including volatile organic compounds, non-volatile synthetic organic compounds, inorganic chemicals, radionuclides, disinfection byproducts, general physical constituents, and other parameters. 3.6.3.8 Waterway Management Plan — San Luis Obispo Creek Watershed (2003) The San Luis Obispo Creek Watershed Waterway Management Plan was created in response to several damaging floods that occurred in 1969, 1973, and 1995 that caused widespread damage throughout the watershed that includes out -of -bank flooding and extensive bank erosion. This plan identifies management problems and needs of the waterways, detailed hydrologic analyses of the watershed and its main tributaries. The plan also presents a Stream Management and Maintenance Program for the waterways of the watershed that outlines the planning, design, and permitting required to fully implement the program and a Drainage Design Manual that contains revised policies for floodplain and stream corridor management and redesigned flows for stream channels within the City boundary. 3.6.3.9 Incorporation Into GSP Information in these various plans mentioned above has been incorporated into this GSP for consideration in the development of Sustainability Goals, when setting Minimum Thresholds and Measurable Objectives, and was considered during development of Projects and Management Actions to provide consistency among the above listed plans to achieve groundwater sustainability in the SLO Basin. 3.6.3.10 Limits to Operational Flexibility Some of the existing management plans and ordinances will limit operational flexibility. These limits to operational flexibility have already been incorporated into the sustainability projects and programs included in this GSP. Examples of limits on operational flexibility include: • The Groundwater Export Ordinance requires county approval to export of water out of the SLO Basin. This is likely not a significant limitation because exporting water out of the SLO Basin hinders sustainability. • Title 22 Drinking Water Program regulates the quality of water that can be recharged into the SLO Basin. 3.7 CONJUNCTIVE USE PROGRAMS There are no active conjunctive use programs currently operating within SLO Basin. 26 Page 115 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 3.8 LAND USE PLANS Description of Plan Area (§ 354.8) The County and City have land use authority in the SLO Basin and the other MOA Parties do not. However, SGMA requires the GSAs to consider land use documents by the overlying governing agencies when making decisions. Government Code Section 65350.5 and 65352 require review and consideration of groundwater requirements before the adoption or any substantial amendment of a city's or county's general plan. The planning agency shall review and consider GSPs and any proposed action should refer to the GSA and GSP. Land use is an important factor in water management as described below. The following sections provide a general description of these land use plans and how implementation may affect groundwater supply. 3.8.1 City of San Luis Obispo General Plan The General Plan is the principal tool the City uses when evaluating municipal service improvements and land use proposals. Every service the City provides to its citizens can trace its roots back to goals and policies found in the General Plan. General Plan goals, policies, and implementation measures are based on an assessment of current and future needs and available resources. The land use element designates the general distribution and intensity of land uses, including the location and type of housing, businesses, industry, open space, and education, public buildings, and parks. Figure 3-12 shows the City's Land Use Map. Land Use Element �a�a ue,*�eurewcc soi Pt.nnlm sm..e. �evnmec��� L duze 0!1Ee KES Planning Sub.re. oEULE 50[Plmnng 0uharea o� N Fee.q iv Ify.�ra/IR�aWRak PxAf Z Wi N Rrmw - IVater 6ccy LLl Figure 3-12. City Land Use Map The City manages its housing supply growth so that it does not exceed one percent per year on average, excluding dwellings affordable to residents with extremely low, very low or low incomes as defined by the Housing Element. The City decided to adopt a Water and Wastewater Element addressing water resources and wastewater services because of the vital role of these resources and the far-reaching impacts of water policies on community growth and character. This element translates the Land Use Element's capacity for development into potential demand for water supply and wastewater services. This element outlines how the City plans to provide adequate water and wastewater services for its citizens, consistent with the goals 27 Page 116 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO and policies of other General Plan elements. As stated in the General Plan, the City has an adequate water supply to serve the community's existing and future water needs. The City envisions groundwater playing an important role in ensuring continued resiliency in its water supply portfolio. 3.8.2 County of San Luis Obispo General Plan The 2014 County General Plan contains three pertinent elements that are related to land use and water supply. Pertinent sections include the Land Use, Agricultural, and Inland Area Plans elements. The County's General Plan also contains programs that are specific, non -mandatory actions or policies recommended by the Land Use and Circulation Element (LUCE) to achieve community or area wide objectives. Implementing each LUCE program is the responsibility of the County or other public agency that is identified in the program. Programs are recommended actions rather than mandatory requirements. Implementation of any program by the County should be based on consideration of community needs and substantial community support for the program and its related cost. The SLO Basin is within the San Luis Obispo Planning Area and South County Planning Area. The planning areas do not conform to the SLO Basin boundaries but do provide a general representation of the land use in the areas. Figure 3-13 and Figure 3-14 shows the planning areas and land uses. �1 North County Planning Area i DLPAFt wENY of ` ,xoaaoan r PLANNING AND UUILUING 0 1 2 4 pfl Coastal Zone as a COaslal Y.ne A t� Miles SAN LU 15 0BISPO PLANNING AREA AURAL LAND USE CATEGORY MAP II d _ LEGENU A�soa.y URLvan�eouna.n con,n��,a San Luis Obispo Planning Area OW face South County Planning Area /_J `. ,\ sant�ay mam snA I _. avloeena, oPi Oo eP n no6Yafl Figure 3-13. County Land Use Map (San Luis Obispo Planning Area) The General Plan Framework for Planning does not provide tabular assessment of land use types and acres, or population projection estimates within the San Luis Obispo Planning Area and South County Planning Area. Therefore, projected demands and supplies based on land use aren't identified for the SLO Basin in the Land Use element. W Page 117 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO North County P]anning Area - Fas„narea Hann i DEPARTMENT OF PLANNING AND BUILDING ..nx sao u»� lx PaSeaSMArea SwN m�a o 005 1 2 MEes SOUTH COUNTY PLANNING AREA SAN LUIS OBISPO SUB AREA SOUTH RURAL LAND USE CATEGORY MAP San Luis Obispo Planning Area 3 - nrea fb LEGEND F-7 —.1 OP�a �a �tlary o P a —Ma South County Planning Area j0 �,/ i' l i_ s xexrmcfoxa ] , Afultl{ntl vu cahpory �� o e �a Santos BaY HNSW Nea �PUN'c FaaRy � _ Re¢eaam ^ M�a ^ Reu 1Mu�Famly Resitlerti l5 Durban Resitlemal5ln�e Family S3nl,n'a9aYMark Sub Prza SwN `O - 1`fIF 1 Figure 3-14. County Land Use Map (South County Planning Area) 3.8.3 Los Ranchos/Edna Village Plan More specifically, the Los Ranchos/Edna Village Plan establishes a vision for the future that will guide land use and transportation over the next 20 years. This village plan is part of Part III of the LUCE of the County General Plan within the San Luis Obispo Planning Area. The Framework for Planning (LUCE Part 1) is the central policy document, while this plan contains programs more specifically applicable to the Los Ranchos/Edna village area. In accordance with the Framework for Planning, allowable densities (intensity of land use) are established (Figure 3-15). The San Luis Obispo Area Plan contains regional land use and circulation goals, policies, and programs that also apply to Los Ranchos/Edna. Table 3-7 and summarize the acreage and distribution of each land use category in Los Ranchos/Edna village. Rural land use acreage is summarized in the Framework for Planning. 29 Page 118 of 1183 SLO Basin Groundwater Sustainability Plan Description of Plan Area (§ 354.8) County of SLO and City of SLO Table 3-7. Los Ranchos/Edna Land Use Acreage Land Use Categovies Acreage Agriculture Rural Lands Recreation 235 Open Space 0 Residential Rural 394 Residential Suburban 250 ResidentiaF Single Family 50 Residential Muiti-Family 0 office and PFOfesslonal 0 Commercial Retail 0 Commercial Service 0 Industrial 0 Public Facilities 10 Dalidio Ranch 0 Total 957 333 _ . ~ INc Mlles n� qt}5 n25 n5 L! aA1J 1003E GATEGO Hit% San Luis Obispo Planning Area Ltl°�w909°°�°'ry op maa.,Rd� r�i Pannnq SW w 0..Ma 1 � Coo RmctasElu VRL aa—noS.eaMe vn� Cnn.nMioal Relal South County Planning Area raMn.�c'd'ev,. { ik+rvR l]Bwo Bwaim SWr+ j Mu4Lwdllee Ckt.q..s Ndlc Feollry Wtl9YlUs WRY LNW9 �' �PWgWnI unl rxmty wmtn IM FurM �~ p.ua.n�iy ayN .m .�" V.8 fi.l iwntl 3 W ima `roes _ Figure 3-15. Los Ranchos/Edna Land Use Map 3.8.4 Plan Implementation Effects on Existing Land Use This section to be completed after GSP is complete. 30 Page 119 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 3.8.5 Plan Implementation Effects on Water Supply This section to be completed after GSP is complete. 3.8.6 Well Permitting/Ordinance This section to be completed after GSP is complete. 3.8.7 Land Use Plans Outside of Basin Description of Plan Area (§ 354.8) The Parties submitting this GSP have not included information regarding the implementation of land use plans outside of the SLO Basin as adjacent basins are also required to implement SGMA and their GSPs will require them to achieve sustainable groundwater management. 3.9 MANAGEMENT AREAS This section to be completed after GSP is complete. 3.9.1 Reason for Creation 3.10 ADDITIONAL GSP ELEMENTS, IF APPLICABLE 31 Page 120 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 4 BASIN SETTING (§ 354.14) Basin Setting (§ 354.14) This section describes the geologic setting of the San Luis Obispo Valley Groundwater Basin (Basin), including the Basin boundaries, geologic formations and structures, principal aquifer units, geologic cross sections, and hydraulic parameter data. The information presented in this chapter, when considered with the information presented in Chapter 5 (Groundwater Conditions) and Chapter 6 (Water Budget), comprises the basis of the Hydrogeologic Conceptual Model (HCM) of the Basin. This section draws upon previously published studies, primarily a hydrogeologic and geologic investigation prepared by GSI for the San Luis Obispo County Flood Control and Water Conservation District (SLOCFCWCD) in 2018, as well as a 1997 draft report, "San Luis -Edna Groundwater Basin Study, Draft Report" (DWR, 1997), which was prepared but never finalized for official publication, and a 1991 report by Boyle Engineering (Ground Water Basin Evaluation) that was prepared for the City. The data and information presented in this section is not intended to be exhaustive but is a summary of the relevant and important aspects of the Basin geology that influence groundwater sustainability. More detailed information can be found in the original reports discussed above. This section presents the framework for subsequent sections on groundwater conditions and water budgets. As part of the GSP process, a numerical groundwater model is being developed for the Basin to use as a tool in the planning process (Appendix ZZ). Much of the information comprising the HCM presented in Chapters 4, 5, and 6 of the GSP is applied directly to the development of the groundwater model. Physical data on the geology and hydrogeologic parameters of the Basin presented in Chapter 4 are used to develop the model structure and parameterization. Data on groundwater conditions and water budget presented in Chapters 5 and 6 are used in model calibration. Multiple sources and types of data are presented in Chapters 4, 5, and 6. Some of this data, such as rainfall amounts, depth to groundwater, and depth to bedrock, is directly measurable and involves a low degree of uncertainty. Other data, such as aquifer transmissivity, is based on calculations and interpretations of observed data, but is not directly measurable, and so involves a greater amount of uncertainty than direct measurements. And finally, values presented in the water budget are primarily derived from analysis of related data; almost none of the water budget components are directly measurable, and so involve more uncertainty than the previously discussed data types. 4.1 BASIN TOPOGRAPHY AND BOUNDARIES The Basin is oriented in a northwest -southeast direction and is composed of unconsolidated or loosely consolidated sedimentary deposits. It is approximately 14 miles long and 1.5 miles wide. It covers a surface area of about 12,700 acres (19.9 square miles). The Basin is bounded on the northeast by the relatively impermeable bedrock formations of the Santa Lucia Range, and on the southwest by the formations of the San Luis Range and the Edna fault system. The bottom of the Basin is defined by the contact of permeable sediments with the impermeable bedrock Miocene -aged and Franciscan Assemblage rocks (DWR, 2003). A topographic map displaying the Basin boundaries is presented in Figure 4-1, which also displays the watershed areas of the San Luis Obispo Creek and Pismo Creek drainages. An aerial photo of the Basin area is presented in Figure 4-2. Elevations within the Basin range from over 500 feet above mean seal level in the southeastern extent of Edna Valley, to under 100 feet above mean sea level where San Luis Obispo Creek flows out of the Basin. The Basin is commonly referenced as being composed of two distinct valleys, with the San Luis Valley in the northwest and the Edna Valley in the southeast. The San Luis Valley comprises approximately the northwestern half of the Basin. It is the area of the Basin drained by San Luis Obispo Creek and its 32 Page 121 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO tributaries (Prefumo Creek and Stenner Creek west of Highway 101, Davenport Creek and smaller tributaries east of Highway 101). Surface drainage in San Luis Valley drains out of the Basin flowing to the south along the course of San Luis Obispo Creek toward the coast in the Avila Beach area, approximately along the course of Highway 101. The San Luis Valley includes part of the City and California Polytechnic University (Cal Poly) jurisdictional boundaries, while the remainder of the valley is unincorporated land. Land use in the City is primarily municipal, residential, and industrial. The area in the northwest part of the Basin, along Los Osos Valley Road, has significant areas of irrigated agriculture, primarily row crops. The Edna Valley comprises approximately the southeastern half of the Basin. The primary creeks that drain the Basin are the east and west branches of Corral de Piedras Creek; the Corral de Piedras Creek tributaries join to form Pismo Creek, draining south out of the Edna Valley into Price Canyon. Canada de Verde Creek is also a significant tributary that flows south out of the Basin in the extreme southeastern part of Edna Valley, ultimately joining Pismo Creek (Figures 4-1 and 4-2). The Edna Valley includes unincorporated lands, including lands associated with various private water purveyors. The primary land use in the Edna Valley is agriculture. During the past two decades, wine grapes have become the most significant crop type in the Edna Valley. The primary weather patterns for the Basin are derived from seasonal patterns of atmospheric conditions that originate over the Pacific Ocean and move inland. As storm fronts move in from the coast, rainfall in the area falls more heavily in the mountains, and the Basin itself receives less rainfall because of a muted rain shadow effect. Average annual precipitation ranges from approximately 18 inches throughout most of the Basin to about 22 inches in relatively higher elevation areas near the City and Cal Poly (Figure 4-3). The time series of annual precipitation for the period of record from 1871 to 2018 at the Cal Poly weather station is presented in Figure 3-11. The average rainfall at this location is 21.69 inches, with a standard deviation of 8.71 inches. The historical maximum is 49.99 inches, which occurred in 1884. The historical minimum is 4.56 inches, which occurred in 2013. The physical definition of the Basin boundary is the occurrence of unconsolidated or loosely consolidated saturated sediments down to the contact with the basement rock of the Miocene -aged formations and Franciscan Assemblage. (The geologic units will be described in more detail Section 4-4.) Figure 4-4presents a surface defining the bottom boundary of the Basin, based on the elevation of bedrock surface below the Basin sediments. There is a topographic high point in the underlying bedrock elevation between the San Luis Valley and Edna Valley sub -areas. As shown, the watershed divide and the bedrock divide are not coincident. Figure 4-5 presents contours of total thickness of the Basin sediments; the inset figure displays the thickness of sediments in a longitudinal cross section. It is apparent from Figure 4-6 that the sediments of the Edna Valley have significantly greater thickness than those of the San Luis Valley. The longitudinal profile of the Basin from the northwest on the left of the figure to the southeast on the right indicates the watershed divide present in the vicinity of Biddle Ranch Road, indicated on Figure 4-4 and Figure 4-5. Precipitation that falls west of that divide ultimately flows to Davenport and San Luis Obispo Creeks, and precipitation that falls east of that divide flows to Corral de Piedras Creek or the other small tributaries, ultimately flowing to Pismo Creek south of the Basin. 33 Page 122 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) 601) t d o 16 sco• jun ! g J � �� � roe• r _ e� 900'� ` 16�v 400, r ass 7-a 107 TANS F _ 41 a•�{{ r r �d ;,pd Apo G 24p- �O• 0 xo s va• Explanation S .rap. Elevation Contour N Q Bulletin 118 Basin Boundary 9°0• E_J City Boundary • N Major Road Watercourse bpp. �o Waterbody 00 a �0 's o ua `" . Foy. JD 250. 4p0, O. q '06, 7 O• P I $ rm 0��:4 '�• B E A C H 1 w - t Prepared for: Autnor: AS Qate' 11l2yp19 N �j � - �1Mnes 1 References: S cjWivnaLa SYert C MAD 9903 nialePlBne Califpmia V FIP$ 0405 Feel Coor2; Datum vn� Lambert Cvn19&m Cynic 2.San : Luis O iWm Con 1ea9 2.San Luis 06ispo County 0 0425 0S5 N 1.7 3 U1 Gs SAN LUIS OBISPO VALLEY BASIN GSP —m n'ate`s oy oyf � A1\ o q PsD. . 9�0 r>oo. 600, �'a• �` Sao' o. _ 00 ba• sro9' �d 6 �M1oa Taoo ' aPp Vfl� f p�' M11G9. Topographic Map Figure 4-1 34 Page 123 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) �'z y' Explanation 0 Bulletin 118 Basin Boundary ww �R — — E �' l ► _ 't y t J City Boundary j., •• /�/ Major Road �. c firs ti Watercourse Waterbody w � � r• .L S n 081 S PO - it � ni L� �n �� :,\ �. � • - �•i l i '"_'—.-_. � .... .. ,. - ' ` w.>Z`. ►'f► ON ■ i r 01 f-- ♦ � '' ,O . �r � L[ is eF PI SM01 ~\� - At BEACH •fir. '�••r - . ' r i Prepared for: w 1 References, 9%k Au1110f: AS pate: 11 r25r"0 P 0 1 Y 0 0.25 0.5 �Mk5 1 CaaMnefemtert NAB L 9d r StaleP19n0 California V FIPS 0405 Feet Lambert Can193m CAnic PyqwtDatum �'^x W5 Obi Wri[an1g89 x$gg County 0 0.425 0.85 7.7 w 2018 3- oigigk6e 2018 SAN LUIS OBISPO VALLEY BASIN GSP �VjkxTwtem Aerial Photograph Figure 4-2 35 Page 124 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 61. Basin Setting (§ 354.14) < Explanation `t7X�— ��` ' O Bulletin 118 Basin Boundary Line of Equal Average Annual off Precipitation (2-inch Interval) r ' Road Ole, . ly, j 1 y m 1 i " Prepared for: Ny References: Author'. ON ' Date: ll ON 019 lty 0 025 0.5 ■■,y\`{j\ 1 Miles L Cocro naLa System: NAD 1883 StatePlane California V RPS 0405 Feet Projection. Lam6art Conformal Conic Datum. North Arnerican 1983 2- San Luis Ohispo County 0 0.425 0.85 1.7 3. PRISM Climate Group (Oregon State University) SAN LUIS OBISPO VALLF Y BASIN GSP i K lometere Notes: 1. Precipitation data from'. PRISM30 yr Normal sataset (1991-2010) Annual Precipitation Figure 4-3 36 Page 125 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 0- , 300 1Iigh-y191 SLO Airp5 rt Cwli Courr. n � 209 a 7 0 C 9 ` v C ,gU 9E 13 ROCK L IN -2001 Distance in Miles t° Pacific Ocean Basin Setting (§ 354.14) j_. �1 • ~,� ice-; r+yr RE La AL Bedro ivide J� ram—JAMF ..4 A4• EAST • 0 _20. soo , . 20 e 40o ,•!1 r/ is , • l — — -- — — — — f — — — — — — — - — — — — — — — — — — — — —r— — — Prepared for: p References: V 1. Cectio nate SYstem'. NAD al C StatePlane California V FIFE 0405 Feet Author' NP A 0 0.25 0.5 1 Pr°jedion'. Lam Berl Conformal Conic i, 2. San Norlhbispo County 3 Oate10f31f2019 Miles 2. San Luis 061sp° County 0 0.425 0.05 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP � Kilometers Explanation O Bulletin 118 Basin Boundary Bedrock Elevation Contour - Index Bedrock Elevation Contour - Minor o Bedrock Depth Data Point Longitudinal Section Line Road Bedrock Elevation (feet amsl) 0 -100 0 0 0 100 200 300 I Watershed Divider ,f N' ..! + tift� �. y. a►, y � ./ `' � rim Bottom Elevation of Basin Figure 4-4 37 Page 126 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) YIM Explanation Bulletin 118 Basin Boundary • �� i� . ' { ; sti�: -r +' /l Sediment Thickness Contour - Index f � �; • 0 1 1 _ Sediment Thickness Contour - Minor Io� •� � (Orpr dal F {�' �!a,Rd y . Bedrock Depth Data Point Al -ti' ". f.% rf Longitudinal Section Line Road 20 Sediment Thickness (feet) 0 5an'Criis Obispo.- `" . 0 100 e r 200 R t ` 300 r + Jb 400 a � .r Bedro ivide too to F r •'g Watershed Divide r f - r • �AAl AW , m 1 WEST EAST - SCo O - 900 400 1 0;11ji- ! • 300 lighway 101 5L0 Air{5aR [call Cour:r. 3°0 a ✓I } r -:• ra Ezaa zoo \ 0 l J SEDIMENT- 1 9 4 _0ekk7 is 100 eEDROCK J 8EDH4G 100 t1 • I uJ -200 U .20015 • ��0�,� ro yam. f Distance in Miles t° �d�s i 1"i -- - - - , I _ — — — — — — — — A4F -- ' Pacific Ocean - - - - - - - - ,�- - - p Y. Prepared for: p I References: . Author' NP Oate'. 10f31 f2019 V A 0 0.25 05 ■1 1 Miles 1. CoortlinaLa SYste C NA D al C StatePlane Caldornia V FIFE 0405 Feet Projedlon'. Lam Bsrl Conformal Conic 1993 2. San Luis Obispo County 2. tuwSan Northbispo Co my 0 0.425 0.05 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP �/■.\4`,\ � Kilometers Notes: 1. Contourinterval= 40feet Thickness of Basin Sediments Figure 4-5 38 Page 127 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO 4.2 PRIMARY USERS OF GROUNDWATER The primary groundwater users in the Basin include municipal, agricultural, and domestic (i.e., rural residential, small community water systems, and small commercial entities). These entities are discussed in more detail in Chapter 2 of this report. The City currently receives most or all of its supply from surface water sources including Whale Rock Reservoir, Santa Margarita Reservoir, Nacimiento Reservoir, and recycled water (Figure 3-3). However, it maintains its network of production wells in standby mode for emergency supply and intends to utilize groundwater as a resource to meet future water demand. The mutual and private water companies, domestic and agricultural users in the Edna Valley rely almost exclusively on groundwater, although some have water rights along East and West Corral de Piedras Creeks. No surface water points of diversion along San Luis Obispo Creek are present in the Basin. 4.3 SOILS INFILTRATION POTENTIAL Saturated hydraulic conductivity of surficial soils is a good indicator of the soil's infiltration potential. Soil data from the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey Geographic Database (SSURGO) (USDA NRCS, 2007) is shown by the four hydrologic groups on Figure 4-6. The soil hydrologic group is an assessment of soil infiltration rates that is determined by the water transmitting properties of the soil, which includes hydraulic conductivity and percentage of clays in the soil relative to sands and gravels. The groups are defined as: • Group A — High Infiltration Rate: water is transmitted freely through the soil; soils typically less than 10 percent clay and more than 90 percent sand or gravel. • Group B — Moderate Infiltration Rate: water transmission through the soil is unimpeded; soils typically have between 10 and 20 percent clay and 50 to 90 percent sand • Group C — Slow Infiltration Rate: water transmission through the soil is somewhat restricted; soils typically have between 20 and 40 percent clay and less than 50 percent sand • Group D — Very Slow Infiltration Rate: water movement through the soil is restricted or very restricted; soils typically have greater than 40 percent clay, less than 50 percent sand A higher soil infiltration capacity does not necessarily correlate to higher transmissivity in the underlying aquifer, but it may correlate to greater recharge potential in localized areas. This will be discussed in more detail in Chapter 5. 39 Page 128 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) T �r RIP P I s M ❑ B E A C H •• �, ��*� t Explanation Q Bulletin 118 Basin Boundary ��►► X0. -- yam► Soils by Hydrologic Group .��OdP- 1 A- High Infiltration Rate /� B - Moderate Infiltration Rate r C - Slow Infiltration Rate ❑ - Very Slow Infiltration Rate All Other Features City Boundary Major Road Watercourse y+r 4r4odoom& Waterbody 00, J _ . F,kWK FARM k0101 �— �• r B�pO'' trd dd — x i 7 ■ /r i ` pr Oa`` J . d Al 41 kr ,- d0k. t� Prepared for: N References: t CeMion Lambert C NAB 79C Conic California V FIP$ 0405 FeH Au[nor: EC 0 0.25 05 Datum: vn Lambert Cant OW Conic O.W 11121% 19 Miles 2. San uis; Obispo C n my 2. San Luis Obispo County 'k 0 A 0 0425 0.85 t 7 3 119GS SAN LUIS OBISPO VALLEY BASIN GSP Kil. ' rs Soil Hydrologic Groups Figure 4-6 Page 129 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 4.4 REGIONAL GEOLOGY Basin Setting (§ 354.14) This section provides a description of the geologic formations and structures in the Basin. These descriptions are summarized from previously published reports. Figure 4-7 displays a stratigraphic column presenting the significant geologic formations within the Basin. Figure 4-8 presents a surficial geologic map of the Basin and surrounding area. Figure 4-9 displays the locations of lithologic data used for this plan, and the section lines corresponding to cross sections in the following figures. Geologic cross sections are presented in Figure 4-10 through 4-22. The selected geologic cross sections illustrate the relationship of the geologic formations that comprise the Basin and the geologic formations that underlie and bound the Basin. The cross sections displayed on Figure 4-10 through Figure 4-21were directly adopted from the SLO Basin Characterization Report (GSI, 2018). 4.4.1 Regional Geologic Structures The primary geologic structures of significance to the hydrogeology of the Basin are the Edna Fault Zone and the adjacent Los Osos Fault Zone, which together form the southwestern boundary of the Basin through the uplift of the Franciscan and Monterey Formation strata in the San Luis Range southwest of the faults. The Edna and Los Osos Faults are normal faults, indicating primary displacement motion is vertical rather than lateral (Figure 4-8). There are some disconnected and unnamed fault splays mapped in the area south of the airport. 4.4.2 Geologic Formations within the Basin For the purpose of this plan, the geologic units in the Basin and vicinity may be considered as two basic groups; the Basin sediments and the consolidated bedrock formations surrounding and underlying the Basin. The consolidated bedrock formations range in age and composition from (1) Jurassic -aged serpentine and marine sediments to (2) Tertiary -aged marine and volcanic depositions. Compared to the saturated sediments that comprise the Basin aquifers, the consolidated bedrock formations are not considered to be significantly water -bearing. Although bedding plane and/or structural fractures in these rocks may yield small amounts of water to wells, they do not represent a significant portion of the pumping in the area. The delineation of the Basin boundaries is defined both laterally and vertically by the contacts of the Basin sedimentary formations with the consolidated bedrock formations. From a hydrogeologic standpoint, the most important strata in the Basin are the sedimentary basin fill deposits that define the vertical and lateral extents of the Basin. These include recent and older deposits of terrestrial sourced sediments, underlain in the Edna Valley by older marine sedimentary units. Figure 4-7 presents a stratigraphic column of the significant local geologic units. Figure 4-8 presents a map of the Basin vicinity (assembled from a mosaic of the Dibblee maps from the San Luis Obispo, Pismo Beach, Lopez Mountain, and Arroyo Grande NE quadrangles) showing where the various formations crop out at the surface. Fault data displayed in Figure 4-8 were acquired via the USGS Earthquake Hazards Program. The Quaternary fault and fold database from which the shapefiles are derived was published in 2006 and cites a wide variety of published sources. Fault traces within the shapefile represent surficial deformation caused by earthquakes during the Quaternary Period (the last 1.6 million years). Figure 4-8 also displays the Basin boundaries defined in DWR Bulletin 118. Inspection of Figure 4-8 indicates that the Bulletin 118 Boundary lines for the Basin boundary do not match up precisely with the most recently mapped extent of the water -bearing formations based on GSI (2018). This is likely an artifact of previous mapping being performed at a larger (statewide) scale. The water -bearing sedimentary formations and the non -water -bearing bedrock formations are briefly described below. 41 Page 130 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Prepared Far: SAN L0S ONSPO VALLEY BASIN GSP Basin Setting (§ 354.14) MILLION EPOCH I PERIOD I YFARSAGO mp mo D RECENT AND 01 DFF 4I 111v,1k, y y pn Z A oa PASC A06LES FORMA70N z K m 20 Squae PISMO fk11 ,,, FQRMA` ON Mc'®Ao lgu�6au one p m z m D GARF AGA LORMATrDN O A Z m OB 3110 "WATICIN 24 IINi'➢NFUHIVI IY 66 SERPENTINITE n 0 0 N 144 M Notes: i.naa�etl wm cnippina ieaT. Skratigraphic Column 4-7 Page 131 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) F0 i Explanation — Cross Section Line 0 Bulletin 118 Basin Boundary Potential Boundary Adjustment Major Road N Fault Geology +=i Volcanic Intrusive Rocks Obispo Formation — -V. Franciscan Assemblage ~ r Serpentine B' 1 -�► 13- 2' Paso Robles __ a,r•�. Recent Alluvium I �!` Pismo Formation 1, Monterey Formation Atascadero Formation a=, Toro Formation Prepared for: Author: A6 Da[e. 11;2512019 N A 0 0.25 0.5 smiles 1 References: 1, Coordinate System, NAD S[atePlane California V FIP50405 Feel Projection. lambert Conformalal Conic 2 San North Luis ObisAmpo Cericanoun19a3Vk ry San 2 0 0.425 0.35 N 1.7 3. GeoMap SAN LUIS OBISPO VALLEY BASIN GSP Kilo —to,, Geologic Map Figure 4-8 43 Page 132 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 4.4.2.1 Alluvium Basin Setting (§ 354.14) The Recent Alluvium is the mapped geologic unit composed of unconsolidated sediments of gravel, sand, silt, and clay, deposited by fluvial processes along the courses of San Luis Obispo Creek, Davenport Creek, East and West Corral de Piedras Creeks, and their tributaries. Lenses of sand and gravel are the productive strata within the Recent Alluvium. These strata have no significant lateral continuity across large areas of subsurface within the Basin. Thickness of Recent Alluvium may range from just a few feet to more than 50 feet. Well pumping rates may range from less than 10 gallons per minute (gpm) to more than 100 gpm. However, wells screened exclusively in Recent Alluvium are generally less productive than wells that screen significant thicknesses of the Paso Robles and/or Pismo Formations. 4.4.2.2 Paso Robles Formation The Paso Robles Formation underlies the Recent Alluvium throughout most of the Basin, and overlies the Pismo Formation where present. It is composed of poorly sorted, unconsolidated to mildly consolidated sandstone, siltstone, and claystone, with thin beds of volcanic tuff in some areas. The Paso Robles Formation was deposited in a terrestrial setting on a mildly sloping floodplain that has been faulted, uplifted, and eroded since deposition. The Paso Robles Formation is exposed at the surface throughout much of the Edna Valley, except in areas where existing streams have deposited Recent Alluvium on top of it. It is not readily distinguishable from alluvium in geophysical well logs. Locally, the Paso Robles Formation is sometimes distinguished as being yellow in color, with sticky clay. DWR Well Completion Reports with these types of descriptions generally were identified as Paso Robles Formation for the purpose of interpreting the geology in the cross sections. However, it was sometimes difficult to distinguish between Recent Alluvium and Paso Robles Formation in driller's descriptions, and professional judgment and broader context within the Basin were often used when defining the contact between these two units. Wells that screen both the Recent Alluvium and Paso Robles Formation have reported yields from less than 100 to over 500 gpm. 4.4.2.3 Pismo Formation The oldest geologic water -bearing unit with significance to the hydrogeology of the Basin is the Pismo Formation. The Pismo Formation is a Pliocene -aged sequence of marine deposited sedimentary units composed of claystone, siltstone, sandstone, and conglomerate. There are five recognized members of the Pismo Formation (Figure 4-7 ). While all members are part of the Pismo Formation, each member reflects different depositional environments, and the variations in geology may affect the hydrogeologic characteristics of the strata. From the oldest to youngest, the members are: • The Edna Member, which lies unconformably atop the Monterey Formation, and is locally bituminous (hydrocarbon -bearing) • The Miguelito Member, primarily composed of thinly bedded grey or brown siltstones and claystones • The Gragg Member, usually described as a medium -grained sandstone • The Bellview Member, composed of interbedded fine-grained sandstones and claystones • The Squire Member, generally described as a medium- to coarse -grained fossiliferous sandstone of white to grey sands Previous reports have identified the significant thicknesses of sand at depth beneath the Paso Robles Formation in the Edna Valley as the Squire Member of the Pismo Formation. However, it is not clear Page 133 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO whether these are accurately assigned as Squire. Other members of the Pismo Formation may be part of the sequence, and there is some ambiguity as to the actual member assignment. Even in the adjacent Pismo Beach and Arroyo Grande NE quadrangle geologic (Dibblee 2006a, 2006b), there is ambiguity in the geologic nomenclature. In the adjacent geologic maps these quadrangles, a continuous exposure of this unit across the boundary between the two maps is referred to as Pismo Formation in one map (Dibblee 2006b), and Squire Sandstone in the other (Dibblee 2006a). Therefore, it is probably more accurate to generally refer to these units as the Pismo Formation, and not to specifically identify the member designations. This convention will be followed for the remainder of this report. The Pismo Formation is extensive below the Paso Robles Formation in the Edna Valley. Thicknesses of Pismo Formation up to 400 feet are reported or observed in well completion reports and in the cross sections (Figure 4-5). The presence of sea shells in the lithologic descriptions of well completion reports is clearly diagnostic of the Pismo Formation because of its marine origin. Many of the well completion reports in the Edna Valley document the presence of water -bearing blue and green sands beneath the Paso Robles Formation, and these are considered to be largely diagnostic of the Pismo Formation as well. Wells that are completed in both the Paso Robles and Pismo Formations are reported to yield from less than 100 gpm to approximately 700 gpm. 4.4.3 Geologic Formations Surrounding the Basin Older geologic formations that underlie the Basin sediments typically have lower permeability and/or porosity and are generally considered non -water -bearing. In some cases, these older beds may occasionally yield flow adequate for local or domestic needs, but wells drilled into these units are also often dry or produce groundwater less than 10 gpm. Generally, the water quality from the bedrock units is poor in comparison to the Basin sediments. In general, the geologic units underlying the basin include Tertiary -age consolidated sedimentary and volcanic beds (Monterey and Obispo Formations), and Cretaceous -age sedimentary and metamorphic rocks (Franciscan Assemblage). 4.4.3.1 Monterey Formation The Monterey Formation is a thinly bedded siliceous shale, with layers of chert in some locations. In other areas of the County outside of the Basin, the Monterey Formation is the source of significant oil production. While fractures in consolidated rock may yield small quantities of water to wells, the Monterey Formation is not considered to be an aquifer for the purposes of this GSP. Regionally, the unit thickness is as great as 2,000 feet, and the unit is often highly deformed. Water wells completed in the Monterey Formation are occasionally productive if a sufficient thickness of highly deformed and fractured shale is encountered. More often, however, the Monterey shale produces groundwater to wells in very low quantities. Groundwater produced from the Monterey Formation often has high concentrations of Total Dissolved Solids (TDS), hydrogen sulfide, total organic carbon, and manganese. 4.4.3.2 Obispo Formation The Obispo Formation and associated Tertiary volcanics are composed of materials associated with volcanic activity along tectonic plate margins approximately 20 to 25 million years ago. The Obispo Formation is composed of ash and other material expelled during volcanic eruptions. Although fractures in consolidated volcanic rock may yield small quantities of water to wells, the Obispo Formation is not considered to be an aquifer for the purposes of this GSP. 4.4.3.3 Franciscan Assemblage The Franciscan Assemblage contains the oldest rocks in the Basin area, ranging in age from late Jurassic through Cretaceous (150 to 66 million years ago). The rocks include a heterogeneous collection of basalts, which have been altered through high-pressure metamorphosis associated with subduction of the oceanic 45 Page 134 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO crust beneath the North American Plate before the creation of the San Andreas Fault. The current assemblage includes ophiolites, which weather to serpentinites and are common in the San Luis and Santa Lucia Ranges. Although fractures may yield small quantities of water to wells, the Franciscan Assemblage is not considered to be an aquifer for the purposes of this GSP. 4.5 PRINCIPAL AQUIFERS AND AQUITARDS Water -bearing sand and gravel beds that may be laterally and vertically discontinuous are generally grouped together into zones that are referred to as aquifers. The aquifers can be vertically separated by fine-grained zones that can impede movement of groundwater between aquifers, referred to as aquitards. Three aquifers exist in the Basin: Alluvial Aquifer — A relatively continuous aquifer comprising alluvial sediments that underlie the San Luis Obispo Creek and tributary streams, as well as East and West Corral de Piedras Creeks and tributary streams; Paso Robles Formation Aquifer — An interbedded aquifer comprised of terrestrially -derived sand and gravel lenses in the Paso Robles Formation. Pismo Formation Aquifer - An interbedded aquifer comprised of marine sand and gravel lenses in the Pismo Formation. There are no significant aquitards that vertically separate the three aquifers in the Basin over large areas. There may be deposits of clay and silt that are not laterally extensive that locally separate two aquifers, but there is no recognized aquitard in the Basin that separates the aquifers over significant areas. 4.5.1 Cross Sections Eleven cross sections were prepared for this report; three (Al-A2, A2-A3, A3-A4) are oriented along the longitudinal axis of the Basin and eight (B-B' through I -I') are oriented across the Basin, perpendicular to the longitudinal axis (Figure 4-9). All lithologic data was reviewed during the selection of the section line locations. The cross sections display lithology, interpretations of geologic contacts based on available data, well screen intervals, and interpreted and mapped faults. If the geologic interpretation was not clear from the points on the cross section lines, nearby data from other locations was reviewed to provide broader geologic context. Each geologic cross section is discussed in the following paragraphs. The longitudinal axis of the Basin is much longer than the cross basin section lines, the longitudinal axis was divided into three separate cross sections for the sake of clarity and presentation of detail. As part of the work performed for the GSP, CHG performed a passive seismic geophysical plan in the area along Buckley Road south of the airport (Appendix ZZ). Data from this plan resulted in slight adjustments in three of the previously developed cross sections. These data have been incorporated into the cross sections. Cross Section Al-A2 (Figure 4-10) extends approximately 6.5 miles from the northwest extent of the Basin at its boundary with the Los Osos Basin to about 1 mile east of Highway 101. Land surface elevation is about 200 feet AMSL at the northwest extent, and slopes gently downward to about 120 feet AMSL at the southeast extent. Recent Alluvium is exposed at the surface for the entire length of this cross section, ranging in thickness from less than 50 feet near the Los Osos Valley Basin boundary to about 80 feet near the center of the section. The Paso Robles Formation is relatively thin in the northeast where it has been significantly eroded by the alluvium, but thickens to approximately 70 feet in the southeastern part of the section. Marine sands of the Pismo 91 Page 135 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Formation occur below the Paso Robles Formation in the southeastern part of the section, with a maximum thickness of about 50 feet. Cross Section A2-A3 (Figure 4-11) extends approximately 4 miles along the longitudinal Basin axis, starting near Tank Farm Road and cutting obliquely across Buckley Road to just past Edna Road in the southeast. Land surface elevation ranges from approximately 120 feet AMSL in the northwest to more than 270 feet AMSL in the southwest. Along the northwest half of the section line, alluvium is exposed at the surface, with an approximate thickness of 40 to 50 feet. The alluvium is primarily underlain by the Paso Robles Formation with thicknesses ranging from approximately 40 to 80 feet. Just southeast of the airport, the Paso Robles Formation is exposed at the surface, beginning at the point where there is a noticeable rise in land surface elevation. This is approximately coincident with the maximum elevation of the underlying bedrock formations (the bedrock divide that approximates the dividing line between the Edna Valley and the San Luis Valley). A recent geophysical investigation by Cleath-Harris Geologists in the area of the high bedrock elevation has provided greater detail on the Basin geometry in this area. The thickness of the Paso Robles Formation in this area is up to 120 feet. Pismo Formation sediments underlie the Paso Robles Formation in this area, with thickness of about 50 feet in the area of Davenport Creek. The Pismo Formation thickness starts to increase significantly along this section line to the southeast, with about 250 feet of Pismo sediments evident at the southeastern extent of the section line. Several of the borings in this section indicate wells are partially or completely screened in bedrock formations, indicating that the relatively thin saturated portions of the water -bearing sediments did not yield enough water for the purposes of the wells. • Cross section A3-A4 (Figure 4-12) extends about 6.5 miles along the Basin axis from approximately Biddle Ranch Road to the southeast extent of the Basin. Land surface elevation rises from about 250 feet AMSL on the northwest end of the section to over 500 feet AMSL in the southeast. Relatively thin occurrences (40 feet or less) of Recent Alluvium associated with Corral de Piedras Creek and its tributaries are evident in some areas on the western half of this section. In the southeastern extent of the section, the Paso Robles Formation crops out at the surface where the land is beginning to rise to the northern mountains, and is dissected by small streams and valleys in this area. The Pismo Formation sediments reach their maximum thickness of more than 400 feet along the northwestern extent of this section; the thickness of the Pismo gradually thins to about 90 feet at the southwestern extent of the section. • Cross section B-B' (Figure 4-13) extends about 1.5 miles across the Basin perpendicular to the Basin axis in the vicinity of Foothill Boulevard and Los Osos Valley Road. The section line has a land surface elevation of about 180 feet AMSL on the northern end, sloping downward to about 130 feet AMSL along the Basin's long axis, and rising again to about 230 feet AMSL on the southern end. Recent Alluvium is exposed at the surface along this entire section, with thicknesses of about 20 to 30 feet. In the northern half of the section, alluvium is deposited directly on underlying basement rock. In the southern half of the section, the Paso Robles Formation underlies the alluvium with a maximum thickness of about 45 feet. The southern extent of the section crosses the Los Osos Fault Zone. • Cross Section C1-C1' (Figure 4-14) extends from the northern lobes of the Basin boundary, which are formed from alluvium from Stenner and San Luis Obispo Creeks, and trends southward approximately 5.5 miles across the Basin from Cal Poly through the City, approximately along the path of Highway 101. Land surface elevation is about 350 feet at the northern end of the section line on some noticeable hilltops along the line, and slopes downward to an approximate altitude of 80 feet on the southern end. Most of the northern extent of this section has alluvium of about 20 to 40 feet of thickness deposited directly on underlying bedrock. Only in the southernmost 1% miles of the section line, where it crosses the main body of the Basin, do Paso Robles Formation sediments underlie the alluvium. The Paso Robles Formation is about 90 feet thick here, and it is in turn underlain by about 60 feet of Pismo Formation sediments. IA Page 136 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) • Cross Section C2-C2' (Figure 4-15) extends about 1% miles southward through the eastern lobe of the northern part of San Luis Valley. Alluvium is deposited directly on top of basement rock along this section. Alluvium is thin here, ranging from less than 10 feet to about 40 feet. • Cross Section D-D' (Figure 4-16) extends about 2.5 miles southward from a prominent serpentine ridge in the north to the southern Basin boundary. Land surface elevation is about 160 feet on the northern end of the section, sloping down to about 110 feet in the Basin center, and rising to about 180 feet on the southern end. Recent Alluvium is exposed at the surface along most of this section, reaching a maximum thickness of about 80 feet. The alluvium is deposited directly on basement rock through the northern half of the section. In the southern half of the section, approximately 20 to 30 feet of Paso Robles Formation underlies the alluvium. Near the southern extent of the Basin, the section line crosses into the combined Edna -Los Osos Fault Zone, at which point the land surface elevation rises steeply and the Paso Robles Formation crops out at the surface due to the upthrown formations south of the faults. • Cross Section E-E' (Figure 4-17) extends about 2% miles across the Basin in the vicinity of the airport and the area south of Buckley Road. Land surface elevation ranges from about 170 feet on the northern end to 230 feet in the southern end. In the northern half of this section, Recent Alluvium are exposed at the surface. In the southern half, the Paso Robles Formation is exposed. Alluvial thickness in the northern half of the section ranges from about 20 to 70 feet, and is underlain by about 30 to 35 feet of Paso Robles Formation. In the southern half of the section, it crosses into the Edna -Los Osos Fault Zone, and the Paso Robles Formation is upthrown to the point that it is exposed at the surface. Paso Robles Formation thickness ranges from 50 feet to about 100 feet. Sediments of the Pismo Formation underlie the Paso Robles Formation in this area, and are about 25 to 70 feet thick. • Cross Section F-F' (Figure 4-18) extends about 2 miles north to south in the western extent of the Edna Valley area. The Paso Robles Formation is exposed at the surface along most of this section. One small pod of alluvium associated with Davenport Creek is evident in the center of the section. The Paso Robles Formation has a maximum thickness of about 175 feet in this section. It is underlain by about 50 to 60 feet of Pismo Formation sediments in the area north of the Edna Fault Zone. To the south, the section line extends into the Edna Fault Zone. South of the fault, the formations are upthrown, resulting in a small area of Pismo Formation sediments exposed at the surface. • Cross Section G-G' (Figure 4-19) extends about 2 miles through the heart of the Edna Valley area. Land surface elevation ranges from about 300 feet on the north end to more than 350 feet on the south end. A thin veneer of alluvium, about 20 feet thick, that is associated with Corral de Piedras Creek and tributaries is exposed at the surface along much of this section. The Paso Robles Formation crops out in the north of the section, and underlies the alluvium with an average thickness of about 50 to 60 feet. The Pismo Formation displays its largest thickness along this section, with a maximum thickness of about 450 feet near where this section intersects with cross section A3-A4. The southern end of the section line crosses into the Edna Fault zone, and sediments are displaced such that the Pismo Formation sediments are exposed at the surface on the southern slopes of the Basin in this area. • Cross Section H-H' (Figure 4-20) extends approximately 2% miles through the Edna Valley. Land surface is approximately 350 feet on the northern end, sloping downward to about 230 feet near Corbett Canyon Road, then quickly rising to nearly 400 feet on the south end of the section on the upthrown side of the Edna Fault. The Paso Robles Formation is exposed at the surface for nearly the entire section. The section line crosses a small exposure of Recent Alluvium associated with Corral de Piedras Creek. In the northern half of the section, the Paso Robles Formation sediments are deposited directly on the basement rock formations, with a maximum thickness of about 80 feet. In the southern half of the section, the basement rock elevation plunges and the thickness of the Paso Robles Formation is about 150 to 230 feet. The Pismo Formation underlies the Paso 9.1 Page 137 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Robles Formation sediments in the southern half of the section, with a maximum thickness of about 200 feet. In the Corbett Canyon area, the section crosses the Edna Fault; south of the fault the basement rock formations are thrust up to the surface, and represent the boundary of the Basin. Cross Section I -I' (Figure 4-21) crosses the southern extent of the Edna Valley. The northern part of the section lies along the lower slopes of the Santa Lucia Range, and displays Paso Robles Formation sediments deposited on top of bedrock formations. A small pod of Recent Alluvium associated with Corral de Piedras Creek is displayed. Along the center of the Edna Valley, the Paso Robles Formation thickness is about 200 feet, and is underlain by about 100 feet of Pismo Formation sediments. The section crosses the Edna Fault Zone, which shows Pismo Formation sediments upthrown to land surface on the south side of one fault splay, and bedrock of the Monterey Formation upthrown to land surface elevation south of a second fault splay. 9*1 Page 138 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO e' �w A 2 ■ /Wee Of r � r 4f'C 71.4 M � f 1� +I Basin Setting (§ 354.14) C1 Explanation • Litholagic Data Point �f Cross Section Line A ,y �_ - Now - ► r 0 Bulletin 118 Basin Boundary City Boundary _ r►_ �' � /�/ Major Road Irf�� �~ Watercourse '1 01, •� Waterbody Am .. , dw E' TANK FA r.A9 RL7 r • ix� y, f� tom_ Y w ,dri r fj�r �t f r. ■ A4 �r r_ ! % �%c f ,. /r fir- r- rir..yrr i��,r i r PISM '! +►Jj wy �� + B E ACH Prepared for: qWA�[hcc =C L1a[c. 11'25.C'01 SAN LUIS OBISPO VALLEY BASIN GSP i CZ SAN`LUIS O-B`I_S`.P ❑ ❑' ■ ro � • F r� +r. • r f N References: AA 1 C", dinata: SyWII, NAD 1 D33 S'atoPlene Calf Diu V FIFE D105 Fcct 0.5 1 Project on'Lamhert C,nrn-ira Conic girl ilex Datum: hoith P.rrer can 1a-d5 25an -,is Cbisp C-nry 0 0 dx 0 d5 17 3 USGE � <i nr,Ppr, Lithologic Data Points and Cross Section Lines Figure 4-9 50 Page 139 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO D Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand 1a Paso Robles ❑ Fill ❑ Sandstone ❑ Sand Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments Perforated ❑ Silt ❑ Shale 47 Q] t Up w a � m � Prepared for: Vertical Exaggeration 11`1%� Author: NP 30X Oars: 10/4112019 SAN LUIS OBISPO VALLEYSASIN GSA 5001) 10Wo IWOU Distance in Feet 20NO 25000 A2 SOUTHEAST m — � 150 ,n 100 — 0 67 3 0 C 50 m 3 3 n D m -50 — -150 — 3000f1 Cross Section Al-A2 Figure 4-10 51 Page 140 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO A2 NORTHWEST r— 300 150 100 104 -200 Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand Paso Robles 0 Fill 0 Sandstone 0 Sand Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel 0 Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments Perforated ❑ Silt ❑ shale 0 5000 10000 150pu Diatanca in Feet Prepared For: Vertical Exaggeration Au[hor MP Q 2Lx 144 Darn. 10141Yd719 SAN LUIS OBISPO VALLEY BASIN GSP -G' A3 SOUTHEAST 250 — 200 15D — 10 — 50 — 0 -50 — -1D0 -150 — -200 �nnrra A Cross Section A2-A3 Figure 4-11 52 Page 141 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO A3 NORTHWEST 450 40C — 35C — Mc z� m sn S � — x � lei 153 -200 -350 _400 -4G0 Prepared For: Vertical Exaggeration "14�4 Author NP G 20X fiats. 1 N311209 9 SAN LUIS OBISPO VALLEY BASIN GSP Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand 14 Paso Robles ❑ Pill 0 Sandstone ❑ Sand JU Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments Perforated ❑ Silt ❑ Shale a SD0. room IaNO 20000 250R ]LLDC 03.. r—M Feat A4 SOUTHEAST 450 400 35@ �w 260 Poo 1R� 1a5i a Y 3 -150 -200 -300 _ -350 • QtY 411. Cross Section A3-A4 Figure 4A2 53 Page 142 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand ?q Paso Robles ❑ Fill ❑ Sandstone ❑ Sand o Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel A2 F Bedrock ❑ Gravel E] Serpentine G ® With Shell Fragments A3 H Perforated ❑ Silt ❑ Shale I A•1 e 8' NORTH 240 C 0 N _ SOUTH 240 — 2D N N — - - Pi15 — m io H n Poo — ISO - '? d J J 160 180 ALLUVIUM I80 _ 140 1 120 ~ 140 — 120 m m � _ PASO R48�-E5too _ L ` I ju s � �I — — � CI — li0 w _ �I J BO — F - F 40 N 20 V c0 20 I G - N I g BEDROCK _ 0 _ SI -20 — -20 f_ — w -40' -4a — m �p 'Patel Well and PelfW UjAh peprtl Is¢91)`BM 0 2500 F001; meta: Veell and r rfc; anon Dept- is 4' Y BGS JIM .60 I I O istancv in PovS � 9 Prepared For: Vertical Exaggeration Author NP 20X Darn. iC14112019 SAN LUIS OBISPO VALLEYSASIN GSA Cross Section 13-6' Figure 4-13 54 Page 143 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Explanation B Alluvium El Clay ❑ Rack El Silty Sand Al 7l v ?q Paso Robles ❑ Fill ❑ Sandstone ❑ Sand o E Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel A2 F Bedrock ❑ Gravel E] Serpentine ® With Shell Fragments A3 H Perforated ❑ Silt ❑ shale I RBI C1 C1' NORTH uet wwu _Goo Z�Oeo 260w SOUTH 6i L � 300 - ` - - pl � S 60 300 - —250 - 2K — j li M m c 200 ao L 5C-- m — m I3C 1w - 50 NI - PA59 ROBLES - �I 1 g � \ -- =1 PISM❑ Ui _ m _ I _ 'fetal Weusn� f+eeiotatiorr.4e�• 9 Prepared for: Vertical Exaggeration "IN Author: NP 35X Darn. 10/4112019 SAN LUIS OBISPO VALLEYSASIN GSA Cross Section CI-Cl' Figure 4.14 55 Page 144 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO I c C2 NORTH inn E0047492 250 200 150 — 1W Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand 5� Paso Robles ❑ Fill ❑ Sandstone ❑ Sand Pismo 0 Clayey Gravel 0 Clayey Sand ❑ Sand and Gravel Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments ■ PPrforatari 1771 Silt M ShalP Al B 0 ` Az F G H A3 I Al 0 25U0 5000 '90n I I I I I Distance in Faat Prepared for: Vertical Exaggeration qqjq� � Au[hor NP 20X Darn. 10/4112019 SAN LUIS OBISPO VALLEY SA SIN GSA C2' SOUTH 250 200 150 100 Cross Section C2-C2' Figure 4-15 56 Page 145 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand Paso Robles ❑ Fill ❑ Sandstone ❑ Sand Pismo ❑ Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel Bedrock ❑ Gravel E] Serpentine E] With Shell Fragments Perforated ❑ Silt ❑ shale LP 2F(,0 x5000 ?bon 100(k Distance in Feet Al A3 Dr SOUTH 1�0 140 — 12p — m — a 100 0 4 a m i m 3 � m 0 W 40 — 20 -20 — Prepared for: Vertical Exaggeration Cross Section D-D' 9111W sex h thar NF �.c. 131; zOt 9 SAN LUIS OBISPO VALLEY BASIN GSA Figure 4A6 57 Page 146 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Explanation 6 Alluvium ElClay ❑ Rack ❑ Silty Sand Al c] E NORTH Paso Robles 0 Fill 0 Sandstone 0 Sand o Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel nz F _ Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments 4. A3 H 220 Perforated ❑ Silt ❑ shale 2170 7 �[ R 7. o � q ti E❑2258Ba ,III ry N a ¢ m « m Er 1 _ N n SOUTH lnil c7 Q W 1C.0 — PASD ROBLES 140 — ALLUVIUM —� 14U 129 loe — PAS❑ ROBLES — fPISNI % re m m 'r — f — $ _ PIsM9 1 c 80 -N. a❑ m _ _ 3 v 1 t N u"7 40 .\ 4f.1 �. C �I 20 2Q U ,! BEDROCK o ❑ N 01 O N — I 8 — LLI 4n n ul - 0 — -SO o •Tafol Wcll and Peroration depth is440` BGS •l otaI Wcll and Pr<raration D7 pth u 2G0' BGS — -IIO 410 gUyJ U nuo 5oW 19pU IUWU S J s Distance in Feet Prepared for: Vertical Exaggeration qjjjN Au[hor NP 10 25X Da's: 10/4112019 SAN LUIS OBISPO VALLEY BASIN GSA Cross Section E-E' Figure 4A7 58 Page 147 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO F NCRT l— I 300 2V❑ L Prepared for: Vertical Exaggeration MW 0 1r : nuu�❑, tie ❑afo rnralir;I1 SAN LUIS OBISPO VALLEY BASIN GSP Basin Setting (§ 354.14) Explanation o Alluvium 0 Clay Flock 0 Silty Sand Paso Robles Fill Sandstone 0 Sand Pismo Clayey Gravel Clayey Sand Sand and Gravel Bedrock © Gravel 0 Serpentine With Shell Fragments Perforated D Silt Shale Edrta Fault F' ,: .,, .:.,,. SOUTH 30o- Cross Section F-F' Figure 4-18 59 Page 148 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO G _ NORTH 3n; 250 200 150 100 E — 0 i lo0 w -400 4W Prepared For: Vertical Exaggeratiah "IN Author NP lox Pars. 1 N31120r 9 SAN LUIS OBISPO VALLEY BASIN GSP Basin Setting (§ 354.14) d iston in Fcct Explanation Alluvium ❑ Clay ❑ Rack ❑ Silty Sand ?4 Paso Robles ❑ Fill 0 Sandstone ❑ Sand JU Pismo 0 Clayey Gravel 0 Clayey Sand ❑ Sand and Gravel d Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments Perforated ❑ Silt ❑ shale G' SOUTH 300 250 200 IW 5n 9 — � 50 — ao — _rx 20n — -25n� 35Q� 4MC ti 4q— Cross Section G-G' Figure 4.19 Page 149 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Explanation 6 Alluvium ❑ Clay ❑ Rack Al ce ❑ Silty Sand 14 Paso Robles ❑ Pill 0 Sandstone ❑ Sand o JU Pismo 0 Clayey Gravel ❑ Clayey Sand ❑ Sand and Gravel Az F Bedrock ❑ Gravel 0 Serpentine ® With Shell Fragments A3 Perforated ❑ Silt ❑ Shale A•1 H H' NORTH SOUTH 431C cc q U � n� ;• p C U (y y Lj R+' U� Vw \ —: 1 ALLUVIUM .uu PA50 Ra6Le9 - - e71, -- 2X — P18Mv cl w i Y $ F - - N I VI - 5) ° NI ` 8 � - vl I -10Q e — � F. u1 L7 r e lee m Mt.— in Feet 9 Prepared For: Vertical Exaggeration "IN Author NP "X L9ar�. 10/311209 9 SAN LUIS OBISPO VALLEY BASIN GSP Cross Section H-H' Figure 4-20 61 Page 150 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO I NORTH roc, sco 4�u •IGiI d 35i1 'v e v E a o - 0 ry 'y — ✓Eil w 1 Fil ]!i fl Basin Setting (§ 354.14) 0 2500 5000 7501) Distance in Feet Prepared For: Vertical Exaggeration 10X Darn. 10/3112019 SAN LUIS OBISPO VALLEY SASIN GSA Cross Section I -I' Figure 4-21 62 Page 151 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 4.5.2 Aquifer Characteristics Basin Setting (§ 354.14) The relative productivity of an aquifer can be expressed in terms of transmissivity, hydraulic conductivity, or specific capacity. The most robust method is measuring transmissivity using a long-term (frequently 24 hours or more) constant -rate pumping test. Water level drawdown data collected during this test can be analyzed and used to calculate transmissivity. Specific capacity is a simple measure of flow rate (gpm) divided by drawdown (feet), routinely measured by well service contractors during well maintenance and reported in units of gpm per foot of drawdown (gpm/ft). Specific capacity measurements may be affected by well construction details, and, therefore, are not only related to aquifer characteristics. Nevertheless, the following commonly accepted empirical relationships allows transmissivity to be estimated from specific capacity measurements. T (gpd/ft) = SC (gpm/ft) * (1,500 — 2,000), where T = Transmissivity (gpd/ft) SC = Specific Capacity (gpm/ft) 1500 — 2000 = Empirical factor, (1,500 used for unconfined, 2,000 for confined aquifer) Data describing these data from water wells throughout the Basin were compiled. The data was obtained from Previous regional studies or reports, previous pumping tests and well service information provided by local stakeholders. All available reports and documents that were made available through data requests, report reviews, etc., were reviewed for technical information, and included in this summary if the data were judged to be sufficient. DWR (1958) reports a range of irrigation well pumping rates from 300 to 600 gpm, and a range of specific capacity values of 15 to 20 gpm/ft for the Basin, corresponding to transmissivity estimates from 22,500 to 40,000 gallons per day per foot (gpd/ft). Boyle (1991) evaluated five constant -rate aquifer tests for City wells, all in the San Luis Valley, and reported transmissivity values ranging from 11,200 to 71,000 gpd/ft, with an average of 41,240 gpd/ft. DWR (1997) discussed the range of hydraulic conductivity values used in the preparation of its groundwater model, which averaged about 15 ft/day in the San Luis Obispo Creek Valley, and about 6 ft/day in the Edna area. Figure 4-22 displays the spatial distribution of the available data locations for well tests in the Basin. Inspection of Figure 4-22 indicates a good spatial coverage of locations, with reasonable data density throughout the Basin. Table 4-1 presents a compilation of all constant rate aquifer test data compiled during the preparation of this GSP. Table 4-2 presents a compilation of the specific capacity data. This information is used in the groundwater model development, and in the technical work supporting preparation of the GSP for the Basin. Table 4-1 presents a data summary for the constant rate aquifer test that was available, including information on pumping rate, static and pumping water levels, screened intervals, total depth, and formations screened. It was not always readily apparent which formations are screened from the available data, and sometimes well screens may span more than one formation. If there is uncertainty regarding this designation, it is indicated with a question mark in Table 4-1. Calculated transmissivity values range from less than 1,000 gpd/ft to a maximum of 158,400 gpd/ft. (The highest reported transmissivity value of 158,400 gpd/ft is an outlier, and was likely influenced by recharge from a nearby stream. 63 Page 152 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) Table 4-2 presents all available information for the specific capacity well tests identified. Table 4-2 includes a transmissivity estimate based on the empirical relationship discussed previously. Data presented tables 4-1 and 4-2 indicate that wells screened in the Alluvium and Paso Robles Formation have transmissivities ranging from about 5,000 to 158,000 gallons per day per foot (gpd/ft), and averaging over 42,000 gpd/ft. Wells screened in Paso Robles and Pismo Formations have transmissivities ranging from less than 1,000 to about 40,000 gpd/ft, and average about 10,000 gpd/ft. Page 153 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 61 � P -IFrC GE N Basin Setting (§ 354.14) ,8 � 14 ss � ?2 s64 117 31 21 9 60 20 7 57 "f��� r '�►� �' Explanation 1 - 5: GSI Constant Rate Test 5 49: Constant Rate Test Data 15 50 - 77: Specific Capacity Data jf srl ,W Major Raad �y y d;r�'�� Watercourse Asp- B118 Basin Boundary J. PW.rF Vol erle df - �fkNK FARM PM* A. 59 � 2 13 Prepared for: References: N t CvordnaLambert C NAi) al C nialealene California V RIPS 0405 FeH 11�4 0Autnor. AS A 0 0.25 05 1 PToDatum N Lambert Cvn1 OW Conic Qete' 11l�$lp14 �M�� �'m: North Amerkan 1Pa9 2 San Luis Obispo Counry 0 0 425 0.85 1 7 SAN LUIS OBISPO VALLEY BASIN GSP . M'°r"-W. 0 P ?. Hydraulic Parameter Data Locations Figure 4-22 65 Page 154 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO Table 4-1- Sala Luis Obispo Valley GrouIndwater 6asiIn Water Well Pump Test Data Summary Label No, Date Drilled Pump Test Date Pumping pate (GPM) Static Water level (feet bgsj Pumping Water Levef Efeet bgs) Drawdown (feet) Specific Capadty [gprn/foot) Est. Transmissivity Igpd/foot) Screen Length (feet) Hydraulic Coodurtivfty (ft/day) Total Depth (feet) PerfaratioNi Formation S(Yeened 1 7/31/2017 60 74.3 133 58.7 1.02 2,880 -4,525 230 1,37 - 2,15 440 180-200; 240.380; 320-440 Pismo 8/8/2017 27 21 27.5 6.5 4.2 3,605 -4,620 58 Paso Robles 3 8/24/2017 55 15.58 78 62.42 0.9 1,227 -4,840 Paso Robles 4 11/21/2017 265 61.G 155.2 1 97.6 3,02 1,600 300 2.92-3.11 500 200-500 Pismo 5 1Z/412017 12/9/2017 37 132 144.9 123 2.87 5,692 - 9,678 200 3.3 - 6.5 300 90-290 Paso Robles/Fismo 6 2/7/2003 2/19-21/2003 350 75 39,5 .32.1 11 23,100 60 51-3 145 45-85; 115-135 Alluvium/Paso Roblm 7 V31/2003 216/2003 400-450 9.92 28,67 19,75 33.3 66,600 45 197.3 80 25-70 Alluvium/Paso Robles 8 2/10/2003 2/19/2003 250 5.5 28,92 23.42 9.3 18,600 30 823 70 3"0 Alluvium/Paso Robles 9 4/15/1.936 4/19.2111995 3.7 11.86 2336 115 032 1.87 15 1.7 70 52-67 Alluvium 10 1123 203.3 2/5-9/2013 135 46,78 114.41 67,63 2 3,992 60 8.9 80.2.00; 140-150 Paso Robles/Pismo 11 8/18/3992 5/31/1992 656 52.4 122.3 69.90 9.38 5,773 200 3.8 440 130-190; 290-430 Pismo/Bedrock 12 4/4/2001 5/9J2001 500 70 85 15 33.33 66,667 180 49.4 520 160-200; 370-510 Pismo/6ecirack 13 5/12-16/2014 149 253.25 295,1 36,95 4.35 8,7Q0 190 6.1 550 280-420; 490-540 Pismo/Obispo or Bedrock 14 6/15/1988 6/30/1998 135 70.5 25,9 5,4 25 50,000 20 333,3 8o 50-70 Alluvium/Paso ROLiles 15 7/12/19BB 7/15/1988 80 24 42 18 4A4 3,889 30 39.5 57 27-57 Alluvium 16 7/22/1998 7/26/1988 300 11.5 Incomplete Data 140 40-130 Alluvlum/Paso Robles 17 4/2o/1989 5/1G/19B9 250 11.5 53Z 4L8 5.98 15,000 70 ME; 140 GO-130 Alluvium/Pro Robles 18 7/27/1998 9/2/1988 95 22 59 37.0 2,57 5,135 7Q 9.8 180 55-125 AI{uvium/Paso Robles 19 7/25/198E 8/4/1988 70 24 27.3 3,3 21.21 42,424 20 282.8 48 28-08 Alluvium 20 10/6/1989 10/24/1989 375 10A2 33.58 23,16 16.19 21,300 95 29.9 175 60-120; 140-175 Paso Robles/Pismo 71 6/28/1989 7/6/1989 200 10.4 .38.5 28.1 7.17 23,120 60 46,9 175 50-90; 150-170 Alluvium/Paso Rabies 22 4/26/19S9 5/10/1989 900 11 39,3 28.3 31,90 53,604 8o 106.0 140 42-122 Alluvium/Paso Rable= 2.3 6/14/1989 500 20 47 27 18,52 37,037 60 7 Alluvlum 24 12/22/19ES 12/27/1999 50 11 31.2 20.2 2.49 4,950 15 44.0 53 33-48 Bedrock 25 4/18/1989 4/20/1989 100 14 26 12 8.33 16,667 10 222.2 44 34-44 Alluvium 26 7/1.8J1386 60 55 290 275 0.27 533 80 0.3 296 220.300 Bedrock 27 5/15/1989 80 9,92 31 21.08 3.80 Z6,400 20 176 49 29-49 Alluvium 28 4/22/1993 165 19.63 33,4 13,77 11.98 87,120 3D 387.2 65 30-60 Alluvium 29 10/10/1990 25 39.5 78,5 39 0.64 401) SO 0.67 145 60-140 Paso Robles 30 1/20/2011 20 46.5 272 225.s 0.09 177 140 0.169 300 160-300 Bedrock 31 6/26/1991 .100 20 58 38 2.63 24,000 40 80 140 99-130 Paso Robles 32 4/12/1494 90 53.46 120 66.54 1.35 2,640 85 J.141 170 85-170 Pismo 33 6126119E9 596 513 147 963 6.79 3,311 280 1577 4Q0 60-120; 160-360;.5 380-40D Paso Robles/13quire 34 6115/7007 35G 65.5 138 77-5 4.83 10,766 200-7 35 6/15/2007 300 37 5 134 96.5 3.11 7,401 170 36 6/9/1985 295 36.25 98.45 62.2 4.74 33,907 240 Paso Ro6fes/Pl5mo 37 2/10/1997 300 110.2(7) 131.3 21.7 14.15 39,600 2M 24 490 190 294; 350�30; 430-490 PISMP 38 8/6/2014 150 166 215 49 3.06 3,046 300 39 8/7/2614 158 171 219 48 3.29 3,627 310 40 12/12/2005 170 116 196 70 243 5,081 41 12/22/2005 350 39.5 82 42.4 8.25 18,480 230 10.71 4307 200-430 42 6/29/2Q15 150 L1.8 226.1 94.3 139 10,850 ion 14A7 290 190.290 Pismo 43 6/30/1993 100 39.66 78,83 39,17 2.55 1,508 60 3.35 110 50-110 Paso Robles 44 7/21/1993 70 10.5 21.5 11 6.36 7,174 40 7.25 100 20-40; 8 0- 100 Paso Robles/Bedrock 45 3/25/2009 700 16.7 2193 142.6 1.40 3,105 700 2.07 400 130-170; 220-38t1 Pismo 46 4/3/2007 300 34.6 112.3 77.7 3.86 9,54: 260 4.89 480 270-480 Bedrock 47 4/9/2007 400 28.3 78 49.7 8.05 26,400 240 14.67 420 180.420 Pismo =I G 12/17/2015 150 114 266 152 0.99 851 -1,414 7 299 i Pismti 43 10/2812010 GOD 26.5 32.3 5.8 103.45 159,400 1 Alluvium/Paso Robles M.- Page 155 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO Table 4-2 - Sari Luis Obispo Valley Groundwater Basin Water Well Specific Capacity Data Summary Estimated Specific Capacity Static Water Pumping Water Diawdown Specific Capacity Duration Est Screen Length Hydraulic Label No. Pumping Rate (GPM) Transmissivity Depth Depth perforations Formation Screened Test Gate level {feet b gs level feet b gs) (feet) (gpm/foot) (hours) (feet ) Cnnductivit y Rftpd/footl (feet) eft/dayy 50 435 6-10 10,000-20,000 250? Paso Robles/Pismo 51 May 1999 12 10 24 14 0.86 4 1,714 30 Alluvium 52 2002 i8 19 63 44 0.41 12 818 86 Alluvlurn/Paso Robles 53 2003 3.5 16 42 26 p.13 72 269 80 Alluvfum/Paso Robles 54 7/18/1966 130 60 L17 20 4,333 30 19.3 90 60-90 Paso Robles 55 4/1511987 200 30 6.67 12 13,333 30 59.3 110 80-110 Paso Robles 56 12/22/1972 60 30 2 8 4,000 25 21.3 75 SO-75 Alluvfum 57 1980 24 110 0.22 8 436 SO 0.7 160 80-160 Bedrock 58 9/11/1991 15 13 1.15 8 2,308 40 7.7 90 50-90 Alluvium 59 9/12/1959 1.25 8 0.16 4 313 10 4.2 28 18-28 Alluvium GO 3/4/1957 45 18 2S 12 S,00O 17 39.2 37 20-37 Alluvium 61 3/15/1961 12 6 2 5 4,000 5 106.7 85 40-43; 75-77 Alluvium/Paso Robles 62 3/30/1956 8 4 2 2 4,000 15 35.6 32 17-32 Paso Robles 63 9/18/1989 5 20 0.25 1 Soo 10 6.7 50 40-50 Bedrock 64 8/29/1990 4 14 0.29 4 571 M 2.5 50 20-50 Alluvium 65 8/7/2014 47 206 257 51 0.92 1.5 1,843 340 Unknown 66 7/21/1993 75 2- 33 11 6.82 4 13,636 50 36.36 100 50-100 Bedrock 67 7/23/1993 69 11 16.25 5.25 13.14 4.5 26,286 55 63.72 100 25-65;85-100 Paso Robles/Bedrock G8 July 1993? ? 40 95? 4 120 60.120 Paso Robles 7/19/2012 83 45 87 4Z Z,O 69 5/19/2014 !04 82 123 41 2.5 Paso Robles/Pismo 4/24/2017 109 178 21.2 34 3.2 70 5/9/2014 94 is? 196 14 6.7 Paso Robles/Pismo 4/24/2017 124 85 117 32 3.9 71 4/24/2017 206 100 123 23 9.0 Paso Robles/Pismo 7/19/2012 320 98 101 3 106.7 72 5/19/14 367 133 183 50 7.3 Paso Robles/Pism❑ 4/24/17 483 104 141 37 13.1 12/5/12 93 86 101 15 5.2 73 5/19/14 55 140 65 12 4.6 Paso Robles/Pismo 4/24/17 81 SD 152 15 5.4 12/11/12 23 55 57 2 15. 5 -144 Paso Robles/Pismo 4/24/17 30 25 26 1 30.0 75 12/11/2012 17 62 66 4 4.7 Paso Robles/Pismo 12/5/2012 133 73 98 25 5.3 76 5/19/14 104 95 152 56 1.9 Paso Robles/Pismu 4124/17 127 89 126 37 3.4 12/5/2012 96 71 98 27 3.6 77 5/19/14 91 94 123 29 3.1 Paso Robles/Pismo 4/24/17 91 85 99 14 5.5 7/19/2012 193 107 135 28 6.5 34 5/19/14 169 86 132 46 3.7 Paso Robles/Pisrrio 4/24/17 259 75 135 60 4.3 33 4/24/2017 311 115 176 60 5.2 Paso Robles/Pismo 1 4/24/2017 65 29 49 20 3.3 Paso Robfes/Plsmo PTA Page 156 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 4.5.3 Aquitards Basin Setting (§ 354.14) An aquitard is a layer of low permeability, usually comprised of fine-grained materials such as clay or silt, which vertically separates adjacent layers of higher permeability formations that may serve as aquifers. Although there is some amount of clay present in nearly all of the boring logs reviewed for this plan, there are no formally defined or laterally continuous clay layers that function as aquitards within the Basin. In the San Luis Valley, wells are commonly screened across both the Recent Alluvium and the underlying Paso Robles Formation, and these two formations essentially function as a single hydrogeologic unit is this area. Similarly, in the Edna Valley, wells are commonly screened across both the Paso Robles Formation and the underlying Pismo Formation, and these two formations essentially function as a single hydrogeologic unit is this area. 4.6 SURFACE WATER BODIES Surface water/groundwater interactions represent a small, but significant, portion of the water budget of an aquifer system. In the Basin, these interactions occur primarily at streams and lakes. As previously discussed, there are several named creeks that flow across the Basin. In the San Luis Valley area of the Basin, these include San Luis Obispo Creek, Stenner Creek, Prefumo Creek, Froom Creek, and Davenport Creek, in addition to smaller unnamed tributaries. In the Edna Valley these include East and West Corral de Piedras Creeks (which join to form Pismo Creek just south of the Basin Boundary), and Canada de Verde Creek in southeastern Edna Valley. The watersheds support important habitat for native fish and wildlife, including the federally threatened South -Central California Coast steelhead (Oncorhynchus mykiss) (Stillwater Sciences et al. 2012, Stillwater Sciences 2014). Laguna Lake is the only lake in the Basin. It is a naturally occurring lake just north of Los Osos Valley Road and west of Highway 101. The downstream outlet of the lake flows into the Prefumo Creek culvert under Madonna Road. In the past, flashboards were used to maintain water elevation in the lake to support recreation and maintain wildlife habitat. However theseare no longer used.. The water in the lake is partially supplied by seasonal flow in Prefumo Creek, which flows into Laguna Lake. and at least partially supplied by subsurface groundwater inflow. Groundwater interaction with streams in the Basin is not well quantified, but it is recognized as an important component of recharge in the water budget. Where the water table is above the streambed and slopes toward the stream, the stream receives groundwater flow from the aquifer; this is known as a gaining reach (i.e., the stream gains flow as it moves through the reach). Where the water table is beneath the streambed and slopes away from the stream, the stream loses water to the aquifer; this is known as a losing reach. During seasonal dry flow conditions, it is clear that groundwater elevation is deeper than the streambed. Therefore, it is generally understood that the streams in the Basin discharge to the underlying aquifer, at least in the first part of the wet -weather flow season. If there is constant seasonal surface water flow, it is possible that groundwater elevations may rise to the point that they are higher than the stream elevation, and the creek may become a seasonally gaining stream in some reaches. Groundwater modeling can help evaluate surface water groundwater interaction.. The amount of flow in surface water/groundwater interaction is difficult to quantify. Boyle (1991) assumed that 10 percent of the measured surface water flow coming into the Basin in San Luis Obispo Creek and Stenner Creek was recharged to the aquifer, and used an average rate of 430 acre-feet/yr (AFY). In its draft Page 157 of 1183 SLO Basin Groundwater Sustainability Plan Basin Setting (§ 354.14) County of SLO and City of SLO report, DWR (1997) reports model -generated estimates ranging from streams gaining 2,700 AFY from the aquifer, to streams losing 680 AFY to the aquifer. The County, through its coordination with Zone 9 and the City, maintains a network of five stream gauges in the San Luis Valley Basin to record heights of flow throughout the year for flood warning purposes (Figure 3-10). The gauges were constructed in November 2001 and have periods of record from that year to the present. Continuous data monitoring of height of flow at the gages is recorded, but equivalent discharge (cubic feet per second) is not recorded. 4.7 SUBSIDENCE POTENTIAL Subsidence is the gradual settling or sinking of the earth's surface due to material movement at depth in a location, and is frequently associated with groundwater pumpage, and is one of the undesired results identified in SGMA. Subsidence has been documented in parts of the San Luis Valley. The most severe subsidence that has occurred in the Basin was in the 1990s along the Los Osos Valley Road corridor. Subsidence occurred within young organic soil (i.e., peat) in response to extraction of groundwater within a relatively shallow aquifer and resulted in significant settlement of the ground surface. The settlement caused local damage to businesses and homes in that area as local groundwater pumping dewatered the soft soil units beneath buildings and the surrounding area. Subsidence of more than 1 foot of settlement of the ground surface in some locations damaged buildings and resulted in reconstruction or retrofitting buildings. Another area of known subsidence is along the shores of Laguna Lake. Homes located along the shoreline have experienced settlement that has cracked foundations, patios, and window and door openings. Many homes in that area have been retrofitted to address the settlement. While the subsidence near Laguna Lake is not specifically related to extraction of groundwater, lowering of the groundwater table in that area could result in further settlement and subsidence. The historical manifestation of subsidence generally has been limited to a the area along Los Osos Valley Road and downstream, where compressible soil types that were particularly vulnerable to large settlements in response to lowering of the local groundwater table. This history emphasizes the importance of considering subsurface conditions that may be associated with subsidence. Not all soil and rocks are vulnerable to the type of subsidence that occurred along Los Osos Valley Road. The potential for subsidence to occur, and the severity of the subsidence, is dependent on the geology, groundwater levels, and the properties of the soil and rock that may be dewatered in association with groundwater pumping. The subsidence evaluation consisted of a review of published data and studies performed by local, state, and federal agencies, as well as a familiarity of local geology and soil. The following is a summary of the key findings. DWR identifies the Basin as having a low subsidence potential. However, historical subsidence is known to have occurred in specific geographic areas of the Basin because of groundwater pumping. The Basin was evaluated on the basis of the extent of known and mapped geologic units within the Basin (Yeh, 2018). The relative potential for subsidence was divided into three categories and delineated as shown in Figure 4-23. Category 1. Category 1 has the highest likelihood of future subsidence if subject to lowered groundwater levels in the future. Based on a review of public data and consultant reports, alluvium mapped in these areas contains young organic soil known in areas around Los Osos Valley Road, Laguna Lake, and low-lying wetland areas near Tank Farm Road. These areas are known to have experienced historical subsidence or to contain soft or organic soil and were identified as having a potential for subsidence in relation to geology and groundwater pumping. These areas are Page 158 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) identified as Category 1 in in Figure 4-23, with star symbols marking approximate areas of known historical subsidence. Extraction of groundwater resources in these areas could cause further subsidence. • Category 2. Low-lying topographic areas in the Basin that are mapped as young alluvial soil were identified as potentially containing soft or organic soil layers that may have a potential for subsidence in relation to groundwater pumping, but currently there is no historical or subsurface information to further evaluate those areas. Those areas are mostly located along Prefumo Creek and San Luis Obispo Creek and the main drainages through the west end of the Edna Valley near Price Canyon. These areas are identified as Category 2 in in Figure 4-23. This screening criteria recognizes the unconsolidated nature typical of young alluvium that has been mapped in these areas potentially could subside because of compaction of the aquifer if groundwater levels were lowered. • Category 3. Geographic areas in the Basin that were mapped as bedrock or older surficial sediments, and are not known to be underlain by young organic soil or young alluvium, were identified as Category 3 in in Figure 4-23. These areas were evaluated and characterized as not having factors known to be susceptible to subsidence in relation to groundwater pumping. Generally, these are upland areas where bedrock is shallow or where bedrock is mapped at the ground surface, such as in the areas around the airport and Orcutt Road (in Figure 4-23). 70 Page 159 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO t- 4 I MA SMAM , Basin Setting (§ 354.14) 21 [ t . i • ;6.! .,. r 107 1ANKFARM RD F 4 Explanation y Area of Historical Subsidence Major Road Watercourse Q Bulletin 118 Basin Boundary Expected Subsidence with Groundwater Removal Potential Subsidence with Groundwater Removal Low Risk of Subsidence r • - . � a ^I F F � w is r Alir- • t` ,a • - - M l 7 r - I - � _ • � � A •� L x r r' Prepared for: w' References: 1 Y t CPTopectionaie SYHem NAB pi C Stateviane Catifarnia V RIPS 0405 Feer 1364 aAuthor. AS a 0.25 0.5 1 Dat-nn ion Lambert Cvn19W conic pate' 11l25l7014 Miles OaNm. North American 1989 2 San Luis Obispo County 0 0425 0.85 17 3 %,g1one20z SAN LUIS OBISPO VALLEY BASIN GSP . �IObnnetem Subsidence Potential Figure 4-23 71 Page 160 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Basin Setting (§ 354.14) 72 Page 161 of 1183 SLO Basin Groundwater5ustainability Plan References County of SLO and City of SLO 5 REFERENCES Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. City of San Luis Obispo. 2016.2015 Urban Water Management Plan. 2016. -. 2018. General Plan. 2018. -. 2015. Water Resources Status Report. 2015. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. -. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. -. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. -. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustain ability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study. September. 1994. 73 Page 162 of 1183 SLO Basin Groundwater Sustainability Plan References County of SLO and City of SLO GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. Hall, C.A. 1979. Geologic map of the San Luis Obispo — San Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. —. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.l.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. 74 Page 163 of 1183 Draft Groundwater Sustainability Plan Chapter 5 — Ground Water Conditions forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by �WS C WATER SYSTEMS CONSULTING, INC. Lsul CHG GEI Contants � Stillwater Sciences water5alutions,Inc. 3/1/2020 Page 164 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO TABLE OF CONTENTS Table of Contents Listof Figures................................................................................................................................................. i Tables........................................................................................................................................................... iv Appendices.................................................................................................................................................... v Listof Terms Used........................................................................................................................................ vi ExecutiveSummary....................................................................................................................................... 1 1 Introduction to the SLO Basin GSP......................................................................................................... 1.1 Purpose of the Groundwater Sustainability Plan............................................................................ 1.2 Description of SLO Basin................................................................................................................. 1.3 Basin Prioritization.......................................................................................................................... 2 Agency Information (§ 354.6)................................................................................................................ 2.1 Agencies Names and Mailing Addresses......................................................................................... 2.2 Agencies Organization and Management Structures..................................................................... 2.2.1 County of San Luis Obispo....................................................................................................... 2.2.2 City of San Luis Obispo............................................................................................................ 2.2.3 Other Participating Parties in the MOA.................................................................................. 2.2.3.1 Edna Valley Growers Mutual Water Company............................................................... 2.2.3.2 Varian Ranch Mutual Water Company........................................................................... 2.2.3.3 Edna Ranch Mutual Water Company.............................................................................. 2.2.3.4 Golden State Water Company........................................................................................ 2.3 Authority of Agencies...................................................................................................................... 2.3.1 Groundwater Sustainability Agencies..................................................................................... 2.3.1.1 County of San Luis Obispo............................................................................................... 2.3.1.2 City of San Luis Obispo.................................................................................................... 2.3.2 Memorandum of Agreement.................................................................................................. 2.3.3 Coordination Agreements....................................................................................................... 2.4 Contact information for Plan Manager........................................................................................... 3 Description of Plan Area (§ 354.8)......................................................................................................... 3.1 SLO Basin Introduction.................................................................................................................... 3.2 Adjudicated Areas........................................................................................................................... 3.3 Jurisdictional Areas......................................................................................................................... 3.3.1 Federal Jurisdictions................................................................................................................ 3.3.2 Tribal Jurisdiction.................................................................................................................... i Page 165 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.3.3 State Jurisdictions................................................................................................................... 3.3.4 County Jurisdictions................................................................................................................ 3.3.5 City and Local Jurisdictions..................................................................................................... 3.3.6 Special Districts....................................................................................................................... 3.4 Land Use.......................................................................................................................................... 3.4.1 Water Source Types................................................................................................................ 3.4.2 Water Use Sectors................................................................................................................... 3.5 Density of Wells.............................................................................................................................. 3.6 Existing Monitoring and Management Programs........................................................................... 3.6.1 Groundwater Monitoring........................................................................................................ 3.6.1.1 Groundwater Level Monitoring..................................................................................... 3.6.1.2 Groundwater Quality Monitoring.................................................................................. 3.6.1.3 Surface Water Monitoring.............................................................................................. 3.6.1.4 Climate Monitoring......................................................................................................... 3.6.2 Existing Management Plans.................................................................................................... 3.6.2.1 SLO Basin Characterization and Monitoring Well Installation ........................................ 3.6.2.2 San Luis Obispo County Master Water Report(2012).................................................... 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014)............. 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan (2016) ........................... 3.6.3 Existing Groundwater Regulatory Programs............................................................................ 3.6.3.1 Groundwater Export Ordinance (2015).......................................................................... 3.6.3.2 Well Ordinances, County and City.................................................................................. 3.6.3.3 Countywide Water Conservation Program Resolution 2015-288 (2015) ....................... 3.6.3.4 Agricultural Order R3-2017-002 (2017).......................................................................... 3.6.3.5 Water Quality Control Plan for the Central Coast Basins(2017).................................... 3.6.3.6 California DWR Well Standards (1991)........................................................................... 3.6.3.7 Requirements for New Wells(2017)............................................................................... 3.6.3.8 Title 22 Drinking Water Program(2018)......................................................................... 3.6.3.9 Waterway Management Plan — San Luis Obispo Creek Watershed (2003).................... 3.6.3.10 Incorporation Into GSP.................................................................................................... 3.6.3.11 Limits to Operational Flexibility...................................................................................... 3.7 Conjunctive Use Programs.............................................................................................................. 3.8 Land Use Plans................................................................................................................................ 3.8.1 City of San Luis Obispo General Plan...................................................................................... 3.8.2 County of San Luis Obispo General Plan................................................................................. ii Page 166 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.8.3 Los Ranchos/Edna Village Plan................................................................................................ 3.8.4 Plan Implementation Effects on Existing Land Use................................................................. 3.8.5 Plan Implementation Effects on Water Supply....................................................................... 3.8.6 Well Permitting....................................................................................................................... 3.8.7 Land Use Plans Outside of Basin............................................................................................. 3.9 Management Areas......................................................................................................................... 3.9.1 Reason for Creation................................................................................................................ 3.10 Additional GSP Elements, if Applicable........................................................................................... 4 Basin Setting (§ 354.14)......................................................................................................................... 4.1 Basin Topography and Boundaries................................................................................................. 4.2 Primary Users of Groundwater....................................................................................................... 4.3 Soils Infiltration Potential................................................................................................................ 4.4 Regional Geology............................................................................................................................ 4.4.1 Regional Geologic Structures.................................................................................................. 4.4.2 Geologic Formations within the Basin.................................................................................... 4.4.2.1 Alluvium.......................................................................................................................... 4.4.2.2 Paso Robles Formation................................................................................................... 4.4.2.3 Pismo Formation............................................................................................................. 4.4.3 Geologic Formations Surrounding the Basin.......................................................................... 4.4.3.1 Monterey Formation....................................................................................................... 4.4.3.2 Obispo Formation........................................................................................................... 4.4.3.3 Franciscan Assemblage................................................................................................... 4.5 Principal Aquifers and Aquitards.................................................................................................... 4.5.1 Cross Sections......................................................................................................................... 4.5.2 Aquifer Characteristics............................................................................................................ 4.5.3 Aquitards................................................................................................................................. 4.6 Surface Water Bodies...................................................................................................................... 4.7 Subsidence Potential....................................................................................................................... 5 Groundwater Conditions (§ 354.16).................................................................................................... 2 5.1 Groundwater Elevations and Intepretation.................................................................................. 2 5.1.1 Fall 1954 Groundwater Elevations........................................................................................ 2 5.1.2 Spring 1990 Groundwater Elevations................................................................................... 5 5.1.3 Modeled 1990s Groundwater Elevations............................................................................. 7 5.1.4 Spring 1997 Groundwater Elevations................................................................................... 7 5.1.5 Spring 2011 Groundwater Elevations................................................................................... 9 Page 167 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 5.1.6 Spring 2015 Groundwater Elevations.................................................................................11 5.1.7 Spring 2019 Groundwater Elevations.................................................................................13 5.1.8 Fall 2019 Groundwater Elevations...................................................................................... 15 5.1.9 Changes in Groundwater Elevation.................................................................................... 17 5.1.10 Vertical Groundwater Gradients......................................................................................... 21 5.2 Groundwater Elevation Hydrographs......................................................................................... 21 5.3 Groundwater Recharge and Discharge Areas............................................................................. 24 5.3.1 Groundwater Recharge Areas............................................................................................. 24 5.3.1.1 Infiltration of Precipitation......................................................................................... 24 5.3.1.2 Subsurface Inflow........................................................................................................28 5.3.1.3 Percolation of Streamflow.......................................................................................... 28 5.3.1.4 Anthropogenic Recharge............................................................................................ 28 5.3.2 Groundwater Discharge Areas............................................................................................29 5.4 Change in Groundwater Storage................................................................................................. 29 5.5 Seawater Intrusion......................................................................................................................29 5.6 Subsidence.................................................................................................................................. 29 5.7 Interconnected Surface Water....................................................................................................30 5.7.1 Depletion of Interconnected Surface Water.......................................................................30 5.8 Potential groundwater dependent ecosystems.......................................................................... 30 5.8.1 Hydrology............................................................................................................................31 5.8.1.1 Overview of GDE Relevant Surface and Groundwater Hydrology..............................31 5.8.1.2 Losing and Gaining Reaches........................................................................................ 32 5.8.2 Vegetation and Wetland Groundwater Dependent Ecosystem Identification ...................34 5.8.3 Identification of Special -Status Species and Sensitive Natural Communities Associates withGDE's.......................................................................................................................................... 36 5.9 Groundwater Quality Distribution and Trends...........................................................................37 5.9.1 Groundwater Quality Suitability for Drinking Water..........................................................37 5.9.2 Distribution and Concentrations of Point Sources of Groundwater Constituents .............37 5.9.3 Distribution and Concentrations of Diffuse or Natural Groundwater Constituents ........... 41 5.9.3.1 Total Dissolved Solids..................................................................................................41 5.9.3.2 Nitrate......................................................................................................................... 43 5.9.3.3 Arsenic.........................................................................................................................45 5.9.3.4 Boron...........................................................................................................................47 5.9.3.5 Other Constituents...................................................................................................... 47 6 Water Budget (§ 354.18)........................................................................................................................ iv Page 168 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 6.1 Climate............................................................................................................................................ 6.1.1 Historical Climate.................................................................................................................... 6.1.2 Projected Climate.................................................................................................................... 6.2 Water Budget Data Sources and Groundwater Model................................................................... 6.3 Historical Water Budget.................................................................................................................. 6.3.1 Historical Time Period............................................................................................................. 6.3.2 Inflows..................................................................................................................................... 6.3.3 Outflows.................................................................................................................................. 6.3.4 Change in Storage................................................................................................................... 6.3.5 Sustainable Yield..................................................................................................................... 6.3.6 Quantification of Overdraft.................................................................................................... 6.4 Current Water Budget..................................................................................................................... 6.4.1 Inflows..................................................................................................................................... 6.4.2 Outflows.................................................................................................................................. 6.4.3 Change In Storage................................................................................................................... 6.4.4 Sustainable Yield..................................................................................................................... 6.4.5 Quantification of Overdraft.................................................................................................... 6.5 Projected Water Budget................................................................................................................. 6.5.1 Assumptions............................................................................................................................ 6.5.2 Inflows..................................................................................................................................... 6.5.3 Outflows.................................................................................................................................. 6.5.4 Change In Storage................................................................................................................... 7 Sustainable Management Criteria (§ 354.22-30)................................................................................... 7.1 Sustainability Goal........................................................................................................................... 7.2 Process for Establishing Sustainable Management Criteria........................................................... 7.2.1 Minimum Thresholds.............................................................................................................. 7.2.2 Measurable Objectives........................................................................................................... 7.2.3 Undesirable Results................................................................................................................. 7.3 Chronic Lowering of Groundwater Levels Sustainability Indicator ................................................. 7.3.1 Locally Defined Undesirable Results....................................................................................... 7.3.2 Minimum Thresholds and Measurable Objectives................................................................. 7.3.3 Relation to Other Sustainability Indicators............................................................................. 7.4 Change in Storage Sustainability Indicator..................................................................................... 7.4.1 Locally Defined Undesirable Results....................................................................................... 7.4.2 Minimum Thresholds.............................................................................................................. v Page 169 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 7.4.3 Measurable Objectives........................................................................................................... 7.4.4 Relation to Other Sustainability Indicators............................................................................. 7.5 Seawater Intrusion Sustainability Indicator.................................................................................... 7.5.1 Locally Defined Undesirable Results....................................................................................... 7.5.2 Minimum Thresholds.............................................................................................................. 7.5.3 Measurable Objectives........................................................................................................... 7.5.4 Relation to Other Sustainability Indicators............................................................................. 7.6 Degraded Water Quality Sustainability Indicator........................................................................... 7.6.1 Locally Defined Undesirable Results....................................................................................... 7.6.2 Minimum Thresholds.............................................................................................................. 7.6.3 Measurable Objectives........................................................................................................... 7.6.4 Relation to Other Sustainability Indicators............................................................................. 7.7 Subsidence Sustainability Indicator................................................................................................ 7.7.1 Locally Defined Undesirable Results....................................................................................... 7.7.2 Minimum Thresholds.............................................................................................................. 7.7.3 Measurable Objectives........................................................................................................... 7.7.4 Relation to Other Sustainability Indicators............................................................................. 7.8 Depletion of Interconnected Surface Water Sustainability Indicator ............................................. 7.8.1 Locally Defined Undesirable Results....................................................................................... 7.8.2 Minimum Thresholds.............................................................................................................. 7.8.3 Measurable Objectives........................................................................................................... 7.8.4 Relation to Other Sustainability Indicators............................................................................. 7.9 Management Areas......................................................................................................................... 7.9.1 Minimum Thresholds and Measurable Objectives................................................................. 7.9.2 Monitoring and Analysis......................................................................................................... 7.9.3 Explanation of How Operation of Management Area Will Avoid Undesirable Results.......... 8 Monitoring Networks (§ 354.34)............................................................................................................ 8.1 Monitoring Objectives.................................................................................................................... 8.2 Monitoring Network....................................................................................................................... 8.2.1 Chronic Lowering of Groundwater Levels............................................................................... 8.2.2 Reduction of Groundwater Storage........................................................................................ 8.2.3 Seawater Intrusion.................................................................................................................. 8.2.4 Groundwater Quality.............................................................................................................. 8.2.5 Land Subsidence...................................................................................................................... 8.2.6 Depletion of Interconnected Surface Water........................................................................... vi Page 170 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 8.3 Groundwater Monitoring Protocol................................................................................................. 8.4 Data Management System.............................................................................................................. 8.5 Assessment and Improvement of Monitoring Network................................................................. 8.6 Annual Reports................................................................................................................................ 8.7 Periodic Evaluation by Agency........................................................................................................ 9 Projects and Management Actions (§ 354.44)....................................................................................... 9.1 Projects........................................................................................................................................... 9.1.1 Project A.................................................................................................................................. 9.2 Management Actions...................................................................................................................... 9.2.1 Management Action A............................................................................................................ 9.3 Projects Needed to Mitigate Overdraft.......................................................................................... 10 Implementation Plan.............................................................................................................................. 10.1 Cost of Implementation.................................................................................................................. 10.2 Funding Alternatives....................................................................................................................... 10.3 Implementation Schedule............................................................................................................... 10.4 GSP Annual Reporting..................................................................................................................... 10.5 Periodic Evaluations of GSP............................................................................................................ 11 Notice and Communications (§ 354.10)................................................................................................. 11.1 Communications and Engagement Plan......................................................................................... 11.2 Nature of Consultations.................................................................................................................. 11.3 Public Meetings............................................................................................................................... 11.4 Incorporation of Feedback in Decision -Making Process................................................................. 11.5 Comments Received....................................................................................................................... 11.6 Responses to Comments................................................................................................................. 12 Interagency Agreements (§ 357.2-4)..................................................................................................... 12.1 Coordination Agreements............................................................................................................... 13 References.............................................................................................................................................. 14 Appendices The grey highlighted sections in the Table of Contents (TOC) indicate that the section has been previously released (Chapters 1 through 4) or will be released in the future (Chapters 6 through 14). The complete list of the anticipated TOC is presented to give the reader context as to how Chapter 5 — Groundwater Conditions, connects with the complete Groundwater Sustainability Plan. vii Page 171 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO LIST OF FIGURES List of Figures Figure 5-1: Groundwater Elevation Surface Fall 1954..................................................................................4 Figure 5-2: Groundwater Elevation Surface Spring 1990............................................................................. 6 Figure 5-3: Groundwater Elevation Surface Spring 1997.............................................................................8 Figure 5-4: Groundwater Elevation Surface Spring 2011...........................................................................10 Figure 5-5: Groundwater Elevation Surface Spring 2015...........................................................................12 Figure 5-6: Groundwater Elevation Surface Spring 2019...........................................................................14 Figure 5-7: Groundwater Elevation Surface Fall 2019................................................................................16 Figure 5-8: Change in Groundwater Elevation Spring 1997 to Spring 2011...............................................18 Figure 5-9: Change in Groundwater Elevation Spring 2011 to Spring 2015...............................................19 Figure 5-10: Change in Groundwater Elevation Spring 2015 to Spring 2019............................................. 20 Figure 5-11: Selected Hydrographs............................................................................................................. 23 Figure 5-12: Stillwater Percolation Zone Study Results.............................................................................. 26 Figure 5-13: Soil Agricultural Groundwater Banking Index Study Results .................................................. 27 Figure 5-14: Losing and Gaining Reaches Within the Basin........................................................................33 Figure 5-15: Potential Groundwater -Dependent Ecosystems(GDEs)........................................................35 Figure 5-16: Location of Potential Point Sources of Groundwater Conditions...........................................39 Figure 5-17: Distribution of TDS in Basin....................................................................................................42 Figure 5-18: Distribution of Nitrate in Basin...............................................................................................44 Figure 5-19: Distribution of Arsenic in Basin..............................................................................................46 viii Page 172 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Tables TABLES Table 5-1: Potential Point Sources of Groundwater Contamination..........................................................40 ix Page 173 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES Appendices Page 174 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level Xi Page 175 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant xii Page 176 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 177 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5 GROUNDWATER CONDITIONS (§ 354.16) This section describes the current and historical groundwater conditions in the Alluvial Aquifer, the Paso Robles Formation Aquifer, and the Pismo Formation Aquifer in the San Luis Obispo Valley Groundwater Basin. In accordance with the SGMA Emergency Regulations §354.16, current conditions are any conditions occurring after January 1, 2015. By implication, historical conditions are any conditions occurring prior to January 1, 2015. This Chapter focuses on information required by the GSP regulations and information that is important for developing an effective plan to achieve sustainability. The organization of Chapter 5 aligns with the six sustainability indicators specified in the GSP regulations, including: 1. Chronic lowering of groundwater elevations; 2. Groundwater storage reductions; 3. Seawater intrusion; 4. Land Subsidence; 5. Depletion of interconnected surface waters, and; 6. Degradation of groundwater quality. 5.1 GROUNDWATER ELEVATIONS AND INTEPRETATION As discussed in Chapter 4, information from available boring logs indicates that there is no regional or laterally extensive aquitard separating the Alluvial Aquifer, Paso Robles Formation aquifer, and Pismo Formation aquifer in the Basin. In the San Luis Valley, a physical distinction between Alluvium and Paso Robles Formation is often not apparent, and information from well completion reports in the Basin indicate that wells are regularly screened across productive strata in both formations, which effectively function as a single hydrogeologic unit. Likewise, in the Edna Valley, information from well completion reports indicates that wells are routinely screened across productive strata in both the Paso Robles Formation Aquifer and the Pismo Formation Aquifer, which effectively function as a single hydrogeologic unit. Boyle (1991) states that there is no strict boundary between the Alluvial Aquifer and the Paso Robles Formation Aquifer in the Buckley Road area. DWR (1997) states that all the sediments in the Subbasin are in hydraulic continuity. Because there is no available groundwater elevation data specific to the three individual aquifers, and because these formations appear to function as combined hydrogeologic units, groundwater elevation data are combined and presented as a single groundwater elevation map for each time period presented. In general, the primary direction of groundwater flow in the Basin is from the area of highest groundwater elevations in the Edna Valley northwestward toward San Luis Creek, where the flow leaves the Basin along the stream course. Groundwater in the northwestern areas of the Basin near the City of San Luis Obispo boundary and Los Osos Valley Road flows southeastward toward the San Luis Creek alluvium. In the southeastern portion of the Basin there are also local areas of flow discharging from the Basin along Pismo Creek tributaries of East and West Corral de Piedras Creek, and alluvium of other smaller tributaries further to the south. Groundwater Elevation maps for various recent and historical time periods are presented and discussed in the following sections. 5.1.1 Fall 1954 Groundwater Elevations DWR (1958) published a series of maps depicting groundwater elevations for various basins in the County, including groundwater elevations in the San Luis Obispo Valley Groundwater Basin for fall 1954 (Figure 5-1), Page 178 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO with contours based on field measurements of over 40 control points in the Basin. Groundwater flow direction arrows were added to Figure 5-1 to illustrate the primary direction of flow in the Basin. This is the oldest Basin -wide groundwater elevation data available. In the Los Osos Valley portion of the Basin, this map displays dominant groundwater flow direction from higher elevations in the in the northwestern extent of the Basin southeastward toward the discharge area where San Luis Creek leaves the Basin. The hydraulic gradient (the ratio of horizontal distance along the groundwater flow path to the change in elevation) in this area is approximately 0.004 feet/feet (ft/ft). In the Edna Valley portion of the Basin, the dominant groundwater flow direction is northwestward from the higher groundwater elevations in the southeastern part of the Basin (over 280 ft AMSL) to lower elevations (less than 110 feet AMSL) where San Luis Creek exits the Basin. The gradient across this area is steeper than in Los Osos Valley, approximately 0.009 ft/ft. This map also displays local areas of discharge coincident with the areas where San Luis Creek and Pismo Creek tributaries leave the Basin. Page 179 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO + Groundwater Conditions (§ 354.16) r ,A N IS 1�'j[ 1S V L U I S ' +-� ►- r 1- PL 1,41 k. 0 12 F IN I I -- I — a► # lm I, 4141 ! HI Ii EI WAN LVIS� 08ISP0 ae 1.0 BO.SIN x•f ,�. �2a►1 P 2 Eb 2��I • L U 0211111101 ISl� Bell f� D D • 2101 Prepared for: References: 1. Coordinate System: NAD al C StatePlane California V FPS O406 Feet Author: AB Projection: Lambert Conformal Conic Date: 11126/2019 0 0.25 0.5 1 Datum: Luis American 1983 104 a I Miles 2. San Luis Obsipo County Investigationm Slate Water Resources Board Bulletin No. 18, Place 98, May 1988. SAN LUIS OBISPO VALLEY BASIN GSP Explanation Groundwater Level Contour (10 feet) ♦ Groundwater Flow Direction 21p2 a 2twt 62 r„ fl RROY4 ARROW --= I GRAN - .00 • _ I , Groundwater Elevation Surface Fall 1954 Figure 5-1 11 Page 180 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.2 Spring 1990 Groundwater Elevations Boyle (1991) presents water level elevation contour maps for the spring of 1986 and 1990, based on water level data collected from 18 control points in the field. A digitized recreation of the Boyle groundwater elevation contours for spring of 1990 is presented in Figure 5-2 and displays patterns of groundwater flow direction in the Basin similar to those exhibited in the DWR 1954 map, although the flow gradient does not appear to be as steep as it is in the 1954 map. The year 1990 was in the midst of a significant period of drought in the Basin. The northwestward gradient across the central area of the Basin is approximately 0.006 ft/ft. Contours for the spring of 1986 are not re -presented in this report, but 1986 represents wetter conditions than the 1990 map, and it is noted in Boyle (1991) that there is a difference of approximately 10 feet of elevation between the two maps, representing the variation in water levels observed between wet and dry weather cycles in this time period. The contours in Figure 5-2 do not display an area of discharge where Corral de Piedras Creeks leave the Basin, but this is likely due to a lack of control points in this area. 5 Page 181 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Ar �_4 s �C<�yRo ve, , Tr -i Foon, C < 1• j —:'* � . ,� 1, �; �'"�,; f� �M Avila Beach l t. Prepared for: Author: Date: 1112/26l2019 SAN LUIS OBISPO VALLEY BASIN GSP P I S M O B E A C H SAN L\UIS OB IS,PO r BLIkley Rd eo 1 1 1 1 r-1 1 -,1 1 I ` 1 1 TANK FARM RD N References: 1. Coordinate System: NAD 1983 State Plane C,11,rnia V FIPS O405 Feet 0 0.25 0.5 1 Miles Projection: Lambert Conformal Conic Datum: North American 1983 A 2. San Luis Obispo County 0 0.425 0.85 1.7 3. ESRI �Klometem J tji f✓ V00 /7 0-r.. ,P-/ ,l.r 's �J :.A% 1 1 I I Notes: 1. Contours and flow direction were adapted from 1991 Boyle Groundwater Basin Evaluation, Plate 8. 2. Control points not displayed due to confidentiality agreements. Explanation ��... Approximate Water Level Contour' ♦ Approximate Flow Direction' C3 San Luis Obispo Valley Basin [:J City Boundary Major Road Watercourse Waterbody i I%f1z1ly a Groundwater Elevation Surface Spring 1990 Figure 5-2 ri Page 182 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.3 Modeled 1990s Groundwater Elevations In its draft report, DWR (1997) used a computer groundwater model to generate a series of modeled water level maps representing wet, dry, and average weather conditions. The model results are not re -presented in this GSP, but a review of the draft report indicates the maps display the same general flow direction patterns as the DWR (1958) and Boyle (1991) maps, which were based on data collected in the field. Water level elevations in the San Luis Valley in wet years were approximately 10 to 20 feet higher than in dry years. In the Edna Valley, the difference in groundwater elevations between wet and dry years was greater, approximately 20 to 30 feet. 5.1.4 Spring 1997 Groundwater Elevations More recent groundwater level data collected as a part of San Luis Obispo County's groundwater monitoring program were obtained and used to generate groundwater elevation maps to evaluate more recent conditions. The following assessment of groundwater elevation conditions is based primarily on data from the San Luis Obispo County Flood Control and Water Conservation District's (SLOFCWCD) groundwater monitoring program. Groundwater levels are measured through a network of public and private wells in the Basin. Figure 5-3 through Figure 5-7 presents the contours generated from the data for the Spring 1997, Spring 2011, Spring 2015, Spring 2019, and Fall 2019 monitoring events. The set of wells used in the groundwater elevation assessment were selected based on the following criteria: The wells have groundwater elevation data for the periods of record of interest; Groundwater elevation data were deemed representative of static conditions. Additional information on the monitoring network is provided in Chapter 8 — Monitoring Networks. Based on available data, the following information is presented in subsequent subsections. • Groundwater elevation contour maps for spring 1997, 2011, 2015, 2019, and Fall 2019; • A map depicting the change in groundwater elevation between 1997 and 2011; • A map depicting the change in groundwater elevation between 2011 and 2015; • A map depicting the change in groundwater elevation between 2015 and 2019; • Hydrographs for select wells with publicly available data. Figure 5-3 presents a groundwater surface map for Spring 1997 based on field data collected by the County (control points are not displayed to maintain confidentiality agreements negotiated with well owners). The southeast (near Lopez Lake) and northwest (Los Osos Valley) areas of the Basin had no wells monitored during these events to calculate water levels, so contours are not presented for those areas. Several features on this map are apparent. First, a pronounced groundwater mound is evident at the location where West Corral de Piedras Creek enters the Basin in Edna Valley, near the corner of Biddle Ranch Road and Orcutt Road; three control points are present in this area, providing reliable documentation for water levels in this vicinity. This indicates that this is a groundwater recharge area. The regional northwesterly flow direction apparent in the previously discussed water level maps is still evident here; the groundwater flow gradient is about 0.011 ft/ft, somewhat steeper than the Spring 1990 gradient presented by Boyle. 7 Page 183 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Prepared for: Author: AB Date: 11l2612019 SAN LUIS OBISPO VALLEY BASIN GSP Groundwater Conditions (§ 354.16) 411,111, P I S M O B E A C H S A N l I S OB IS.PO ;K IN 1 tJ j � o I f 1 1 TANK FARM RD N References: 1, Coordinate System: NAD 1983 State Plane California V FPS O401 Feet 0 0.25 0.5 1 Miles Projection: Lambert Conformal Conic Datum: North American 1983County A 2. San Luis Obispo County 0 0.425 0,85 1.7 3 ESRI � Kilometers N O 1 1 Note: 1. Control points not displayed dur to confidentiality agreements. Explanation �`.. Approximate Water Level Contour Approximate Flow Direction a San Luis Obispo Valley Basin [:J City Boundary Major Road Watercourse Waterbody I%f 1z� Vc r a° �o Grac a Groundwater Elevation Surface Spring 1997 Figure 5-3 Rl Page 184 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.5 Spring 2011 Groundwater Elevations Spring 2011 represents a time period just prior to the recent drought, but after the expansion of agricultural pumping in Edna Valley (discussed further in Chapter 6, Water Budget). As such, effects of the recent drought should not yet be apparent, but reduced groundwater levels due to expanded agricultural pumping should be evident. Figure 5-4 displays groundwater elevation contours for Spring 2011. The groundwater mound near Biddle Ranch Road and Orcutt Road is again evident, with a maximum groundwater elevation of over 320 feet. Groundwater flow direction appears to indicate areas of discharge from the Basin in Edna Valley along Corral de Piedras Creeks and Canada Verde Creek, and along San Luis Creek in San Luis Valley. The area near Edna Road and Biddle Ranch Road indicates a steep local gradient, likely associated with local pumping. The contour near the exit of Corral de Piedras Creeks is 180 feet. The gradient across the central Basin is almost identical to the Spring 1997 map, about 0.011 ft/ft. The gradient is much shallower in the San Luis Valley part of the Basin. Page 185 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 4. r > Explanation "`.• Approximate Water Level Contour Approximate Flow Direction Jf - an Luis I Valley Basin J �y+� . C3 S L Obispo e �MSunt 2� 1 City Boundary r1 � Major Road 4� ���j Watercourse CAP �' Waterbody 1 // 7 JILj a1 - �iFF S A N L U I S 1 ,f�` i�. -j., 1.WE vi 1%� ! 01 " 1 TANK FARM RE) o f % + a 1 0 t t c,ee�y A. r 0* Ali s `'�� . J tic, �% . �,� ► 46, Amrof w r+ �J Avila Beach Prepared for: Jok . a Author: AB Date:'I'll 2019 SAN LUIS OBISPO VALLEY BASIN GSP QJ to Ca(�%.•I� r i r f.. t a fan r ' r BEACH •,\., � w /� i f� N References: 1, Coordinate System: NAD 1983 StatePlane Cal'rfornia V FIPS O405 Feet 0 0.25 0.5 1 err Con formal Conic PaStum:ion: NorLamth American Datum: Northbispo ®Miles A County 2. San Luis Obispo County 0 0.425 0.85 1.7 3. ESRI ® Kilometers 1 ci ""a Ve. Note: 1. Control points not displayed dur to confidentiality agreements. r. si fi, 9„r ra Grande CIOV r✓' Groundwater Elevation Surface Spring 2011 Figure 5-4 10 Page 186 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.6 Spring 2015 Groundwater Elevations Figure 5-5 presents groundwater elevation contours for Spring 2015. Spring 2015 represents a time period in the midst of the recent drought, and after the expansion of agricultural pumping in Edna Valley. The effects of the drought are apparent upon close inspection of the contours in Figure 5-5. In the Edna Valley, the maximum contour of the recharge area near Orcutt Road and Biddle Ranch Road is 280 feet, about 40 feet lower than in the Spring 2011 map. The contours immediately west of the mound are still steep, but flatten out significantly along Davenport Creek, resulting in a much shallower gradient in this area than in the Spring 2011 map. Contours east of the mound along Orcutt Road are 20 to 40 feet lower than in the Spring 2011 map. In the San Luis Valley, a 100-foot contour is evident near the exit of San Luis Creek from the Basin, which is about 10 feet lower than the contour in the Spring 2011 map. 11 Page 187 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Ar i y_4 44 ♦ Y p O,/i � �� •ri � re• W5 I A f ' �M Avila Beach w+ Prepared for: 0 Author: A8 Date: 11126/2019 SAN LUIS OBISPO VALLEY BASIN GSP P I S M O B E A C H =M_ SAN L\UIS OB IS,PO 1 r 1 �--- �// 7IT. - a ?- TANK FARM RD N References: 1, Coordinate System: NAD 1983 State Plane C,11,rnia V FIPS O405 Feet 0 0.25 0.5 1 Miles ProjectionLambert Conformal Conic Datum: North American can1983 A 2. San Luis Obispo County 0 0.425 0.85 1.7 3. ESRI �Klometem � 1 / 1 o m o0 1 ,w C c Explanation Approximate Water Level Contour Approximate Flow Direction C3 San Luis Obispo Valley Basin C:J City Boundary Major Road Watercourse Waterbody &liB f if a ` JO i jPoo, C, yu GTapde a° / o Grate Note: 1. Control points not displayed dur to confidentiality agreements. a +d 1z1ly Groundwater Elevation Surface Spring 2015 Figure 5-5 12 Page 188 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.7 Spring 2019 Groundwater Elevations Figure 5-6 presents a groundwater surface elevation map for Spring 2019. Spring 2019 represents a time period at the end of seasonal winter rains, and after the end of the recent drought. Rebounds of groundwater elevations from the drought are apparent upon inspection of the contours. In the Edna Valley, the maximum contour of the recharge area near Orcutt Road and Biddle Ranch Road is 300 feet, about 20 feet higher than in the Spring 2015 map. Contours east of the mound are about 20 feet higher than in the Spring 2015 map. Contours along Davenport Creek are about 20 feet higher than in the Spring 2015 map. The elevation at Edna Road and Biddle Ranch Road is about 230 feet, over 50 feet higher than in the Spring 2015 map. 13 Page 189 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 1 49kW1 - .`0` I e 7 `I<(FyRO `� i ���"�sy�� A. p� ��/ % J % \• %� , •�\ S A N L U I S . ;X� �� rf ' �7 ��� r '[ ,/•' " l.ngunn Lnhe O B I SAP O !r/i � _ /, � �►� "\" `\ ,�/ice >� '"� • ^- /' +i "j• , s _ � �r7M,� ••\, 'rem. .'�, �� "V f ft/ ,� •\ %I• ram_'' 101 ♦ r---_-,-_-- ti TANK FARM RD •\ `, t'- % e too "'4 J '�j. �/' t goo,3+� / > 1 1 It It 1 10. � f'T '50��i-`�=r �►',� 1 �► l�r� ^ �y 'I On_enp°t 1 ♦ rI+ «low-P�e J Cat, O d cl Avila Beach 7► , °n F� » s ` II •`,f •�� ^ I \ a � c e �'� ems. �..�. Jr,, P,rc�rlc:oce.0 P I S M O`er `` ,•\ �/, �i rl ram-.. ` r Prepared for: Author: AB Dare: 11/28/2019 SAN LUIS OBISPO VALLEY BASIN GSP N References: 1. Coordinate System: NAD 1983 State Plane C,11,rnia V FIPS O405 Feet 0 0.25 0.5 1 Miles Conformal Conic Projection North ALammerican Datum: North American 1983 A my 2. San Luis Obispo County 0 0.425 0.85 1.7 3. ESRI �Klometem �" t78591f �y" } it _ +t./ p/{,•s�•f/�f��I 4% 'L //C ti y Note: 1. Control points not displayed dur to confidentiality agreements. Explanation �`.. Approximate Water Level Contour ♦ Approximate Flow Direction Gj San Luis Obispo Valley Basin J City Boundary Major Road Watercourse Waterbody 1 "'apde CreeW ,/ 0 / Ao Ot �tl►.J �' !a Groundwater Elevation Surface Spring 2019 Figure 5-6 14 Page 190 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.8 Fall 2019 Groundwater Elevations Figure 5-7 presents a groundwater surface elevation map for Fall of 2019. This time period represents recent conditions at the end of the summer dry season for comparison against the spring conditions. Overall, the contours indicate lower groundwater levels than those displayed in the Spring 2019 map. Groundwater contours east of the recharge mound at West Corral de Piedras are about 20 feet lower than the Spring 2019 map. The groundwater elevation at Edna Road and Biddle Ranch Road is about 220 feet, approximately 10-20 feet lower than in the Spring 2018 map. 15 Page 191 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Explanation AF ��f✓ :�� , , / �`.. Approximate Water Level Contour -,. �, � i, ice.- ����� �` 1-t„�► � Approximate Flow Direction /* �enf ' M � San Luis Obispo Valley Basin d Ri r N/ er [-i City Boundary A '----- / J.,j t� [ Major Road +►�> L j� '� /Y,�id� Watercourse Or y40 SOs° j� s 1� —' — / �� Waterbody spa<��Ro c`1� •.y ��(l - � • � r ✓ \ w w LuIS ''� /f, AV I 1 '�� �.'I• i�-A. r .f /•' l.ngunn Lnhe O B I S,P O r ♦� / •/ 'J /��r �fir'--1�'"ek �7 �� e. � � r� � `-I i✓ r r ;r j3 eek ♦ J ,' `,� ,.all► '`\• ' � '°`- .o `�' ,� ♦ '\ � // / _ I `,! ✓ +� f l '� /• \• 101 ,♦♦ R------- 1 TANK FARM RD ` 1 f� 'Y •.. �I / l r ''/ •` ' r / '! 1, , •fie ----- too 281 Ir -04 011, 44 i 0 Ci r; -Y/��,1 fl�� •/_ ��� / , °rw; - , �HRO�r 2a0 / v -//•L &d� ♦♦ ♦� n vu ip04eRPNG aec-`c� rr-' sec+`e ✓r j, AP.4NZ.I me + �♦ degc r� 4 a _ ���f M r � r� � 1 9 n ' I% «• C- -�' r. `♦� ♦♦ ♦; - -- All 41 ?, �Arti /ram''( - ' 4 1 ,aAir �_- y- -�'- ! •hy 5ar "5 -�1f¢ C8�1„ ^�•w,/�' , `♦ r°a�U �� - ��' Am— iz r /y444 r { w r Avila Beach �7► + F , "r!' _ �, o�ool 11AC11-�Lc � R r . P I S M O its Prepared for: Al References: 0I V 1, Coordinate System: NAD 1983 State Plane California V RIPS 0405 Feet Author: A8 0 0.25 0.5 1 Projection: Lambert Conformal Conlc Date: 11/28l2019 Miles Datum: North American 1983 2. San Luis Obispo County Mk 0 0.425 0.85 1.7 3. ESRI SAN LUIS OBISPO VALLEY BASIN GSP Kilometers �;I �iIIaat T" .'appe CreeW / �Arr yu GT I , 0 as r ' / • . / oho Or !a Note: 1. Control points not displayed dur to confidentiality agreements. Groundwater Elevation Surface Fall 2019 Figure 5-7 16 Page 192 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.9 Changes in Groundwater Elevation In order to demonstrate how groundwater elevations have varied over the recent history of the Basin, a series of maps were generated that display changes in groundwater elevation. These maps were developed by comparing groundwater elevations from one year to the next and calculating the differences in elevation over the specified time period. It should be noted that the results of this analysis are largely dependent on the density of data points, and should be viewed as indicative of general trends, not necessarily as accurate in specific areas where little data is available. The first time period selected compares changes in groundwater elevation from 1997 through 2011. The year 1997 was selected as a starting point because it is assumed to represent conditions prior to the significant expansion of agricultural groundwater pumping in the Basin. The year 2011 was selected as the end point because it represents conditions prior the start of the recent drought. Calculated changes in groundwater elevation over this 14-year period are presented in Figure 5-8. This figure indicates a maximum decline in groundwater elevation of over 60 feet in the Edna Valley, southeast of East Corral de Piedras Creek between Orcutt Road and Corbett Canyon Road. The calculated groundwater elevation shows declining groundwater levels to the northwest of this location. No significant declines are indicated northwest of Biddle Ranch Road over this time period. The next time period selected compares changes in groundwater elevation from 2011 through 2015. This time period was selected to capture the start of the drought to a point four years into the drought, thereby capturing the period of greatest groundwater elevation change. Calculated changes in groundwater elevation over this 4-year period are presented in Figure 5-9. This figure indicates a maximum decline in groundwater elevation of over 80 feet located in the Edna Valley, near the intersection of Edna Road and Biddle Ranch Road. The calculated reductions in groundwater elevation decline in all directions from this location. No significant declines are indicated in the San Luis Creek Valley portion of the Basin over this time period. The next time period selected compares changes in groundwater elevation from 2015 through 2019. This time period was selected to capture the potential recovery of the Basin following the drought. Calculated changes in groundwater elevation over this 3-year period are presented in Figure 5-10. Groundwater elevations are shown to have rebounded throughout the entire area in which data was available. The greatest increase in groundwater elevation is coincident with the area of greatest declines from 2011-2015, near the intersection of Edna Road and Biddle Ranch Road. 17 Page 193 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) J "ems i R�F�R J 101 S A N LNUIS 0BIS.PO /' r �'� •may - �� � ~ � � - - -Try► . f .1 r ><r ' PACIFIC O C E A.:\ B E A C H .`\�-' Prepared for: A' References: Author AB 10 Date. 2128/2020 IA V a o. ze o.5 � Miles 1- Coortli, La System NAO al C StatePlane Caltlornia V FIRS 0405 Feet Projed,or,. Lambert Conformal Conic Datum. North American 1983 2 Sr,. Luis Obispo County 0 0.425 0,85 1,7 3-USGS SAN LUIS OBISPO VALLEY BASIN GSP �IUI°mwrs I .. A oil. � e AL 1. Explanation — — Bedrock Divide Q San Luis Obispo Valley Basin Water Level Change Spring 1997 to Spring 2011 Q a -60 feet Q -80 to -50 feet -50 to -40 feet 0 -40 to -30 feet -30 to -20 feet -20 to -10 feet Q -10 to 0 feet 0 > 10 feet All Other Features J City Boundary N Major Road ^ Watercourse 1: Waterbody ,� Gra°de 0 'V Change in Groundwater Elevation Spring 1997 to Spring 2011 Figure 5-8 18 Page 194 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 4 Oil ' PACIFIC O C E ^ A. :\ PISMO B E A C H \^` .\wH.a7 --%/.► r%Y Prepared for: A' References: Auch°r AB Date. 2128/2020 IlV ,4 a o.ze o.5 1 Miles 7_ Cooron La System. NA 1 B83 SfatePlane Galilornia V FIP50405 Feet Dr°jedi°r,. Lambert 1 a3 cor,i° Datum. North American 1983 2- San Luis Obispo County 0 0.425 0,85 N 1,7 3- 1 SAN LUIS OBISPO VALLEY BASIN GSP �Kil°meters � P Will �� 4J •'J ate' 01, J Explanation — — Bedrock Divide 0 San Luis Obispo Valley Basin Water Level Change Spring 2011 to Spring 2015 0 < -60 feet -60 to -50 feet Q -50 to -40 feet 0 -40 to -30 feet Q -30 to -20 feet 0 -20 to -10 feet Q -10 to 0 feet > 10 feet All Other Features J City Boundary Major Road Watercourse Waterbody f Catill, ' - ' � r Change in Groundwater Elevation Spring 2011 to Spring 2015 Figure 5-9 19 Page 195 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) S A IN L u I S O B I S P O TANK I- F� Z Ile ril L y/ 7`ii, ,ti• , ` � r / /'fir .� ` �, ov 9V10 �1 Will 4P mw At Pa CIFLC OCEAiN 1 PISMO B E A C H Prepared for: Author: Date: 11f2l26/2019 SAN LUIS OBISPO VALLEY BASIN GSP N References: 1. Coordinate System: NAD 1983 State Plane Calrfornia V FIPS O4. Feet 0 0.25 0.5 1 Miles Pro jection: Lambert Conformal Conic Datum: North American 1983County A 2. San Luis Obispo County 0 0.425 0,85 1.7 3. USGS � Kilometers , . �14 y y e 01 oi/4 000 . oll r��iR 6 I. Explanation — — Bedrock Divide Q San Luis Obispo Valley Basin Water Level Change Spring 2015 to Spring 2019 0 < 0 feet 0 0 to 10 feet 0 10 to 20 feet 0 20 to 30 feet 0 30 to 40 feet 0 > 40 feet All Other Features [_J City Boundary Major Road Watercourse Waterbody f JA ' 1 � /A'r°ya.GaNle f 1 1 Change in Groundwater Elevation Spring 2015 to Spring 2019 Figure 5-10 20 Page 196 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.1.10 Vertical Groundwater Gradients Vertical groundwater gradients are calculated by measuring the difference in head at a single location between specific and distinct strata or aquifers. The characterization of vertical gradients may have implications with respect to characterization of flow between aquifers, migration of contaminant plumes, and other technical details describing groundwater flow in specific areas. In order to accurately characterize vertical groundwater gradient, it is necessary to have two (or more) piezometers sited at the same location, with each piezometer screened across a unique interval that does not overlap with the screened interval of the other piezometers(s). If heads at one such piezometer are higher than the other(s), the vertical flow direction can be established, since groundwater flows from areas of higher heads to areas of lower heads. However, because such a "well cluster" must be specifically designed and installed as part of a broader investigation, limited data exists to assess vertical groundwater gradients. Previous hydrologic studies of the Basin (Boyle 1991, DWR 1997) indicate that groundwater elevations are generally higher in the Alluvial Aquifer than the underlying Paso Robles Formation Aquifer, resulting in groundwater flow from the Alluvial Aquifer to the underlying Paso Robles Formation aquifer (although this may change seasonally). The lack of nested or clustered piezometers to assess vertical gradients in the Basin is a data gap that will be discussed further in Chapter 8. There are no paired wells that provide specific data comparing water levels in wells screening the bedrock and the Basin sediments. However, from a conceptual standpoint, the Monterey Formation is assumed to receive rainfall recharge in the surrounding mountains at higher elevations than the Basin sediments. For this reason, it is assumed that an upward vertical flow gradient exists between the bedrock and the overlying Basin sediments. Because the bedrock formations are significantly less productive than the Basin sediments, the rate of this flux is not expected to be significant. 5.2 GROUNDWATER ELEVATION HYDROGRAPHS The San Luis Valley and the Edna Valley are characterized by different patterns of groundwater use. In the San Luis Valley, groundwater use has been dominated by municipal and industrial use, with total groundwater use decreasing since the 1990s, as the City has diversified its surface water supplies, and placed most of its wells on standby status. During this time several in -City agricultural operations have also been developed into housing and commercial districts and now rely on the City's surface water supplies in place of groundwater pumping. In the Edna Valley, groundwater use is dominated by agricultural use, with total use increasing since the 1990s. During the past 15 to 20 years, wine grapes have supplanted other crop types (such as pasture grass and row crops) as the dominant agricultural use within the Edna Valley. Available water level data was reviewed, and data from wells with the longest period of record are presented in Figure 5-11, and discussed in this section. Most of the data was obtained from the County's groundwater monitoring network database. Figure 5-11 presents groundwater elevation hydrographs for the ten wells throughout the Basin with the longest period of record. State well identification numbers are not displayed for reasons of owner confidentiality. Appendix 5A presents depth to water hydrographs for all wells for which the county had water level data. Three distinct patterns are evident in different areas of the Basin and are discussed below. The hydrographs for the wells in the San Luis Valley indicate that water levels in these wells, although somewhat variable in response to seasonal weather patterns, water use fluctuations, and longer -term dry weather periods, are essentially stable. There are no long-term trends indicating steadily declining or 21 Page 197 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO increasing water levels in this area. The wells along Los Osos Valley Road (hydrographs 1 and 2 on Figure 5-11) display fluctuations within a range of less than 20 feet over a period of record from the late 1950s to the mid-1990s. This period includes the drought of the late 1980s to early 1990s. The well just west of the intersection of Tank Farm Road and Orcutt Road (hydrograph 4 in Figure 5-11) displays a similar pattern, with water level variations within a range of about 10 feet from 1965 to 2013. The wells in the vicinity of Highway 101 and Los Osos Valley Road (hydrograph 3 in Figure 5-11) also display water levels in relative equilibrium, with the exception of the early 1990s, when drought -related pumping and weather patterns resulted in noticeable declines in the water level in this well. These water levels recovered to their pre - drought levels by the mid-1990s. The long-term stability of groundwater elevations in these hydrographs indicates that groundwater extractions and natural discharge in the areas of these wells are in approximate equilibrium with natural recharge and subsurface capture, and that no trends of decreasing groundwater storage are evident. A second distinct pattern is evident in hydrographs from wells in the area immediately east of the intersection of Biddle Ranch Road and Orcutt Road, where West Corral de Piedras Creek enters the Basin (hydrographs 5 and 6 in Figure 5-11). The hydrographs of the two wells in this area display much greater volatility in response to seasonal and drought cycle fluctuations than the wells in San Luis Valley, with water levels fluctuating within a range of over 40 feet, as opposed to the range of 10 to 20 feet in the San Luis Valley wells. However, water levels appear to rebound to pre -drought levels when each drought cycle ends. Groundwater elevations displayed in these two hydrographs do not display a long-term decline of water levels. This pattern is likely associated with local recharge of the aquifer derived from percolation of stream water in West Corral de Piedras Creek as it leaves the mountains and enters the Basin. By contrast, several wells in the Edna Valley display steadily declining water levels during the past 15 to 20 years. Hydrographs for four wells (hydrographs 7, 8, 9, and 10 on Figure 5-11) in the Edna Valley display groundwater elevation declines of about 60 to 100 feet since the year 2000. Groundwater elevations in the Edna Valley displayed the largest historical declines in the Basin. This hydrograph pattern indicates that a reduction of groundwater storage has occurred over this period of record in the area defined by these well locations. It is understood, and will be discussed in greater detail in Chapter 6 (Water Budget), that agricultural pumping has increased in Edna Valley during this time period, likely explaining the patterns of declining groundwater elevations in these hydrographs. 22 Page 198 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 180 160 —y 140 120 100 80 60 40 1950 1960 1970 2980 1990 2000 2010 2020 200 c � 180 160 140 ;1z0 '- 100 So 60 1950 1960 1970 2980 1990 2000 2010 2020 Alit Jw 270 ` 250 f � 230 g 210 190 ! �z r�� # 170 150 7 �. 130 L N 1950 1960 1970 2980 2990 2000 2010 2020 220 200 ::180 160 140 120 8 100 so 1950 1960 1970 1980 1990 2000 2010 2020 1�w Groundwater Conditions (§ 354.16) ` —~�� ' • -, tom �-s Flrnlannfinn s ISO 160 140 d 120 0 $100 so 60 300 280 �g 260 240 J ' 220 '200 9 180 r z 16a r1950 1960 1970 19s0 1990 2000 2010 2020 j--rf 170 Bedrock Divide 4 160 t =1so L-J City Boundary A .140 M " Watercourse a 130 Major Road 120 �ts1� Monitoring Area Associated 110 ' Hydrograph(s) 100 C3 5an Luis Obispo Valley Basin 90 s0 1950 1960 1970 1990 1990 2000 2010 2020 1950 1960 1970 1990 1990 2000 2010 2020 ,�' � ' +� �< -jam \__ r -Q7 �1 390 370 350 330 5 310 290 270 250 �� 340 320 300 280 J' - 260 y � , 3 240 ;f 220 � 200 Jr rY J• 7 �.... tz; 1950 1960 1970 1980 1990 2000 7010 2020 r y� \ 1950 1960 1970 1980 1990 2000 2010 2020 " 1950 1960 1970 1980 19W 2000 2010 2020 -t rMr 3� - � � 320 300 280 260 din l�" yaa g 240 220 200 a� 180 Prepared tor: Author: AB Dat9: 1f16f2020 N A 0 -25 0.5 t ,,`yam\\1i Miles Reterences: C.NA� alConiatePlane California VLIPS 0405 Feet Pclotlon Lambert PrgeCtion'. Lambert C, 198 al Conic DIM S.b ,i.N.American y 2 5an Luis Obispo County Selected Hydrographs 0 0.425 0.65 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP �Kfl meters Figure 5-11 23 Page 199 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5.3 GROUNDWATER RECHARGE AND DISCHARGE AREAS Areas of significant areal recharge and discharge within the Basin are discussed below. Quantitative information about all natural and anthropogenic recharge and discharge is provided in Chapter 6: Water Budgets. 5.3.1 Groundwater Recharge Areas In general, natural areal recharge occurs via the following processes: 1. Distributed areal infiltration of precipitation, 2. Subsurface inflow from adjacent "non -water bearing bedrock", and 3. Infiltration of surface water from streams and creeks. 4. Anthropogenic recharge The following sections discuss each of these components. 5.3.1.1 Infiltration of Precipitation Areal infiltration of precipitation is a significant component of recharge in the Basin. Water that does not run off to stream or get taken up via evapotranspiration migrates vertically downward through the unsaturated zone until it reaches the water table. By leveraging available GIS data that defines key factors such as topography and soil type, locations with higher likelihood of recharge from precipitation have been identified. These examinations are desktop studies and therefore are conceptual in nature, and any recharge project would need a site -specific field characterization and feasibility study before implementation. Still, although they differ in scope and approach, the results of these studies provide an initial effort at identifying areas that may have the intrinsic physical characteristics to allow greater amounts of precipitation -based recharge in the Basin. Stillwater Sciences (Stillwater), in cooperation with the Upper Salinas -Las Tablas Resource Conservation District (USLTRCD), published a grant funded study (Stillwater 2015) designed to improve data gaps in the County's Integrated Regional Water Management (IRWM) plan. The Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California identified areas with relatively high natural percolation potential that, through management actions, could enhance local groundwater supplies for human and ecological benefits to the aquatic environment for steelhead habitat. The study used existing data in a GIS analysis to identify potentially favorable areas for enhanced recharge projects in the combined San Luis Creek and Pismo Creek Watershed. The results of the Stillwater-USLTRCD study are presented in Figure 5-12. The analysis indicates that approximately 2,220 acres in the Basin are categorized with high potential for intrinsic percolation, and 6,583 acres have medium potential. Conceptually, areas with higher potential for intrinsic percolation would transmit a higher percentage of rainfall to aquifer recharge. The largest area in the Basin that is classified with high recharge potential is the alluvium along East and West Corral de Piedras Creeks in the Edna Valley. The University of California (UC) at Davis and the UC Cooperative Extension published a study in 2015 that also uses existing GIS data to identify areas potentially favorable for enhanced groundwater recharge projects (UC Davis Cooperative Extension, 2015). While the Stillwater study focused on local San Luis 24 Page 200 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO Obispo stream corridors and emphasized fish habitat conditions, the UC study is statewide in scope includes more than 17.5 million acres, is scientifically peer reviewed, and focuses on the possibilities of using fallow agricultural land as temporary percolation basins during periods when excess surface water is available. The UC study developed a methodology to determine a Soil Agricultural Groundwater Banking Index (SAGBI) to assign an index value to agricultural lands through the state. The SAGBI analysis incorporates deep percolation, root zone residence time, topography, chemical limitations (salinity), and soil surface conditions into its analysis. The results of the SAGBI analysis in the Basin are presented in Figure 5-13. Areas with excellent recharge properties are shown in green. Areas with poor recharge properties are shown in red. Not all land is classified, but similar to the Stillwater map in Figure 5-12, this map provides guidance on where natural recharge likely occurs. The two studies discussed herein yield similar results in the Basin, particularly in Edna Valley. The Stillwater study identifies much of the drainage area of East and West Corral de Piedras Creeks, as well as area of alluvium of smaller streams t the southeast, as having high recharge potential. The SAGBI study identifies very similar areas in Edna Valley as having a moderately to good index value. These two studies, with differing methodologies, study areas, and objectives, converge on the characterization of the same portions of Edna Valley as having high natural recharge potential. By extension, areas with high natural recharge potential would be favorable locations to investigate the feasibility of enhanced recharge projects. If source water is available, water in these areas would have a higher likelihood of percolating to the underlying aquifers. 25 Page 201 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 1 A I Explanation Q San Luis Obispo Valley Basin Watershed Boundary Recharge Potential High * Low Medium All Other Features .�� -~„ C_J City Boundary Major Road •j �i ,« t ' �, Watercourse 1 Waterbody TANK FARM RE) 0 s PISMO B E A C H ,,\ Prepared for: (\' References: 1 V 1. Coordinate System: NAD al C SLatePlane California V FIPS 0405 Feet Author: AB 0 0.25 0.5 1 Projection: Lambert Conformal Conic Date: 1/20/2020 Miles Datum: North American 1983 2.San Luis Obispo County 0 0,425 0,85 1.7 3. The Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, SAN LUIS OBISPO VALLEY BASIN GSP Kilometers California (Stillwater, 2015) 10 A , �0 :y►r R �y yam' �3 r ' '�- ,�'� fix• 8� 111Y , 46 Stillwater Percolation Zone Study Results Figure 5-12 26 Page 202 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Explanation San Luis Obispo Valley Basin .} N- Road Watercourse Soil Agricultural Groundwater � �_ k'y�_ » � -'• • f / h �� Banking Index (SAGBI) Excellent Good vdd;" Moderately Good Siren Luis 0hisqm r Moderately Poor Poor Very Poor Ohl �• e i J� 4- e.Nt - 7 �+.�� 1 vj Prepared for: ^ References: 10Author: NP Dale t/142020 - V A p 0-25 t13 1 Oil- 1. Coordinate System: NA]] 1983 StatePla ne CaLfomla V FIPS 0405 Feet ProjectionLambert Conformal Conic : . 2 mS Nnh American enti Z Soil SuahiIndex 11983 es PotentialAreas for GroundwaterEar king on Agricultural Lands, Nay 0 0.425 0.85 1.7 11C Davis and JC Cooperative Extension. SAN LUIS OBISPO VALLEY BASIN [i5P �Kilamatera Soil Agricultural Groundwater Banking Index Study Results Figure 5-13 27 Page 203 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5.3.1.2 Subsurface Inflow Groundwater Conditions (§ 354.16) Subsurface inflow is the flow of groundwater from the surrounding bedrock into the basin sediments. This process is sometimes referred to as mountain front recharge. Groundwater flows from areas of high head to areas of lower head, and water levels in the mountains are at a higher elevation than the Basin. Flow across the basin boundary is predominantly via highly conductive, but random and discontinuous fracture systems. The rate of subsurface inflow to the Basin from the surrounding hill and mountain area varies considerably from year to year depending upon precipitation (intensity, frequency and duration, seasonal totals, etc.) and groundwater level gradients. There are no available published or unpublished inflow data for the hill and mountain areas surrounding the Basin. An estimate of this component of recharge is presented in Chapter 6 (Water Budget). 5.3.1.3 Percolation of Streamflow Percolation of streamflow is a locally significant source of recharge in areas where the local creeks enter the Basin. Water levels in wells monitored by the County in the area where Corral de Piedras Creeks enter the Basin reflect this phenomenon, as discussed in the previous discussion of water level elevations in the Basin. Groundwater recharge from percolation of streamflow is thought to occur in the area along Davenport Creek, near Buckley Road as well. Most wells in this vicinity are on the order of 100 feet deep, which is too deep to be screened only in the local alluvium; these wells are assumed to screen the Paso Robles Formation Aquifer. During the seasonal winter rains when the creeks are flowing, groundwater levels are at approximately the same level as the water in the creek. During the dry season, water levels decrease to about 15 to 20 feet below land surface. Therefore, the alluvium appears to recharge the underlying Paso Robles Formation in this area. It is likely that similar processes contribute to recharge via percolation of streamflow along the San Luis Creek corridor, as well. Specific isolated monitoring of alluvial wells compared to the underlying aquifers' water levels could clarify this recharge component. 5.3.1.4 Anthropogenic Recharge Significant anthropogenic recharge occurs via the three processes discussed below: Percolation of treated wastewater treatment plant (WWTP) effluent, Percolation of return flow from agricultural irrigation, and Percolation of return flow from domestic septic fields. A wastewater treatment plant serving the City of San Luis Obispo operates within the Basin on Prado Road along San Luis Creek. Treated wastewater effluent from this plant is discharged to San Luis Creek and used in the City's recycled water system for irrigation and construction -related uses. The County operates a small WWTP near the golf course in the service area of Golden State Water Company, and uses the effluent largely to irrigate the golf course. Residences in Edna Valley beyond the city or county WWTP service area dispose of wastewater via septic tanks. Water from septic fields can percolate into the underlying aquifers. Irrigated agriculture is prevalent in the Basin, especially along Los Osos Valley Road and in Edna Valley. Return flows from irrigated agriculture occur when water is supplied to the irrigated crops in excess of the crop's water demand. This is done to avoid excess build-up of salts in the soil and overcome non -uniformity in the irrigation distribution system. These are all general standard practices. W Page 204 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.3.2 Groundwater Discharge Areas Natural groundwater discharge occurs as discharge to springs, seeps and wetlands, subsurface outflows, and evapotranspiration (ET) by phreatophytes. Figure 5-14 includes the locations of significant active springs, seeps, and wetlands within or adjacent to the Basin identified from previous studies or included on USGS topographic maps covering the watershed area. There are no mapped springs or seeps located within the Basin boundaries; most are located at higher elevations in the surrounding mountain areas. Natural groundwater discharge can also occur as discharge from the aquifer directly to streams. Groundwater discharge to streams and potential groundwater dependent ecosystems (GDEs) are discussed in Section 5.8. In contrast to mapped springs and seeps, whose source water generally comes from bedrock formations in the mountains, groundwater discharge to streams is derived from the alluvium. Discharge to springs or streams can vary seasonally as precipitation and stream conditions change throughout the year. Groundwater discharge to the Corral de Piedras Creeks occur seasonally at the location where the creeks leave the basin, where relatively impermeable bedrock rises to the surface along the Edna Fault, causing groundwater to daylight at this location, at least in the wet season. Subsurface outflow and ET by phreatophytes are discussed in Chapter 6 (Water Budget). 5.4 CHANGE IN GROUNDWATER STORAGE Changes in groundwater storage for the Alluvial Aquifer and Paso Robles Formation Aquifer are correlated with changes in groundwater elevation, previously discussed, and are addressed in Chapter 6 (Water Budget). 5.5 SEAWATER INTRUSION Seawater intrusion is not an applicable sustainability indicator for the Basin. The Basin is not adjacent to the Pacific Ocean, a bay, or inlet. 5.6 SUBSIDENCE Land subsidence is the lowering of the land surface. While several human -induced and natural causes of subsidence exist, the only process applicable to the GSP is subsidence due to lowered groundwater elevations caused by groundwater pumping. Historical incidence of subsidence within the Basin was discussed in Chapter 4 (Basin Setting). Direct measurements of subsidence have not been made in the Basin using extensometers or repeat benchmark calibration; however, interferometric synthetic aperture radar (InSAR) has been used in the County to remotely map subsidence and DWR is expected to continue to collect InSAR data. This technology uses radar images taken from satellites that are used to map changes in land surface elevation. One study done in the area, which evaluates the time period between spring 1997 and fall 1997 (Valentine, D. W. et al., 2001), did not report any measurable subsidence within the Basin. Subsidence as a sustainability indicator will be addressed further in Chapter 8. 29 Page 205 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO 5.7 INTERCONNECTED SURFACE WATER Surface water/groundwater interactions may represent a significant, portion of the water budget of an aquifer system. Where the water table is above the streambed and slopes toward the stream, the stream receives groundwater from the aquifer; that is called a gaining reach (i.e., it gains flow as it moves through the reach). Where the water table is beneath the streambed and slopes away from the stream, the stream loses water to the aquifer; that is called a losing reach. In addition, a stream may be disconnected from the regional aquifer system if the elevation of streamflow and alluvium is significantly higher than the elevation of the water table in the underlying aquifer. The spatial extent of interconnected surface water in the Basin was evaluated using water level data from Alluvial Aquifer and Paso Robles Formation Aquifer wells adjacent to the Basin creeks and streams. In accordance with the SGMA Emergency Regulations §351 (o), "Interconnected surface water refers to surface water that is hydraulically connected at any point by a continuous saturated zone to the underlying aquifer and the overlying surface water is not completely depleted". The interconnected surface water analysis for the Basin consisted of comparing average springtime water level elevations in wells adjacent to the San Luis Creek with the elevation of the adjacent San Luis Creek channel. In cases where average springtime water levels were greater than the elevation of the adjacent San Luis Creek channel, the stream reach was considered as potentially 'gaining'. In cases where average springtime water levels were below the adjacent channel elevation, the stream reach was considered 'losing' and potentially 'disconnected'. It is important to recognize that the results of these analyses may reflect conditions that occur occasionally, in response to precipitation events. They may not be representative of long-term average conditions. The analysis outlined above resulted in identification of two areas of San Luis Creek that occasionally 'gain' water from the Alluvial Aquifer; the confluence of Stenner Creek and San Luis Creek, and the reach of San Luis Creek downstream from the Wastewater Treatment Plant to the confluence with Prefumo Creek. These are displayed in Figure 5-14. Several reaches of San Luis Creek are identified that occasionally 'lose' water to the Alluvial Aquifer. Groundwater levels in the San Luis Valley part of the Basin are generally high enough that the creek is connected to the underlying aquifer. Along most of Corral de Piedras Creeks, by contrast, surface water levels are generally greater than 30 feet above the groundwater level, and the streams are considered disconnected from the underlying Alluvial Aquifer in this area. 5.7.1 Depletion of Interconnected Surface Water Groundwater withdrawals are balanced by a combination of reductions in groundwater storage and changes in the rate of exchange across hydrologic boundaries. In the case of surface water depletion, this rate change could be due to reductions in rates of groundwater discharge to surface water, and increased rates of surface water percolation to groundwater. Seasonal variation in rates of groundwater discharge to surface water or surface water percolation to groundwater occur naturally throughout any given year, as driven by the natural hydrologic cycle. However, they can also be affected by anthropogenic actions. Since, as presented in the discussion of hydrographs in the San Luis Valley in Section 5.2, there has been no long- term water level declines in this area, there is no evidence of long-term depletion of interconnected surface water in this area. 5.8 POTENTIAL GROUNDWATER DEPENDENT ECOSYSTEMS The SGMA Emergency Regulations §351.16 require identification of groundwater dependent ecosystems within the Basin. Several datasets were utilized to identify the spatial extent of potential groundwater 30 Page 206 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO dependent ecosystems (GDEs) in the Basin, as discussed in the following sections. In accordance with the SGMA Emergency Regulations §351 (o), "groundwater dependent ecosystems refers to ecological communities or species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface". In areas where the water table is sufficiently high, groundwater discharge may occur as evapotranspiration (ET) from phreatophyte vegetation within these GDEs. The overall distribution of potential GDEs within the Basin has been initially estimated in the Natural Communities Commonly Associated with Groundwater (NCCAG) dataset (DWR, 2018). This dataset was reviewed by Stillwater Sciences, and the resulting distribution of potential GDEs is shown in Figure 5-15. There has been no verification that the locations shown on this map constitute GDEs. Additional field reconnaissance is necessary to verify the existence and extent of these potential GDEs, and may be considered as part of the monitoring network for future planning efforts. 5.8.1 Hydrology 5.8.1.1 Overview of GDE Relevant Surface and Groundwater Hydrology Instream flows in San Luis and Pismo Creeks can be divided into wet season flows, typically occurring from January to April, and dry season flows, typically from June to October. Short transitional periods occur between the wet and dry seasons. Wet season instream flows originate from a range of sources including precipitation -driven surface runoff events, water draining from surface depressions or wetlands, shallow subsurface flows (e.g., soil), and groundwater discharge. Dry season instream flows, however, are likely fed primarily by groundwater discharge. As groundwater levels fall over the dry season, so do the corresponding instream flows. If groundwater elevations remain above instream water elevations, groundwater discharges into the stream and surface flows continue through the dry season (creating perennial streams). If groundwater elevations fall below the streambed elevation, the stream can go dry. Streams that typically flow in the wet season and dry up in the dry season are termed intermittent. Over time, streams can transition from historically perennial to intermittent conditions due to climactic changes or groundwater pumping (Barlow and Leake 2012). Dry season flows supported by groundwater are critical for the survival of various special status species, including the federally threatened California red -legged frog (Rana draytonii) and Steelhead (Oncorhynchus mykiss). San Luis Creek and Pismo Creek are underlain by the Alluvial Aquifer, the Paso Robles Formation Aquifer, and the Pismo Formation Aquifer, as previously discussed. These aquifers have hydraulic connection to one another, and to surface waters, but the degree of connection varies spatially. Aquifers can include confined aquifers, unconfined aquifers, and perched aquifers (Chapter 4). Aquifers can discharge into ponds, lakes or creeks or vice versa. In the San Luis Obispo Valley Groundwater Basin, little data exists to characterize the connection between surface water and groundwater. While the groundwater in the San Luis Valley and Edna Valley is hydraulically connected, a shallow subsurface bedrock divide between the two sub -areas partially isolates the deeper portions of the two aquifers (Figure 5-10 and Figure 5-11). Groundwater in the Edna Valley flows both towards the San Luis Valley in the northwest portion of the basin and towards Price Canyon in the southwest portion of the basin. Groundwater flowing towards Price Canyon rises to the surface as it approaches the bedrock constriction of Price Canyon and the Edna fault system. The 1954 DWR groundwater elevation map (Figure 5-1) best illustrates the pre -development groundwater flow from the Edna Valley both towards San Luis Obispo and into Price Canyon. Observations of stream conditions indicate a perennial reach of Pismo Creek that flows through Price Canyon and supports year-round critical habitat for threatened steelhead just south of the Basin Boundary. A conceptual explanation for this is that groundwater from the Edna sub -area flows towards the discharge area at Price Canyon, and rises to the surface (daylights) as the groundwater 31 Page 207 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) flow encounters the impermeable zone of the Edna Fault and the bedrock outside of the Basin. Piezometers in this area could confirm this interpretation of observed stream conditions. 5.8.1.2 Losing and Gaining Reaches Streams are often subdivided into losing and gaining reaches to describe their interaction of surface water in the stream with groundwater in the underlying aquifer. In a losing reach water flows from the stream to the groundwater, while in a gaining reach water flows from the groundwater into the stream. The connection between losing reaches to the regional aquifer may be unclear as water can be trapped in perched aquifers above the regional water table. Figure 5-14 shows the likely extent of known gaining and losing reaches in San Luis and Pismo Creeks during typical dry season conditions. This map is compiled from various data sources, including: • A field survey of wet and dry reaches of San Luis Creek (Bennett 2015), • Field surveys and flow measurements of Pismo Creek (Balance Hydrologics 2008), • An instream flow study of Pismo Creek (Stillwater Sciences 2012), • A regional instream flow assessment that included San Luis and Pismo Creeks (Stillwater Sciences 2014), • Spring and summer low flow measurements in San Luis and Pismo Creeks (2015-2018) (Creek Lands Conservation 2019), and • Consideration of the effects of local geologic features such as bedrock outcrops and faults, both of which can force deeper groundwater to the surface. The effect of faults and bedrock outcrops can be localized or extend for some distance downstream. Portions of the San Luis and Pismo Creeks and their tributaries for which no data exist are left unhighlighted in Figure 5-14. In general, the extent of losing or gaining reaches can vary by water year type or pumping conditions. East and West Corral de Piedras Creeks on the north-east side of the basin can be dry in the spring and summer during drier years but be flowing, losing reaches in wetter years (Creek Lands Conservation 2019). (To be clear, a stream segment can be a losing reach even if it is not hydraulically connected to the aquifer, since the stream will be losing surface flow to the subsurface via percolation.) In contrast, gaining reaches shown on San Luis Obispo Creek are fairly consistent across water year types (Bennett 2015, Creek Lands Conservation 2019). Figure 5-14 is based on limited data sources. Improved surface flow monitoring is recommended to refine and update the extent of losing and gaining reaches, as well as to provide data for unhighlighted reaches. 32 Page 208 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO u Groundwater Conditions (§ 354.16) S AN Fion„..ie k • •� „� Explanation • • �- = `�fJ i'' • Spring Gaining Reach O _ O 00 a_ Dnve,iP0 C - WF 4�4 40 At PIS.. /4i ti - Losing Reach Aw �` �+ �► Watershed Boundary • -x �+�� Q San Luis Obispo Valley Basin All Other Features �,fi � r, - _ L_J City Boundary Major Road Watercourse Waterbody 46 •//,'� = Alf TANK FARM • :fir 1 - �� , , - , � �, ireek r Y o C+.00 tE�NGoIb Creek cep �-.� - IF'a/�: err— �i �✓ �e�oo ce'` e4 ea,a , 110`� �eaeP ^,.• .... � y ! s �l ,�„ r �� P;ISMO CREEK w v� i O �. n9 C,it �p q v II Prepared for: Author- AB Date: 1/16/2020 0 N1. A 0 0.25 0.5 t Miles References: Coordinate System: NAD 1983 StatePlane California V RIPS 0405 Feet Projection: Lambert Conformal Conic Datum: North American 1983 2. San Luis Obispo County N{ 0 0.425 0.85 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP Kilometers 4. ESRI 5. Stillwater Sciences W Losing and Gaining Reaches Within the Basin Figure 5-14 33 Page 209 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5.8.2 Vegetation and Wetland Groundwater Dependent Ecosystem Identification DWR has compiled a statewide Natural Communities Commonly Associated with Groundwater (NCCAG) database (DWR 2019). This database identifies potentially groundwater dependent ecosystems based on the best available vegetation and wetland data (Klausmeyer et al. 2018). DWR identifies potentially groundwater dependent wetland areas using National Wetland Inventory (NWI) wetland data (USFWS 2018). These data were evaluated and assessed to accurately capture wetland and riverine features. In the Basin, the best available vegetation mapping data set was from the California Fire and Resource Assessment Program Vegetation (FVEG, California Department of Forestry and Fire Protection 2015). FVEG is a remotely sensed dataset that classifies vegetation to coarse types (i.e., the California Wildlife Habitat Relationship System). Given the limitations of this dataset to accurately capture and identify vegetation using a precise classification system, it was deemed inappropriate for use in determining potential GDEs. Instead, a manual assessment of vegetation with potential groundwater dependence was conducted using National Agricultural Imagery Program 2018 color aerial imagery (NAIP 2018). Vegetation communities identified as potentially groundwater dependent included riparian trees and shrubs, and oak woodlands. Oak woodlands were considered potentially groundwater dependent due to their deep rooting depths (up to 70 feet [Lewis and Burgy 19641). Potential vegetation and wetland GDEs were retained if the underlying depth to water in 2019 was inferred to be 30 feet or shallower based on the existing well network (Figure 5-15). Depth to groundwater was interpolated from seventeen wells for which groundwater level data was available in the spring of 2019 (Figure 5-6). The depth to groundwater estimated in Figure 5-15 is assumed to represent regional groundwater levels; however, the screening depth is known for only 6 of the 17 of the wells. Wells where the screened depth is unknown may be measuring groundwater levels for deeper aquifers that are unconnected to the shallow groundwater system, and thus groundwater deeper than 30 ft for a given well may not reflect the absence of shallow groundwater, but instead reflects the absence of data. To determine the hydraulic connectivity between potential perched aquifers to the regional aquifer, additional monitoring with nested piezometers could be utilized. For the purposes of differentiating between potential and unlikely GDE's, different assumptions were made for the San Luis Valley versus Edna Valley in areas of no groundwater data. In the San Luis Valley, underlying San Luis Creek, it was assumed that the depth to regional groundwater was less than 30 feet because the limited available data indicate that groundwater in this sub -area is generally relatively shallow. In the Edna Valley (underlying Pismo Creek), it was assumed that the depth to regional groundwater was more than 30 feet because the limited available data indicate that the groundwater in this sub -area is generally deeper; therefore, much of the area of the lower reaches of East and West Corral de Piedras Creeks is unlikely to have GDEs. One exception to this assumption was made on upper East Corral de Piedra where the conditions were assumed to be similar to those on upper West Corral de Piedra where early dry season wet conditions have been observed by Stillwater Sciences and Balance Hydrologics (2008). The 30-foot depth criterion is consistent with guidance provided by The Nature Conservancy (Rohde et al. 2019) for identifying GDEs. Additionally, the area where East and West Corral de Piedras Creeks leave the Basin near Price Canyon has groundwater elevation data within 30 feet of the streams, and so are presented as having potential GDEs. 34 Page 210 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO LUI'S OBISPD rrrCRE=EK A .01 00 .�. y •_. Groundwater Conditions (§ 354.16) I r4 rIFrr+y- aEkCH t s 06 die- + rfv biu+u .+s Prepared for I%k 0 A� 1 *1 o oss 05 1 References: 1 CoortlneL Sryvam. HAD 1903 �akePla ie Callorrm V FlP3 BIOS Feat FnNa-bLrlCuivmaiCles'orthAenancan 1963Lua Otws C—rrly SANLUISOBFSPQ VALLEY BASIN GSP 0 0425 Day 1C'S abmcse: ,.ESR� 5. 5[lrwmer Sclenoes Expfanation Potential GDE Un likely G D E (groundwater likely > 36 ft) Estimated Groundwater Depth C3 Depth to Water 5 30 feet C:j Depth to Water ? 39 feet (� Watershed Boundary 0 San Luis Obispo Valley Basin All Other Features [ J City Boundary N Major Road Watercourse Waterbody _900 . Ylr} tiaA{ f Fi P I S M 0 C R E F K r � Potential Groundwater -Dependent Ecosystems (GDEs) Ftguro 5-15 35 Page 211 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5.8.3 Identification of Special -Status Species and Sensitive Natural Communities Associates with GDE's For the purposes of this GSP, special -status species are defined as those: • Listed, proposed, or under review as endangered or threatened under the federal Endangered Species Act (ESA) or the California Endangered Species Act (CESA); • Designated by California Department of Fish and Wildlife (CDFW) as a Species of Special Concern; • Designated by CDFW as Fully Protected under the California Fish and Game Code (Sections 3511, 4700, 5050, and 5515); • Protected under the federal Bald and Golden Eagle Protection Act; • Designated as rare under the California Native Plant Protection Act (CNPPA); and/or • Included on CDFW's most recent Special Vascular Plants, Bryophytes, and Lichens List (CDFW 2019a) with a California Rare Plant Rank (CRPR) of 1, 2, 3, or 4. In addition, sensitive natural communities are defined as: Vegetation communities identified as critically imperiled (S1), imperiled (S2), or vulnerable (S3) on the most recent California Sensitive Natural Communities List (CDFW 2019b). To determine the terrestrial and aquatic special -status species that may utilize potential GDE units overlying the Basin, Stillwater ecologists queried existing databases on regional and local occurrences and distributions of special -status species. Databases accessed include the California Natural Diversity Database (CNDDB) (CDFW 2019c), eBird (2019), and TNC freshwater species list (TNC 2019). Spatial database queries were centered on the potential GDEs plus a 1-mile buffer. Stillwater's ecologists reviewed the database query results and identified special -status species and sensitive natural communities with the potential to occur within or to be associated with the vegetation and aquatic communities in or immediately adjacent to the potential GDEs. The table in Appendix 513 lists these special -status species and sensitive natural communities, describes their habitat preferences and potential dependence on GDEs, and identifies known nearby occurrences (Appendix B - Table 1). Wildlife species were evaluated for potential groundwater dependence using the Critical Species Lookbook (Rohde et al. 2019). The San Luis Obispo Valley Groundwater Basin supports steelhead belonging to the South -Central California Coast Distinct Population Segment (DPS) which is federally listed as "threatened." Within this DPS, the population of steelhead within the San Luis Creek, and Pismo Creek portions of the groundwater basin have both been identified as Core 1 populations which means they have the highest priority for recovery actions, have a known ability or potential to support viable populations, and have the capacity to respond to recovery actions (NMFS 2013). One critical recovery action listed by the National Marine Fisheries Service (NMFS) includes the management of groundwater extractions for protection and restoration of natural surface flow patterns to ensure surface flows allow for essential steelhead habitat functions (NMFS 2013). Based on criteria promulgated by The Nature Conservancy (TNC), the San Luis Obispo Valley Groundwater Basin was determined to have high ecological value because: (1) the known occurrence and presence of suitable habitat for several special -status species including the Core 1 population status of South -Central California Coast Steelhead DPS and several special -status plants and animals that are directly or indirectly dependent on groundwater (Appendix B - Table 1); and (2) the vulnerability of these species and their habitat to changes in groundwater levels (Rohde et al. 2018). 36 Page 212 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5.9 GROUNDWATER QUALITY DISTRIBUTION AND TRENDS Groundwater quality samples have been collected and analyzed throughout the Basin for various studies and programs and are collected on a regular basis for compliance with regulatory programs. Water quality data surveyed for this GSP were collected from: The California Safe Drinking Water Information System (SDWIS), a repository for public water system water quality data, The National Water Quality Monitoring Council water quality portal (this includes data from the recently decommissioned EPA STORET database, the USGS, and other federal and state entities [Note: in the Basin the agencies include USGS, California Environmental Data Exchange Network (CEDEN), and Central Coast Ambient Monitoring Program (CCAMP}]), and The California State Water Resources Control Board (SWRCB) GeoTracker GAMA database. In general, the quality of groundwater in the Basin is good. Water quality trends in the Basin are stable, with no significant trends of ongoing deterioration of water quality based on the Regional Water Quality Control Board's Basin Objectives, outlined in the Water Quality Control Plan for the Central Coast Basin (Basin Plan, June 2019). The Basin Plan takes all beneficial uses into account and establishes measurable goals to ensure healthy aquatic habitat, sustainable land management, and clean groundwater. The distribution, concentrations, and trends of some of the most commonly cited major water quality constituents are presented in the following sections. 5.9.1 Groundwater Quality Suitability for Drinking Water Groundwater in the Basin is generally suitable for drinking water purposes. Groundwater quality data was evaluated from the SDWIS and GeoTracker GAMA datasets. The data reviewed includes 2,885 sampling events from 403 supply wells and monitoring wells in the Basin, collected between June 1953 and September 2019. Primary drinking water standards Maximum Contaminant Levels (MCLs) and Secondary MCLs (SMCLs) are established by Federal and State agencies. MCLs are legally enforceable standards, while SMCLs are guidelines established for nonhazardous aesthetic considerations such as taste, odor, and color. Primary water quality standard exceedances in the Basin include exceedance of the MCL for nitrate, which equaled or exceeded the standard in 269 samples out of 2,605 samples (or 10% of samples, with 190 of the exceedances occurring in four wells), and exceedance of the MCL for arsenic, which exceeded the MCL in 30 out of 771 samples (or 4% of samples collected). The SMCL for total dissolved solids (TDS) was equaled or exceeded in 126 out of 843 samples (or 15% of total samples). In the case of public water supply systems, these water quality exceedances are effectively mitigated with seasonal well use, treatment, or water blending practices to reduce the constituent concentrations to below their respective water quality standard. In general, these statistics meet the Central Coast Water Board Basin Plan measurable goals that by 2025, 80% of groundwater will be clean, and the remaining 20% will exhibit positive trends in key parameters. 5.9.2 Distribution and Concentrations of Point Sources of Groundwater Constituents Potential point sources of groundwater quality degradation due to release of anthropogenic contaminants were identified using the State Water Resources Control Board (SWRCB) Geotracker website. Waste Discharge permits were also reviewed from on-line regional SWRCB websites. Table 5-1 summarizes information from these websites for open/active sites. Figure 5-16 shows the locations of these open 37 Page 213 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) groundwater contaminant point source cases, and the locations of completed/case closed sites. Based on available information there are no mapped ground -water contamination plumes at these sites. MI Page 214 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Fionni C:r�rk .,t Orr��� _ • » N • v"° Explanation • Open/Active/Pending Site 1 ..+% • Completed - Case Closed Site t - . ,T " «i �ti A>• r- t � Q San Luis Obispo Valley Basin 00 d i076659e5 ♦ �' All Other Features t-J City Boundary 3 �/ , �r�� I� / /N/ Major Road mf Watercourse ; j low" Allo� Waterbody T10000000060 , `�j.� �y _ - '��- �� • T10000012125._-_1 ✓ �t '� - f •�`� r ! a'�`y' • S A N L U I S •• •• OBISPO • jjSL203011375 0000002287 % f/ ti 3 • T10000010082 r( v f— J , — / ' ♦ B A C •. 7" P, I C I I' I C U C IC .1 \' Prepared for: Author: AB Date: 11/27l2019 SAN LUIS OBISPO VALLEY BASIN GSP P I S M O B E A C H TANK FARM RD T1 N References: 1, Coordinate System: NAD 19113 S1a1ePlane California V RIPS O405 Feet 0 0.25 0.5 1 Miles Projection: Lambert Conformal Conic Datum: North American 983 A 2.San Luis Obispo County 0 0.425 0.85 1.7 3. Di,i,lobe 20111 Kilometers Location of Potential Point Sources of Groundwater Contaminants Figure 5-19 39 Page 215 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) Table 5-1: Potential Point Sources of Givuiit- Site ID Site Name Case Type Status Constituent(s) of Concern (COCs) Potentially Affected Media T0607900100 American Gas and Tire LUST Cleanup Site Open - Verification Monitoring Benzene, Gasoline, MTBE / TBA / Other Fuel Oxygenates Aquifer used for drinking water supply SL203011375 Chevron (Former UNOCAL) -Tank Farm Road Bulk Storage Cleanup Program Site Open - Remediation Arsenic, Lead, Asphalt, Crude Oil, Other Petroleum Contaminated Surface / Structure, Other Groundwater (uses other than drinking water), Soil, Surface water T10000002287 Conoco Phillips site # 5143 Cleanup Program Site Open - Site Assessment Crude Oil, Diesel, Gasoline Soil SL0607944973 COP Pipeline at San Luis Drive Cleanup Program Site Open - Assessment & Interim Remedial Action Crude Oil Other Groundwater (uses other than drinking water), Well used for drinking water supply T10000001025 KIMBALL MOTORS Cleanup Program Site Open -Verification Monitoring Other Chlorinated Hydrocarbons, Tetra chIoroethylene (PCE), Trichloroethylene (TCE), Vinyl chloride Aquifer used for drinking water supply, Soil SLT3S0851312 MODEL INDUSTRIAL SUPPLY Cleanup Program Site Open - Site Assessment Aquifer used for drinking water supply SLT3S0161285 PG&E -FORMER MANUFACTURED GAS PLANT-SAN LUIS OBISPO Cleanup Program Site Open - Remediation Aquifer used for drinking water supply SL0607937854 PISMO ST. AND MORRO ST. PIPELINE RELEASE Cleanup Program Site Open - Site Assessment Crude Oil Aquifer used for drinking water supply T10000012768 SAN LUIS COUNTY RGNL Non -Case Information Pending Review Per- and Polyfluoroalkyl Substances (PFAS) T10000002286 South Higuera St & Pismo St Pipeline (Chevron Site 351317) Cleanup Program Site Open - Site Assessment Crude Oil, Diesel, Gasoline Aquifer used for drinking water supply, Soil T10000010079 Thread Lane Properties, LLC Cleanup Program Site Open - Site Assessment SL0607965995 TRACT 1259 Cleanup Program Site Open - Assessment & Interim Remedial Action Crude Oil Aquifer used for drinking water supply T10000000060 Union Pacific Railroad - Round House/Pond Site Cleanup Program Site Open - Inactive Waste Oil / Motor / Hydraulic / Lubricating Other Groundwater (uses other than drinking water), Soil T10000012125 UPRR Tie Fire Non -Case Information Pending Review T10000010082 Volny Investment Company Cleanup Program Site Open - Site Assessment Page 216 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) 5.9.3 Distribution and Concentrations of Diffuse or Natural Groundwater Constituents The distribution and concentration of several constituents of concern are discussed in the following subsections. Groundwater quality data was evaluated from the SDWIS and GeoTracker GAMA datasets. The data reviewed includes 2,884 sampling events from 403 wells in the Basin, collected between June 1953 and June 2019. Each of the constituents are compared to their drinking water standard, if applicable, or their Basin Plan Median Groundwater Quality Objective (RWQCB Objective) (CCRWQCB, 2017). This GSP focuses only on constituents that might be impacted by groundwater management activities. The constituents discussed below are chosen because they have either a drinking water standard, a known effect on crops, or concentrations have been observed above either the drinking water standard or the level that affects crops. 5.9.3.1 Total Dissolved Solids TDS is defined as the total amount of mobile charged ions, including minerals, salts or metals, dissolved in a given volume of water and is commonly expressed in terms of milligrams per liter (mg/L). Specific ions of salts such as chloride, sulfate, and sodium may be evaluated independently, but all are included in the TDS analysis, so TDS concentrations are correlated to concentrations of these specific ions. Therefore, TDS is selected as a general indicator of groundwater quality in the Basin. TDS is a constituent of concern in groundwater because it has been detected at concentrations greater than its RWQCB Basin Objective of 900 mg/I in the Basin. The TDS Secondary MCL has been established for color, odor and taste, rather than human health effects. This Secondary MCL includes a recommended standard of 500 mg/L, an upper limit of 1,000 mg/L and a short-term limit of 1,500 mg/I. TDS water quality results ranged from 180 to 3,100 mg/I with an average of 727 mg/I and a median of 613 mg/l. The distribution and trends of TDS concentrations in the Basin groundwater are presented on Figure 5-16. TDS concentrations are color coded and represent the average result if multiple samples are documented. Most of the samples with the highest values (dark red in the figure) are outside or on the edge of the Basin. This is consistent with observations that groundwater from the Basin sediments generally has better water quality than groundwater from bedrock wells. Eleven wells with the greatest amount of data over time were selected. Graphs displaying TDS concentration with time are included on Figure 5-17. Most of these graphs do not display any upward trends in TDS concentrations with time. The sustainability projects and management actions implemented as part of this GSP are not anticipated to increase groundwater TDS concentrations in wells that are currently below the SMCL. 41 Page 217 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Groundwater Conditions (§ 354.16) O • O Gs • OSOS L. O M0 - , 3,500 G 3,000 2 E 2,5ao S 2,000 c 1,500 My I.0 SMCL 1 m 1 ° 1990 Ms 2. Ms 2010 2.5 202° ram, �r � 3,500 . i ,i jr c z,sao ,. � J .2 2,a90 �• ati - 1,sao �f ii 1,000 SMCL 10 m �{ 1990 1995 2000 2005 2020 2015 2020 If rJ� P I S M O B E A C H 05. AN 'hill 00 s,000 6 ,ems E2,s0o 1W .2 2A00 • V 1,sao u 109° '.SMCL 1,0 mg/I o sao 0 1990 1995 2000 2005 2010 2015 2020 CO r--------- TANK FA O m • •\ �_,----•moo b o O 3,50° 4 E z,soo 2,000 e & 1,soo `o i,o00 SMCL 1 m I � s00 a 19W 1995 20M zoos 2010 2015 2020 _.1, _ iy ` tar v - ,ii 0 1990 5 20M 2W5 2010 2015 2020 ....._. • 47%Explanation Yj`' TDS Concentration (mg/1) • 0 - 500 1 O 500 - 750 Of O 750 - 1000 1'S00 7 O 1000 - 1500 9,00a E 2,500 WOW 2,a0a • > 1500 1,500 3100o sMa l,o0 1 �, - All Other Features San Luis Obispo Valley Basin 0 19N 1995 21M zoos 2010 20U W20 9,seo `3,000 8 E z,soo z,o00 1,s0a 0 1,009 SMCL=1 F 500 0 19N 1995 2000 20os 20M 2035 W20 © O Ao� 1 Greolc G O a Ro O O ERPNOH C O G+°`M og�oo r'td`�11a0 `Ayc`°o1 O � �8,r�+r La+ra o ° o 0 0 O }� O' O O O Prepared for: N References: 0 1. Coordinate System: NAD SLatePlane Calrfornia V FIPS O405 Feet Author: A8 A 0 0.25 0.5 1 Projection: Lambert Conformalal Conic Date: 1/16/2020 ,.•�\\V{` Miles Datum: North American 1983 2.San Luis Obispo County 0 0,425 0,85 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP Kilometers 01"-.- ..--M .ed [ -J I y oun ary +p r Major Road Watercourse Waterbody fir- 9,ee0 9 2,000 �- d 1,500 - J' - j rY ..�►- u 1,000 SMCL Soo�� 01990 Ms 2000 2005 2010 2015 2020AW ice/ I1 / `•��.r+ ti ftw �a aa 9,seo 9 =''.0 11 E z,soo f' = 2,000 � 1,500 s1Mo SMCL 10 m O .0 0 19% MS 20W 2005 2010 2015 2020 Distribution of TDS in Basin Figure 5-16 42 Page 218 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5.9.3.2 Nitrate Groundwater Conditions (§ 354.16) Nitrate (as Nitrogen) is a widespread contaminant in California groundwater. Although it does occur naturally at low concentrations, high levels of nitrate in groundwater are associated with agricultural activities, septic systems, confined animal facilities, landscape fertilizers and wastewater treatment facilities. Nitrate is the primary form of nitrogen detected in groundwater. It is soluble in water and can easily pass through soil to the groundwater table. Nitrate can persist in groundwater for decades and accumulate to high levels as more nitrogen is applied to the land surface each year. It is a Primary Drinking Water Standard constituent with an MCL of 10 mg/I. Nitrate is a constituent of concern in groundwater because it has been detected at concentrations greater than its RWQCB Basin Objectives of 5 mg/I (as N) in the Basin. The Nitrate MCL has been established at 10 mg/I (as N). Overall, nitrate water quality results ranged from below the detection limit to 80 mg/I (as N) with an average of 3.9 mg/I (as N) and a median value of 2.0 mg/I (as N). Figure 5-18 presents occurrences and trends for nitrate in the Basin groundwater. Wells with the most sampling data overtime were selected for presentation. The color -coded symbols represent the average result if multiple samples are documented. Most of the chemographs displayed on Figure 5-18 indicate concentrations of nitrate well below the MCL, and do not indicate trends of increasing concentrations with time. Chemographs labelled number 4 and 5 on Figure 5-18 do appear to indicate a slight upward trend in nitrate (as nitrogen) concentrations over the data period of record. Sustainability projects and management actions implemented as part of this GSP are not anticipated to increase nitrate concentrations in groundwater in a well that would otherwise remain below the MCL to increase above the MCL. 43 Page 219 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO ��s 1 16 e� E 13 1 16 MCL=10 I Q 8 g 6 4 £ 2 0 19W 1995 20W 2005 2010 2015 W20 Groundwater Conditions (§ 354.16) CD O O �OS,. • 0• 7 000 O� O 0, � �,,_//la• Po h i 16 .� 101 OD O CP Q O z } i 6 •_ i 2 r 6 ` 1990 1995 2000 2005 2020 2015 zoxo AN— "s 14 3 r � ! r•�r r c � k P 2 t� ' •,� 0 36 1990 1995 2000 2005 2010 2015 2020 t c la �� = 12 10 Ma=10 ing I 40 TTUPI z _ �� no ``■ 1990 1995 2090 20os 2010 2035 202c � I / ' J Explanation 16 ` r4AV& Nitrate Concentration (mg/L) E6 '�'r • 0-5.0 MCL=10m I s 9 �"t. O 5.0 - 7.5 _ s •� v 4 �� It 16 O 7.5-10 a� 14 ram' , dO 1 12 I � u r , � 10 MCL=tom 7 • 10 - 15 1990 1995 MW 2005 2010 2015 2020 ' r _ >15 r! ,,..��� : 14 All Other Features 2 9 Q San Luis Obispo Valley Basin _ _ _-'r 1990 1995 20M 2005 2010 2015 2020 t "re [ J City Boundary 16 $ r 0' /�/ Major Road 12 1/ MCL=101 10 m Watercourse Waterbody s4 r z 2yiL�/s�//jj,]�Y • 01990 1995 MW 2005 2010 2015 2020 TANK FARM- JJ���YYY��- J�1j J O ® O O DO O O • .9 O hr'Y1v1. O • O � o nV© N HAD o�r� • 12 e a � 6 � 4 2 19% 1995 20M 2005 2010 2015 2020 P.t CZI'FIC OCEA'A" P I S M o \ Prepared for: Author* AB Date: 1/16/2020 N A 0 0.25 0.5 1 Miles References: 1. Coordinate System: NAD SYatePlane Cal'rfornia V RIPS O405 Feet Projection: Lambert Conformalal Conic Datum: North American 1983 2.San Luis Obispo County 0 0.425 0.85 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP ,■,^\\``` �K'lometem O-e" aC oc10 c 6 10 mcl- lo -9 1�'. 8 r z 2 \.+1 f C' 1990 1995 2000 2005 2010 2015 2020 INS .Cr= •J1 i� I ' 1 too ' • � I 16 a: 122 110 Y y E MCL 10 m • $CC 10 4 GN R� 2 V '1 1990 1995 2000 2005 2010 2015 2020 Q e CYCC� 9rr yn Gr9r� Distribution of Nitrate in Basin Figure 5-17 Page 220 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5.9.3.3 Arsenic Groundwater Conditions (§ 354.16) Arsenic is also a common contaminant in California groundwater. Although it does occur naturally at low concentrations, elevated levels of arsenic in groundwater may be associated with pesticide use, mining activities, and release of industrial effluent. Arsenic has a Primary Drinking Water Standard with an MCL of 10 ug/I. Overall, arsenic concentrations ranged from below the detection limit to 28 ug/I, with an average value of 2.5 ug/I and a median value of 2 ug/I. Figure 5-19 presents occurrences and trends for arsenic in the Basin groundwater from wells with the most arsenic analytical data over time. The color -coded symbols represent the average result if multiple samples are documented. Wells screened in the bedrock aquifers may be expected to have higher natural arsenic concentrations than wells screened in Basin sediments due to increased degrees of mineralization in these waters. Most of the chemographs displayed show stable or decreasing concentrations of arsenic over the data period of record. (Graph number 1 shows a slight increase over time, but is still below the MCL). Sustainability projects and management actions implemented as part of this GSP are not anticipated to directly cause arsenic concentrations in groundwater in a well that would otherwise remain below the MCL to increase above the MCL. FM Page 221 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO rr \ •2 � 22.s A � j 2l1 1 e 11.5 e 1s c Izs 10 MCL .111 u 7.5 c s a 2.s a 1990 1995 2000 3005 2010 M15 2020 O 00 Groundwater Conditions (§ 354.16) 0 ti�_ .+ `•� 101 moo G zz.s f 17.5 r� MCL l0u 1.5 Y �Q 2.5 ysy ft 41I 1990 3995 2000 2001 2010 2011 2020 J zs 22.s O ff ; Io J aR�UI~ • l 1- lip ti 12.5 MCL l0u I 1990 1995 2000 Z005 2010 W15 2021 r' I PACIFIC OCE:I \" ��r� B E A C H IS I =22.5 1�� 5 y m OVOI 0, 20 c 12.o ae L Af e 10 MCL-l0u I F- 8 I.s� 5 < zs0 • •' 1990 1995 2000 ZOOS ZO10 W15 2020 ------- } ® ANK FARM RD O O ` O _ �.s 25 - V c 2 20 4 2 zo e ss e 12.5 10 MCL =10u 1 �4 8 2.5 s _ 2.5 J 0 1"0 1995 200 02005 2010 W15 2020 c 20 Prepared for: Author* AS Date: 111-020 N1. A 0 0.25 0.5 1 Miles References: Coordinate System: NAD 1983 StatePlane Cal'rfornia V RIPS O405 Feet Projection: Lambert Conformal Conic 1983 Datum: North American n Luis Obispo County 2.Sa 0 0.425 0.85 N 1.7 3. USGS SAN LUIS OBISPO VALLEY BASIN GSP �K'lometers 111111•I!!! !lr01!! !!, _!! !m!!! !!!!!! !!!!!! !llw�+�r�Rn r.. Explanation Arsenic Concentration (uglL) • 0-2.5 O 2.5 - 5.0 O 5.0 - 7.5 O 7.5 - 10 • >10 atu res is Obispo Valley Basin lundary Road ourse ,ody r ! d. 1 i 0, !' 2 !!!I!! !l11m1 nm lmmbgil! r � � !ram!! !!!!o mmmwrAa Milli Distribution of Arsenic in Basin Figure 5-18 Page 222 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5.9.3.4 Boron Groundwater Conditions (§ 354.16) Boron is an unregulated constituent and therefore does not have a regulatory standard. However, boron is a constituent of concern because elevated boron concentrations in water can damage crops and affect plant growth. Boron has been detected at concentrations greater than its RWQCB Basin Objective of 200 micrograms per liter (ug/1). Boron water quality results ranged from non -detect to 2,500 ug/l with an average of 0.16 ug/I and a median value of 0.12. Boron concentrations in the Alluvial Aquifer have been relatively consistent throughout the period of record. Boron concentrations in the Paso Robles Formation Aquifer have generally remained steady or declined slightly over the period of record. Sustainability projects and management actions implemented as part of this GSP are not anticipated to directly cause boron concentrations in groundwater in a well to increase. 5.9.3.5 Other Constituents Other constituents found in exceedance of their respective regulatory standard include arsenic, iron, gross alpha, manganese, selenium, and sulfate. Each of these exceedances occurred in samples from a small number of wells, indicating isolated occurrences of these elevated constituent concentrations rather than widespread occurrences, affecting the entire Basin. Isolated concentrations of arsenic, iron, gross alpha, and sulfate in the Basin have been relatively consistent throughout the period of record. Selenium concentrations have generally declined since 2007. There are not enough data to determine the trend of the elevated manganese concentrations in the Basin. Sustainability projects and management actions implemented as part of this GSP are not anticipated to directly cause concentrations of any of these constituents in groundwater to increase. 11NDIyAI'll DI►[MDf.7 Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. City of San Luis Obispo. 2016.2015 Urban Water Management Plan. 2016. —. 2018. General Plan. 2018. —. 2015. Water Resources Status Report. 2015. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. —. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. —. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. —. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. 47 Page 223 of 1183 SLO Basin Groundwater Sustainability Plan Groundwater Conditions (§ 354.16) County of SLO and City of SLO -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study. September. 1994. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. Hall, C.A. 1979. Geologic map of the San Luis Obispo - San Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. -. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.l.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. M., Page 224 of 1183 Draft Groundwater Sustainability Plan Chapter 6 — Water Budget forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by WATER SYSTEMS CONSULTING, INC. CHG %sul G`I Contants V StiilWater Sciences WaterSalutions,Inc. 6/25/2020 Page 225 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO TABLE OF CONTENTS Table of Contents Table of Contents Listof Figures................................................................................................................................................. i Tables........................................................................................................................................................... iv Appendices.................................................................................................................................................... v Listof Terms Used........................................................................................................................................ vi ExecutiveSummary.......................................................................................................................................1 Introduction to the SLO Basin GSP......................................................................................................... 1.1 Purpose of the Groundwater Sustainability Plan............................................................................ 1.2 Description of SLO Basin................................................................................................................. 1.3 Basin Prioritization.......................................................................................................................... 2 Agency Information (§ 354.6)................................................................................................................ 2.1 Agencies Names and Mailing Addresses......................................................................................... 2.2 Agencies Organization and Management Structures..................................................................... 2.2.1 County of San Luis Obispo....................................................................................................... 2.2.2 City of San Luis Obispo............................................................................................................ 2.2.3 Other Participating Parties in the MOA.................................................................................. 2.2.3.1 Edna Valley Growers Mutual Water Company............................................................... 2.2.3.2 Varian Ranch Mutual Water Company........................................................................... 2.2.3.3 Edna Ranch Mutual Water Company.............................................................................. 2.2.3.4 Golden State Water Company........................................................................................ 2.3 Authority of Agencies...................................................................................................................... 2.3.1 Groundwater Sustainability Agencies..................................................................................... 2.3.1.1 County of San Luis Obispo............................................................................................... 2.3.1.2 City of San Luis Obispo.................................................................................................... 2.3.2 Memorandum of Agreement.................................................................................................. 2.3.3 Coordination Agreements....................................................................................................... 2.4 Contact information for Plan Manager........................................................................................... 3 Description of Plan Area (§ 354.8)......................................................................................................... 3.1 SLO Basin Introduction.................................................................................................................... 3.2 Adjudicated Areas........................................................................................................................... 3.3 Jurisdictional Areas......................................................................................................................... 3.3.1 Federal Jurisdictions................................................................................................................ 3.3.2 Tribal Jurisdiction.................................................................................................................... i Page 226 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.3.3 State Jurisdictions................................................................................................................... 3.3.4 County Jurisdictions................................................................................................................ 3.3.5 City and Local Jurisdictions..................................................................................................... 3.3.6 Special Districts....................................................................................................................... 3.4 Land Use.......................................................................................................................................... 3.4.1 Water Source Types................................................................................................................ 3.4.2 Water Use Sectors................................................................................................................... 3.5 Density of Wells.............................................................................................................................. 3.6 Existing Monitoring and Management Programs........................................................................... 3.6.1 Groundwater Monitoring........................................................................................................ 3.6.1.1 Groundwater Level Monitoring..................................................................................... 3.6.1.2 Groundwater Quality Monitoring.................................................................................. 3.6.1.3 Surface Water Monitoring.............................................................................................. 3.6.1.4 Climate Monitoring......................................................................................................... 3.6.2 Existing Management Plans.................................................................................................... 3.6.2.1 SLO Basin Characterization and Monitoring Well Installation ........................................ 3.6.2.2 San Luis Obispo County Master Water Report(2012).................................................... 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014)............. 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan (2016) ........................... 3.6.3 Existing Groundwater Regulatory Programs............................................................................ 3.6.3.1 Groundwater Export Ordinance (2015).......................................................................... 3.6.3.2 Well Ordinances, County and City.................................................................................. 3.6.3.3 Countywide Water Conservation Program Resolution 2015-288 (2015) ....................... 3.6.3.4 Agricultural Order 133-2017-002 (2017).......................................................................... 3.6.3.5 Water Quality Control Plan for the Central Coast Basins (2017).................................... 3.6.3.6 California DWR Well Standards (1991)........................................................................... 3.6.3.7 Requirements for New Wells(2017)............................................................................... 3.6.3.8 Title 22 Drinking Water Program(2018)......................................................................... 3.6.3.9 Waterway Management Plan — San Luis Obispo Creek Watershed (2003).................... 3.6.3.10 Incorporation Into GSP.................................................................................................... 3.6.3.11 Limits to Operational Flexibility...................................................................................... 3.7 Conjunctive Use Programs.............................................................................................................. 3.8 Land Use Plans................................................................................................................................ 3.8.1 City of San Luis Obispo General Plan...................................................................................... 3.8.2 County of San Luis Obispo General Plan................................................................................. ii Page 227 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.8.3 Los Ranchos/Edna Village Plan................................................................................................ 3.8.4 Plan Implementation Effects on Existing Land Use................................................................. 3.8.5 Plan Implementation Effects on Water Supply....................................................................... 3.8.6 Well Permitting....................................................................................................................... 3.8.7 Land Use Plans Outside of Basin............................................................................................. 3.9 Management Areas......................................................................................................................... 3.9.1 Reason for Creation................................................................................................................ 3.10 Additional GSP Elements, if Applicable........................................................................................... 4 Basin Setting (§ 354.14)......................................................................................................................... 4.1 Basin Topography and Boundaries................................................................................................. 4.2 Primary Users of Groundwater....................................................................................................... 4.3 Soils Infiltration Potential................................................................................................................ 4.4 Regional Geology............................................................................................................................ 4.4.1 Regional Geologic Structures.................................................................................................. 4.4.2 Geologic Formations within the Basin.................................................................................... 4.4.2.1 Alluvium.......................................................................................................................... 4.4.2.2 Paso Robles Formation................................................................................................... 4.4.2.3 Pismo Formation............................................................................................................. 4.4.3 Geologic Formations Surrounding the Basin.......................................................................... 4.4.3.1 Monterey Formation....................................................................................................... 4.4.3.2 Obispo Formation........................................................................................................... 4.4.3.3 Franciscan Assemblage................................................................................................... 4.5 Principal Aquifers and Aquitards.................................................................................................... 4.5.1 Cross Sections......................................................................................................................... 4.5.2 Aquifer Characteristics............................................................................................................ 4.5.3 Aquitards................................................................................................................................. 4.6 Surface Water Bodies...................................................................................................................... 4.7 Subsidence Potential....................................................................................................................... 5 Groundwater Conditions (§ 354.16)...................................................................................................... 5.1 Groundwater Elevations and Intepretation.................................................................................... 5.1.1 Fall 1954 Groundwater Elevations.......................................................................................... 5.1.2 Spring 1990 Groundwater Elevations..................................................................................... 5.1.3 Modeled 1990s Groundwater Elevations............................................................................... 5.1.4 Spring 1997 Groundwater Elevations..................................................................................... 5.1.5 Spring 2011 Groundwater Elevations..................................................................................... Page 228 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 5.1.6 Spring 2015 Groundwater Elevations..................................................................................... 5.1.7 Spring 2019 Groundwater Elevations..................................................................................... 5.1.8 Fall 2019 Groundwater Elevations.......................................................................................... 5.1.9 Changes in Groundwater Elevation........................................................................................ 5.1.10 Vertical Groundwater Gradients............................................................................................. 5.2 Groundwater Elevation Hydrographs............................................................................................. 5.3 Groundwater Recharge and Discharge Areas................................................................................. 5.3.1 Groundwater Recharge Areas................................................................................................. 5.3.1.1 Infiltration of Precipitation............................................................................................. 5.3.1.2 Subsurface Inflow............................................................................................................ 5.3.1.3 Percolation of Streamflow.............................................................................................. 5.3.1.4 Anthropogenic Recharge................................................................................................ 5.3.2 Groundwater Discharge Areas................................................................................................ 5.4 Change in Groundwater Storage..................................................................................................... 5.5 Seawater Intrusion.......................................................................................................................... S.6 Subsidence...................................................................................................................................... 5.7 Interconnected Surface Water........................................................................................................ 5.7.1 Depletion of Interconnected Surface Water........................................................................... 5.8 Potential groundwater dependent ecosystems.............................................................................. 5.8.1 Hydrology................................................................................................................................ 5.8.1.1 Overview of GDE Relevant Surface and Groundwater Hydrology .................................. 5.8.1.2 Losing and Gaining Reaches............................................................................................ 5.8.2 Vegetation and Wetland Groundwater Dependent Ecosystem Identification ....................... 5.8.3 Identification of Special -Status Species and Sensitive Natural Communities Associates withGDE's.............................................................................................................................................. 5.9 Groundwater Quality Distribution and Trends............................................................................... 5.9.1 Groundwater Quality Suitability for Drinking Water.............................................................. 5.9.2 Distribution and Concentrations of Point Sources of Groundwater Constituents ................. 5.9.3 Distribution and Concentrations of Diffuse or Natural Groundwater Constituents ............... 5.9.3.1 Total Dissolved Solids...................................................................................................... 5.9.3.2 Nitrate............................................................................................................................. 5.9.3.3 Arsenic............................................................................................................................. 5.9.3.4 Boron............................................................................................................................... 5.9.3.5 Other Constituents.......................................................................................................... iv Page 229 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 6 Water Budget (§ 354.18)......................................................................................................................2 6.1 Climate........................................................................................................................................17 6.1.1 Historical Climate/Base Period...........................................................................................17 6.2 Water Budget Data Sources........................................................................................................22 6.3 Historical Water Budget..............................................................................................................22 6.3.1 Historical Time Period.........................................................................................................22 6.3.2 Historical Land Use..............................................................................................................23 6.3.3 Historical Surface Water Budget.........................................................................................26 6.3.4 Historical Groundwater Budget..........................................................................................33 6.3.5 Total Groundwater in Storage............................................................................................44 6.3.6 Change in Storage...............................................................................................................49 6.3.7 Sustainable Yield.................................................................................................................52 6.3.8 Quantification of Overdraft (Historical)..............................................................................53 6.4 Current Water Budget.................................................................................................................53 6.5 Projected Water Budget............................................................................................................. 64 6.5.1 Assumptions........................................................................................................................64 6.5.2 Inflows ................................................................................................................................. 64 6.5.3 Outflows..............................................................................................................................64 6.5.4 Change In Storage...............................................................................................................64 6.5 Projected Water Budget................................................................................................................. 6.5.1 Assumptions............................................................................................................................ 6.5.2 Inflows..................................................................................................................................... 6.5.3 Outflows.................................................................................................................................. J.5.4 1 Change In Storage................................................................................................................... 7 Sustainable Management Criteria (§ 354.22-30)................................................................................... 7.1 Sustainability Goal........................................................................................................................... 7.2 Process for Establishing Sustainable Management Criteria........................................................... 7.2.1 Minimum Thresholds.............................................................................................................. 7.2.2 Measurable Objectives........................................................................................................... 7.2.3 Undesirable Results................................................................................................................. 7.3 Chronic Lowering of Groundwater Levels Sustainability Indicator ................................................. 7.3.1 Locally Defined Undesirable Results....................................................................................... 7.3.2 Minimum Thresholds and Measurable Objectives................................................................. 7.3.3 Relation to Other Sustainability Indicators............................................................................. v Page 230 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 7.4 Change in Storage Sustainability Indicator..................................................................................... 7.4.1 Locally Defined Undesirable Results....................................................................................... 7.4.2 Minimum Thresholds.............................................................................................................. 7.4.3 Measurable Objectives........................................................................................................... 7.4.4 Relation to Other Sustainability Indicators............................................................................. 7.5 Seawater Intrusion Sustainability Indicator.................................................................................... 7.5.1 Locally Defined Undesirable Results....................................................................................... 7.5.2 Minimum Thresholds.............................................................................................................. 7.5.3 Measurable Objectives........................................................................................................... 7.5.4 Relation to Other Sustainability Indicators............................................................................. 7.6 Degraded Water Quality Sustainability Indicator........................................................................... 7.6.1 Locally Defined Undesirable Results....................................................................................... 7.6.2 Minimum Thresholds.............................................................................................................. 7.6.3 Measurable Objectives........................................................................................................... 7.6.4 Relation to Other Sustainability Indicators............................................................................. 7.7 Subsidence Sustainability Indicator................................................................................................ 7.7.1 Locally Defined Undesirable Results....................................................................................... 7.7.2 Minimum Thresholds.............................................................................................................. 7.7.3 Measurable Objectives........................................................................................................... 7.7.4 Relation to Other Sustainability Indicators............................................................................. 7.8 Depletion of Interconnected Surface Water Sustainability Indicator ............................................. 7.8.1 Locally Defined Undesirable Results....................................................................................... 7.8.2 Minimum Thresholds.............................................................................................................. 7.8.3 Measurable Objectives........................................................................................................... 7.8.4 Relation to Other Sustainability Indicators............................................................................. 7.9 Management Areas......................................................................................................................... 7.9.1 Minimum Thresholds and Measurable Objectives................................................................. 7.9.2 Monitoring and Analysis......................................................................................................... 7.9.3 Explanation of How Operation of Management Area Will Avoid Undesirable Results.......... 8 Monitoring Networks (§ 354.34)............................................................................................................ 8.1 Monitoring Objectives.................................................................................................................... 8.2 Monitoring Network....................................................................................................................... 8.2.1 Chronic Lowering of Groundwater Levels............................................................................... 8.2.2 Reduction of Groundwater Storage........................................................................................ 8.2.3 Seawater Intrusion.................................................................................................................. vi Page 231 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 8.2.4 Groundwater Quality.............................................................................................................. 8.2.5 Land Subsidence...................................................................................................................... 8.2.6 Depletion of Interconnected Surface Water........................................................................... 8.3 Groundwater Monitoring Protocol................................................................................................. 8.4 Data Management System.............................................................................................................. 8.5 Assessment and Improvement of Monitoring Network................................................................. 8.6 Annual Reports................................................................................................................................ 8.7 Periodic Evaluation by Agency........................................................................................................ 9 Projects and Management Actions (§ 354.44)....................................................................................... 9.1 Projects........................................................................................................................................... 9.1.1 Project A.................................................................................................................................. 9.2 Management Actions...................................................................................................................... 9.2.1 Management Action A............................................................................................................ 9.3 Projects Needed to Mitigate Overdraft.......................................................................................... 10 Implementation Plan.............................................................................................................................. 10.1 Cost of Implementation.................................................................................................................. 10.2 Funding Alternatives....................................................................................................................... 10.3 Implementation Schedule............................................................................................................... 10.4 GSP Annual Reporting..................................................................................................................... 10.5 Periodic Evaluations of GSP............................................................................................................ 11 Notice and Communications (§ 354.10)................................................................................................. 11.1 Communications and Engagement Plan......................................................................................... 11.2 Nature of Consultations.................................................................................................................. 11.3 Public Meetings............................................................................................................................... 11.4 Incorporation of Feedback in Decision -Making Process................................................................. 11.5 Comments Received....................................................................................................................... 11.6 Responses to Comments................................................................................................................. 12 Interagency Agreements (§ 357.2-4)..................................................................................................... 12.1 Coordination Agreements............................................................................................................... 13 References.............................................................................................................................................. 14 Appendices............................................................................................................................................. The grey highlighted sections in the Table of Contents (TOC) indicate that the section has been previously released (Chapters 1 through 5) or will be released in the future (Chapters 7 through 14). The complete list of the anticipated TOC is presented to give the reader context as to how Chapter 6 — Water Budget, connects with the complete Groundwater Sustainability Plan. vii Page 232 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO LIST OF FIGURES List of Figures Figure 6-1: The Hydrologic Cycle. Source: Department of Water Resources (Water Budget BMP, 2016)...3 Figure 6-2: Components of the Water Budget. Source: Modified from Department of Water Resources (Water Budget BMP, 2016)...........................................................................................................................4 Figure 6-3: Water Budget Subareas..............................................................................................................5 Figure 6-4: Surface Water Budget — San Luis Valley Subarea.....................................................................11 Figure 6-5: Surface Water Budget — Edna Valley Subarea..........................................................................12 Figure 6-6: Surface Water Budget — Basin Total.........................................................................................13 Figure 6-7: Groundwater Budget — San Luis Valley Subarea......................................................................14 Figure 6-8: Groundwater Budget — Edna Valley Subarea...........................................................................15 Figure 6-9: Groundwater Budget — Basin Total..........................................................................................16 Figure 6-10: 1987-2019 Historical Base Period Climate............................................................................. Figure 6-11: Rainfall Correlation Cal Poly vs. Gas Company....................................................................... Figure 6-12: San Luis Obispo Valley Basin Irrigated Crops 2016................................................................. Figure 6-13: Basin Sub -watershed Areas and Isohyetals............................................................................ Figure 6-14: Runoff vs Rainfall Correlation for Subareas............................................................................ Figure 6-15: Rainfall vs Infiltration.............................................................................................................. Figure 6-16: Bedrock Subsurface Inflow Reaches....................................................................................... Figure 6-17: Consumptive Use of Applied Water....................................................................................... Figure 6-18: Groundwater Elevation Contours Spring 1986....................................................................... Figure 6-19: Groundwater Elevation Contours Spring 2019....................................................................... Figure 6-20: Storage Volume Grids............................................................................................................. Figure 6-21: Groundwater Storage Estimate Comparison for Basin Subareas ........................................... Figure 6-22: Historical and Current Average Annual Surface Water Budget — San Luis Valley Subarea.... Figure 6-23: Historical and Current Average Annual Surface Water Budget — Edna Valley Subarea......... Figure 6-24: Historical and Current Average Annual Surface Water Budget — Basin Total ........................ Figure 6-25: Historical and Current Average Annual Groundwater Budget — San Luis Valley Subarea...... Figure 6-26: Historical and Current Average Annual Groundwater Budget — Edna Valley Subarea.......... Figure 6-27: Historical and Current Average Annual Groundwater Budget — Basin Total .......................... 18 20 24 28 29 35 38 42 46 47 48 51 58 59 60 61 62 63 viii Page 233 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table 6-1: Historical Water Budget - San Luis Valley Subarea .................................. Table 6-2: Historical Water Budget - Edna Valley Subarea ....................................... Table 6-3: Historical Water Budget - San Luis Obispo Valley Groundwater Basin.... Table 6-4: Historical Base Period Rainfall................................................................. Table 6-5: Irrigated Agriculture Acreages................................................................. Table 6-6: Land Cover Acreages................................................................................ Table 6-7: Stream Outflow Comparison................................................................... Table 6-8: Minimum Rainfall for Infiltration............................................................. Table 6-9: Subsurface Inflow Estimates.................................................................... Table 6-10: Rural Residential Water Use.................................................................. Table 6-11: Consumptive Use of Applied Water ....................................................... Table 6-12: Subsurface Outflow Estimates............................................................... Table 6-13: Specific Yield Averages........................................................................... Table 6-14: Spring Groundwater Storage Estimates ................................................. Table 6-15: Change in Storage Comparison — Historical Base Period 1987 — 2019.. Table 6-16: Preliminary Sustainable Yield(AFY)....................................................... Table 6-17: Estimated Overdraft(AFY)..................................................................... Table 6-18: Current Water Budget - San Luis Valley Subarea ................................... Table 6-19: Current Water Budget - Edna Valley Subarea ........................................ Table 6-20: Current Water Budget - Basin Total ....................................................... Tables 8 9 ..... 25 ..... 26 ..... 33 ..... 36 ..... 37 ..... 41 ..... 43 ..... 44 ..... 45 ..... 49 ..... 50 ..... 52 ..... 53 ..... 55 ..... 56 ..... 57 ix Page 234 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES Appendices Page 235 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level Xi Page 236 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant xii Page 237 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 238 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (¢ 354.18) County of SLO and City of SLO 6 WATER BUDGET (§ 354.18) The purpose of a water budget is to provide an accounting and assessment of the total annual volume of groundwater and surface water entering and leaving the Basin, including historical, current, and projected water budget conditions, and the change in volume stored. Both numerical and analytical methods have been used during water budget preparations for the GSP. The analytical method as used in this document refers to application of the water budget equation and the inventory method using spreadsheets, with groundwater flow estimates based on Darcy's Law and change in storage calculations based on the specific yield method. Numerical methods refer to surface water and groundwater flow modeling, which provide a dynamic and more rigorous analysis of both surface -groundwater interactions and the impacts from pumping on groundwater in storage. The historical and current analytical groundwater budget will be used as part of the Basin conceptual model to prepare input estimates and provide a check for the numerical model, from which the projected water budget will be produced. This chapter presents the analytical water budget for the historical and current periods and the numerical model water budget for the projected future period. Once the numerical model water budget is calibrated, the results will be presented as comparisons to the analytical water budget. A water budget identifies and quantifies various components of the hydrologic cycle within a user - defined area, in this case the San Luis Obispo Valley groundwater Basin. Water circulates between the atmospheric system, land surface system, surface water bodies, and the groundwater system, as shown in Figure 6-1(DWR, 2016). The water budget equation used for the analytical method is as follows: INFLOW — OUTFLOW = CHANGE IN STORAGE Inflow is the sum of all surface water and groundwater entering the Basin and outflow is the sum of all surface water and groundwater leaving the Basin. The difference between total inflow and total outflow over a selected time period is equal to the change in total storage (surface water and groundwater) within the Basin over the same period. Components of inflow and outflow represented in the water budget are shown in Figure 6-2. Not all of the components shown are needed for the San Luis Obispo Valley Groundwater Basin GSP. A key using letters to represent components in this water budget has been added to Figure 6-2 for reference with the main water budget tables. Some components have been modified and renamed from the original DWR figure to better represent this specific water budget. The water budget equation given above is simple in concept, but it is challenging to measure and account for all the components of inflow and outflow within a Basin. Some of these components can be measured or estimated independently, while others are calculated using the water budget equation. The water budget for this GSP has been prepared for the two subareas that cover the Basin, the San Luis Valley subarea and the Edna Valley subarea (Figure 6-3). Subareas are not to be confused with subbasins, and are defined for this water budget analysis. They are then combined into a single water budget for the entire Basin. Both subarea water budgets and the Basin water budget are included herein. Surface water (combined atmospheric, land surface, and stream systems) and groundwater budgets have been prepared for each subarea and for the Basin. The subarea approach for water budget calculations follows the approach used by prior investigators (Boyle, 1991; DWR, 1997). 2 Page 239 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Atmosphere Pre i tation Evaporation �� rtVap0flaflSpira�i0n .ti narj Evaporation ated .I rlKtlture Diversion Canal r� Streamflaw } III Treatment Managed Recharge Basin l Plant Wetland Groundwater Table tlrlltra \ Injection Well Agricultural Supply Well Monitoring Wells Municipal llndusirial Confined Aquifer Supply Well Unconfined Aquifer Figure 6-1: The Hydrologic Cycle. Source: Department of Water Resources (Water Budget BMP, 2016) 3 Page 240 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO M+ Inflow to System M+ Outnow From System Intem6 Flaw Water Budget (§ 354.18) Atmospheric System Precipitation Evapo- Precipitation Evaporation Atranspiration Conveyance �"' User Defined Ar{:a Evaporation SW Inflow V L s outflow L ELossto Imported Water �x � Stream a V. Percolation _ Conveyance Reuss: 5aepage -- Loss to Unsaturated Zone' Wetland Lake Gain from Stream Infiltration Ir�flltralion GVN of Applied GWHank GWEx ° Of Preeip. Extraction UValc:r Extraction Subsurface Inflow Q Subsurface�Qutflow # u 0 UserDeimao 4rea ❑ Change in Storage Figure 6-2: Components of the Water Budget. Source: Modified from Department of Water Resources (Water Budget BMP, 2016) 2 Page 241 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) i ~ClaI�Poly NOAA CIMI So 5� . r , a r + C .r 1 Q. ♦ ��i o� Oil 00 M ,,w + , ♦ }J ' ,ter e � .� The Gas Company , if r———� J } .Ol Ol Bedrock High Subarea Boundary - r ,r 0. Prepared For: Nt, Author: TK ,1 Q Date 06/,25/2020 ,\\\\V 0�0.25 0.5 0.75 1 mi 0 0 SAN LUIS OBISPO VALLEY BASIN GSP m References: 1. Coordinate System: State Plane Calif o mia V FIPS O405 Feet 2. Projection_ Lambert Conformal Conic 3. Firozor�tal DatumFAD 83 4. Vertical Datum_ NAVD 88 5. Baseman. USGS 75' Topographic Map Notes: 1 Land use des gnatons from DVVR (2016), data obtained from gis water ca_gov 2. Turf area not'ncluded in DVVR (2016) dataset 3. Not all crops shown on figure are applicable to SLO Valley Groundwater Basin Explanation r-1 SLO Valley Groundwater Basin Boundary SLO City Limits 0+ Weather Stations Land Use C I CITRUS AND SUBTROPICAL D I DECIDUOUS FRUITS AND NUTS F I FIELD CROPS G I GRAIN AND HAY CROPS 0 IJIDLE PIPASTURE T I TRUCK NURSERY AND BERRY CROPS UIURBAN V I VINEYARD Y I YOUNG PERENNIAL 0 Turf z off 'I Fi ;i,+ i Y4 Water Budget Subareas Figure 6-3 5 Page 242 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO As presented in Chapter 4, there is a topographic high point in bedrock elevations underlying the Basin that creates a bedrock high between the San Luis Valley and Edna Valley subareas (Figure 4-4). This bedrock high partially isolates the deeper portions of the Basin aquifers (Figure 4-5) and restricts underflow between the two subareas. Figure 6-3 shows the San Luis Valley and Edna Valley subareas used for the water budget, with the subarea boundary located along Hidden Springs Road. Note that the boundary between the subareas is shifted slightly to the west of the bedrock high (Figure 6-3) in order to better correlate with overlying land use. Land use for 2016 (DWR, 2016) is shown on the map to help illustrate differences across the subarea boundary. Immediately west of the subarea boundary is rural residential land and the County airport. To the east of the subarea boundary are residential subdivisions, a golf course, and irrigated agricultural lands. The two subareas of the Basin are hydrologically distinct, as evidenced by the differences in watershed area (Figure 3-10), sediment thickness (Figure 4-4), and water level hydrographs (Figure 5-11). The groundwater budgets are also very different between the subareas, and separating the two is necessary to properly characterize the Basin. The two subarea water budgets have also been combined to create a total Basin water budget. The San Luis Valley subarea is 6,773 acres (10.6 square miles), and the Edna Valley subarea is 5,948 acres (9.3 square miles), with a total Basin area of 12,271 acres (19.2 square miles). The San Luis Valley subarea receives surface inflow from a watershed of 28,823 acres (45 square miles) and the Edna Valley subarea receives surface inflow from a watershed of 10,145 acres (15.9 square miles). The watershed divide between San Luis Obispo Creek and Pismo Creek is not coincident with the bedrock high or subarea boundary, and watershed area draining to Davenport Creek in the Edna Valley subarea is part of the San Luis Obispo Creek watershed (Figure 3-10; Chapter 3). Table 6-1, Table 6-2, and Table 6-3 present the historical surface water and groundwater budgets for the San Luis Valley subarea, the Edna Valley subarea, and the Basin total, respectively. Bar graphs are included in Figure 6-4 through Figure 6-9. The three main water budget tables contain a detailed accounting of the water budget for the Basin and will be referred to throughout this chapter. A letter key has been added to provide a visual reference with Figure 6-3. Note that Figure 6-3 breaks the water budget into four components (atmospheric system, land surface system, river & stream system, and groundwater system). The atmospheric system transfers evaporation to precipitation and overlies the other systems. The land surface system is the portion of the water budget that includes land surface and the unsaturated zone extending to the top of the groundwater system. The rivers & streams system is the portion of the water budget that includes rivers, streams, conveyance facilities and diversion ditches, and lakes and reservoirs. The atmospheric, land surface, and river & streams water budgets for this Basins have been combined into a single surface water budget. As a result, not all the components in Figure 6-3 have corresponding budget items listed for the Basin. For example, the runoff and return flow components of the land surface system into the river & stream system in Figure 6-3 are part of the surface water outflow component (Labeled "L"). The six bar graphs are graphical representations of the water budget that allow quick comparisons of the various budget quantities, but are not individually referenced. Figure 6-4, Figure 6-5, and Figure 6-6 illustrate the surface water budget portions of Table 6-1, Table 6-2, and Table 6-3, while Figure 6-7, Figure 6-8, and Figure 6-9 illustrate the groundwater budget portions of the tables. Water budget climate, historical time period, methodology, sustainable yield, and overdraft interpretation are also presented in this chapter. Some general observations on the water budget are worth noting. First, the surface water budget for the two subareas shows similar patterns of increasing and decreasing total flow from year to year, which is expected given similar precipitation with somewhat proportional stream flow. The San Luis Valley subarea Page 243 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) surface water budget is close to double the Edna Valley surface water budget, however. This is due to a larger watershed area for the San Luis Valley subarea and to the significant volume of surface water imported by the City of San Luis Obispo. Secondly, the groundwater budget for the Edna Valley subarea shows high groundwater recharge events during all wet years, which is expected, while the San Luis Obispo shows a more attenuated response, with some wet years (1993, 2017) providing greater recharge than others. This is because during some wet years, the aquifers in the San Luis Valley subarea fill up to the point where there is no more available storage volume, and therefore no additional recharge occurs (also inferred by the relatively flat water level hydrographs in Figure 5-11). In 1993 and 2017, there was sufficient storage room following drought to allow greater recharge than during other wet years when the subarea was effectively full. 7 Page 244 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Table 6-1: Historical Water Budget - San Luis Valley Subarea. SURFACE WATER INFLOW (AF) SURFACE WATER OUTFLOW (AF) GROUNDWATER INFLOW (AF) GROUNDWATER OUTFLOW (AF) m G! i..� c O 41 fC a� iz a c O ++ a+ L d> V r_ O ++ L ++ Q v 3 p C v L N L w ++ v M , Qi M w '^ v ++ L N O _� Q .Q p. 3 uM LA 0 Z Q O C p `� f0 O ++ Q. W a -p C G! f0 _.0 p' L Q_j Q L p m W� O _ do Q' Q 0- L Q Qi p to W Y J W \ C M L -��, Q a� a ++ to f6 O w L I.A .> N .0 c O p C O ++ (� L .� +' a"i L C a v c (6 Q Q. L Q aF �� L r +; M C 3 v_ Q Q Q Q L a to C C p ++ H Q 1 L (�7 +� C 3 O 7 p aJ y H O J ~ O ~ .4- c O p C O a+ i+ Q +' '� :� CU v c c6 Q CL L Q L O �+ +� v_ Q CL Q Q L Q: O co +� p O 4r H w 1 L (�7 +U _ _o `_ i U U (0 L Z Q O O aI v i f6 L +' L W V O ++ c� fC dp L +' Q W v V O � C co N N U ,� 3 p of 41 3 3 O to H O J Q H O Q G/ dA fp C L R O t N U KEY A B B C D E F F F F/G H I J J K L I J J K M B B N O p 1987 7,720 10,080 7,850 6,790 9,450 410 430 660 2,180 2,350 1,300 1,750 1,580 1,850 1,790 6,410 9,660 3,600 2,140 5,790 5,520 5,320 4,070 1,970 2,520 8,490 8,180 6,020 1,280 1,960 29,850 35,420 23,780 16,210 23,860 7,450 8,540 7,550 6,660 8,250 2,850 2,780 2,180 1,200 1,460 1,050 1,410 1,270 1,490 1,440 740 780 380 410 380 5,520 5,320 4,070 1,970 2,520 220 1,260 250 110 980 530 520 430 290 320 260 350 310 370 350 1,090 1,640 610 360 980 10,150 12,840 6,730 3,360 7,160 29,860 35,440 23,780 16,220 23,840 220 1,260 250 110 980 530 520 430 290 320 260 350 310 370 350 1,090 1,640 610 360 980 340 340 340 340 340 2,440 4,110 1,940 1,470 2,970 410 430 660 2,180 2,350 1,300 1,750 1,580 1,850 1,790 1,050 1,320 1,130 1,250 1,190 120 120 120 120 120 2,880 3,620 3,490 5,400 5,450 -440 490 -1,550 -3,930 -2,480 1989 1990 199_ 199t 11,250 15,700 8,620 16,930 11,740 2,240 1,030 790 660 740 1,820 1,790 1,690 1,870 1,910 11,250 17,350 7,640 26,690 11,930 3,070 3,630 3,750 3,780 4,210 2,910 4,980 5,400 5,590 6,160 32,540 44,480 27,890 55,520 36,690 8,590 8,640 7,900 8,630 8,530 1,720 1,980 2,030 2,060 2,250 1,460 1,440 1,360 1,500 1,530 700 660 740 540 680 3,070 3,630 3,750 3,780 4,210 2,200 5,950 580 6,070 1,820 360 400 410 410 440 360 350 330 370 380 1,910 1,210 1,300 1,870 830 12,160 20,210 9,480 30,300 16,010 32,530 44,470 27,880 55,530 36,680 2,200 5,950 580 6,070 1,820 360 400 410 410 440 360 350 330 370 380 1,910 1,210 1,300 1,870 830 340 340 340 340 340 5,170 8,250 2,960 9,060 3,810 2,240 1,030 790 660 740 1,820 1,790 1,690 1,870 1,910 1,090 1,190 1,090 1,110 1,040 120 120 120 120 120 51270 4,130 3,690 3,760 3,810 -100 4,120 -730 5,300 0 1993 1994 1995 1996 1997 15,930 16,930 8,670 12,620 12,470 780 680 660 670 710 2,280 1,870 2,510 1,810 1,740 17,670 26,460 7,720 13,130 12,920 4,400 4,150 4,350 4,410 4,250 6,440 6,130 6,470 6,560 6,270 47,500 56,220 30,380 39,200 38,360 8,580 8,580 7,870 8,530 8,570 2,370 2,230 2,340 2,360 2,290 1,830 1,500 2,020 1,450 1,400 690 520 810 670 670 4,400 4,150 4,350 4,410 4,250 2,690 1,770 650 2,950 1,590 460 440 450 450 440 450 370 500 360 340 530 790 1,310 920 900 25,510 35,880 10,100 17,090 17,900 47,510 56,230 30,400 39,190 38,350 2,690 1,770 650 2,950 1,590 460 440 450 450 440 450 370 500 360 340 530 790 1,310 920 900 340 340 340 340 340 4,470 3,710 3,250 5,020 3,610 780 680 660 670 710 2,280 1,870 2,510 1,810 1,740 1,290 1,040 1,330 1,040 1,040 120 120 120 120 120 41470 3,710 4,620 3,640 3,610 0 0 -1,370 1,380 0 1998 1999 2nf, 2002 7,510 11,630 8,140 15,120 13,180 630 610 620 620 610 1,850 1,470 1,500 1,370 1,280 6,130 11,780 6,990 16,560 6,500 4,530 4,610 4,340 5,390 4,950 6,340 6,300 6,740 6,250 6,280 26,990 36,400 28,330 45,310 32,800 7,240 8,640 7,780 8,720 8,710 2,000 1,860 2,560 1,040 1,500 1,490 1,180 1,200 1,100 1,030 770 680 760 600 660 4,530 4,610 4,340 5,390 4,950 220 2,490 300 1,850 1,580 440 440 460 440 440 360 290 290 270 250 1,040 820 1,190 1,160 450 8,900 15,390 9,450 24,730 13,220 26,990 36,400 28,330 45,300 32,790 220 2,490 300 1,850 1,580 440 440 460 440 440 360 290 290 270 250 1,040 820 1,190 1,160 450 340 340 340 340 340 2,400 4,380 2,580 4,060 3,060 630 610 620 620 610 1,850 1,470 1,500 1,370 1,280 1,140 1,040 1,140 950 1,050 120 120 120 120 120 3,740 3,240 3,380 3,060 3,060 -1,340 1,140 -800 1,000 0 2004 2005 2001 2007 4,340 7,800 5,890 11,980 16,930 610 520 560 580 530 1,510 1,550 1,430 1,160 1,260 6,140 11,030 7,670 22,860 21,360 4,200 4,010 3,930 4,160 4,480 6,840 6,730 6,580 5,860 5,530 23,640 31,640 26,060 46,600 50,090 4,330 7,540 5,840 8,680 8,750 2,770 2,770 2,740 1,850 1,170 1,210 1,250 1,150 940 1,020 840 790 790 650 610 4,200 4,010 3,930 4,160 4,480 0 210 40 2,590 1,400 480 470 480 450 430 290 300 280 220 240 1,040 1,870 1,300 1,600 640 8,440 12,410 9,500 25,460 31,350 23,600 31,620 26,050 46,600 50,090 0 210 40 2,590 1,400 480 470 480 450 430 290 300 280 220 240 1,040 1,870 1,300 1,600 640 340 340 340 340 340 2,150 3,190 2,440 5,200 3,050 610 520 560 580 530 1,510 1,550 1,430 1,160 1,260 1,250 1,260 1,140 960 1,150 120 120 120 120 120 3,490 3,450 3,250 2,820 3,060 -1,340 -260 -810 2,380 -10 2008 2009 2010 2011 2012 8,470 5,290 5,220 5,960 10,150 530 510 540 400 400 1,420 1,790 1,560 1,680 1,690 5,430 3,670 3,270 1,620 4,850 3,950 4,060 3,660 3,420 3,550 5,770 6,330 6,190 5,750 5,490 25,570 21,650 20,440 18,830 26,130 7,940 5,260 5,190 5,900 8,490 1,910 2,320 2,620 2,300 1,920 1,150 1,450 1,260 1,360 1,360 770 430 420 410 730 3,950 4,060 3,660 3,420 3,550 430 30 20 50 1,350 450 470 470 440 430 270 340 300 330 330 920 620 560 270 820 7,770 6,670 5,940 4,340 7,130 25,560 21,650 20,440 18,820 26,110 430 30 20 50 1,350 450 470 470 440 430 270 340 300 330 330 920 620 560 270 820 340 340 340 340 340 2,410 1,800 1,690 1,430 3,270 530 510 540 400 400 1,420 1,790 1,560 1,680 1,690 1,200 1,350 1,290 1,270 1,170 120 120 120 120 120 3,270 3,770 3,510 3,470 3,380 -860 -1,970 -1,820 -2,040 -110 2013 2014 2015 2016 2017 16,930 6,980 15,040 400 400 400 1,550 1,190 1,030 18,450 2,630 16,360 4,400 3,330 4,360 5,370 5,790 5,080 47,100 20,320 42,270 8,730 6,870 8,800 960 2,430 720 1,250 970 830 590 800 630 4,400 3,330 4,360 6,910 90 4,430 440 450 420 300 230 200 550 180 490 22,970 4,970 21,400 47,100 20,320 42,280 6,910 90 4,430 440 450 420 300 230 200 550 180 490 340 340 340 8,540 1,290 5,880 400 400 400 1,550 1,190 1,030 1,260 1,270 1,070 120 120 120 3,330 2,980 2,620 5,210 -1,690 3,260 2018 2019 Type Year: Dry / elow Normal / 4bove Norn / Wei AF = Acre -Feet; KEY = Referenced Components on Figure 6-3 F3 Page 245 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Table 6-2: Historical Water Budget - Edna Valley Subarea. SURFACE WATER INFLOW (AF) SURFACE WATER OUTFLOW (AF) GROUNDWATER INFLOW (AF) GROUNDWATER OUTFLOW (AF) v y 41 f6 o +, Q .V GJ a 0 L c0 ++ N _ V 0 i ++ Q N .... 0 GJ + z J Q ~ 0 O 4+ F" Q. Uj �U N a` Mw M _ Q. L CL Q .� 4- N O ++ H MG, _ Q Q. a L Q G1 `� O H uw rG 'L m Q c c ° +� +, +� (C Q 41 'Gd G1 - L �' c°o a Q � a� �� ° GJ +; ++ M a a Q L Q: ° f�6 4J ° ° cn L7 1 fC L W C7 ++ ° � O E co i 41 O J Q H ° o ° rZ 0 +� i+ L Q. �+ V N - L a c°o a -0 Q D tF �� L ° G1 4.; ++ M 3 a Q Q L �% ° f�0 +; 3 ° O Vf :.i M L CU V' ++ � i6 L z � Q O o_ u C f6 (0 �"L {JJ .... o v_ lG 41 Q LJJ a, 3 L ° 7 H ++ M 7 O O Q H Q - GJ G) OA dA cG r L f6 0 s V N KEY A B B C F F F F I J J K L I J J K M B B O P 1987 6,780 8,860 6,900 5,960 8,300 630 760 640 740 760 2,450 2,750 2,670 3,040 2,810 2,150 3,240 1,210 730 1,940 12,010 15,610 11,420 10,470 13,810 6,610 7,970 6,670 5,860 7,550 450 560 470 530 530 2,000 2,240 2,190 2,490 2,300 40 40 20 20 20 140 660 180 90 570 190 210 180 220 240 440 510 480 550 510 300 450 170 100 270 1,840 2,960 1,070 620 1,840 12,010 15,600 11,430 10,480 13,830 140 660 180 90 570 190 210 180 220 240 440 510 480 550 510 300 450 170 100 270 110 110 110 110 110 1,180 1,940 1,120 1,070 1,700 630 760 640 740 1 760 2,450 2,750 2,670 3,040 2,810 100 100 100 100 100 3,180 3,610 3,410 3,880 3,670 -2,000 -1,670 -2,290 -2,810 -1,970 1988 1989 1990 1991 1992 9,880 13,780 7,570 14,870 10,310 790 840 760 820 850 2,810 2,710 2,640 2,820 3,000 3,770 5,810 2,560 8,930 3,990 17,250 23,140 13,530 27,440 18,150 8,030 8,000 7,050 7,930 7,880 530 570 500 550 550 2,300 2,220 2,170 2,320 2,470 40 40 40 40 40 1,460 4,800 400 5,740 1,920 270 290 270 280 310 510 490 470 500 530 530 810 360 1,250 560 3,590 5,940 2,280 8,840 3,900 17,260 23,160 13,540 27,450 18,160 1,460 4,800 400 5,740 1,920 270 290 270 280 310 510 490 470 500 530 530 810 360 1,250 560 110 110 110 110 110 2,880 6,500 1,610 7,880 3,430 790 840 760 820 850 2,810 2,710 2,640 2,820 3,000 100 100 100 100 100 3,700 3,650 3,500 3,740 3,950 -820 2,850 -1,890 4,140 -520 1993 1994 1995 199 1997 13,990 14,870 7,620 11,080 10,950 1,030 860 1,020 940 980 3,460 3,000 3,720 2,700 3,320 5,910 9,730 2,590 4,400 4,330 24,390 28,460 14,950 19,120 19,580 7,840 7,790 6,990 7,710 7,670 690 570 690 600 630 2,850 2,480 3,070 2,230 2,750 40 40 40 40 40 5,010 5,750 470 2,650 2,550 350 300 340 350 360 610 520 650 480 570 830 1,360 360 620 610 6,190 9,660 2,340 4,470 4,400 24,410 28,470 14,950 19,150 19,580 5,010 5,750 470 2,650 2,550 350 300 340 350 360 610 520 650 480 570 830 1,360 360 620 610 110 110 110 110 110 6,910 8,040 1,930 4,210 4,200 1,030 860 1,020 940 980 3,460 3,000 3,720 2,700 3,320 100 100 100 100 100 4,590 3,960 4,840 3,740 4,400 2,320 4,080 -2,910 470 -200 1998 1999 2000 2001 2002 6,600 10,220 7,150 13,280 11,570 960 870 970 840 900 3,220 3,030 31040 2,870 3,040 2,060 3,950 2,340 5,540 2,180 12,840 18,070 13,500 22,530 17,690 6,400 7,600 6,740 7,610 7,580 630 570 630 550 590 2,660 2,500 2,520 2,370 2,520 40 40 40 40 40 170 2,000 320 4,450 3,100 340 320 350 300 320 570 520 530 500 530 290 550 330 780 310 1,760 3,970 2,070 5,930 2,730 12,860 18,070 13,530 22,530 17,720 170 2,000 320 4,450 3,100 340 320 350 300 320 570 520 530 500 530 290 550 330 780 310 110 110 110 110 110 1,480 3,500 1,640 6,140 4,370 960 870 970 840 900 3,220 3,030 3,040 2,870 3,040 100 100 100 100 100 4,280 4,000 4,110 3,810 4,040 -2,800 -500 -2,470 2,330 330 2003 2004 2005 200 2007 3,810 6,850 5,170 10,520 14,870 1,180 1,210 950 820 840 3,830 3,750 3,660 3,360 3,330 2,160 3,750 2,740 7,490 7,840 10,980 15,560 12,520 22,190 26,880 3,800 6,580 5,100 7,560 7,550 770 780 650 550 580 3,170 3,100 3,040 2,790 2,760 40 40 40 40 40 0 220 50 2,260 5,760 430 440 310 270 270 660 650 620 570 570 300 520 380 1,050 1,100 1,820 3,230 2,330 7,100 8,260 10,990 15,560 12,520 22,190 26,890 0 220 50 2,260 5,760 430 440 310 270 270 660 650 620 570 570 300 520 380 1,050 11100 110 110 110 110 110 1,500 1,940 1,470 4,260 7,810 1,180 1,210 950 820 840 3,830 3,750 3,660 3,360 3,330 100 100 100 100 100 5,110 5,060 4,710 4,280 4,270 -3,610 -3,120 -3,240 -20 3,540 2008 2009 2010 2011 2012 7,440 4,640 4,590 5,230 8,920 940 1,040 960 880 790 3,560 3,780 3,580 4,230 3,200 1,810 1,260 1,120 490 1,560 13,750 10,720 10,250 10,830 14,470 6,830 4,600 4,550 5,160 7,550 650 740 680 650 580 2,950 3,120 2,960 3,500 2,680 40 20 20 20 40 450 40 30 60 980 290 310 280 230 220 610 660 620 720 530 250 180 160 70 220 1,660 1,070 950 410 1,680 13,730 10,740 10,250 10,820 14,480 450 40 30 60 980 290 310 280 230 220 610 660 620 720 530 250 180 160 70 220 110 110 110 110 110 1,710 1,300 1,200 1,190 2,060 940 1,040 960 880 790 3,560 3,780 3,580 4,230 3,200 100 100 100 100 100 4,600 4,920 4,640 5,210 4,090 -2,890 -3,620 -3,440 -4,020 -2,030 2013 2014 2015 2016 2017 14,870 6,130 13,210 850 880 770 3,640 31550 3,350 6,240 650 5,480 25,600 11,210 22,810 7,570 6,020 7,630 640 650 580 3,030 2,960 2,800 40 40 40 5,730 90 4,370 220 240 210 610 590 550 870 90 770 6,890 540 5,870 25,600 11,220 22,820 5,730 90 4,370 220 240 210 610 590 550 870 90 770 110 110 110 7,540 1,120 6,010 850 880 770 3,640 3,550 3,350 100 100 100 4,590 4,530 4,220 2,950 -3,410 1,790 2018 2019 Type Year: Dry / n-l-, Nnrmni / Ahn. / Wet AF = Acre -Feet; KEY = Referenced Components on Figure 6-3 17 Page 246 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354,18) Table 6-3: Historical Water Budget - San Luis Obispo Valley Groundwater Basin SURFACE WATER INFLOW (GW) SURFACE WATER OUTFLOW (GW) GROUNDWATER INFLOW (GW) GROUNDWATER OUTFLOW (GW) aJ y = o ++ a L a c 0 2 M M c 0 ++ M tvD a axi 3 o ,0 H L a, ++ a °�D 3 to +� 67 tn v, °+,' i VI CL E _- - Q 3 :.i N o Z - J a O ~ _ O ,� +� O ++ a W '� i a tea, _ 0. Q a _' L `� M W 3 tea, _ _ b4 �. a Q i a `� W '� W M _ •L as co pC r ,� M aJ al a, > U ca 3 `� = 0 o = +� +_+ ns L ,� +� v - a v c ns Q a Q -- L 0 a, % c� v Q a a a i .� Qi 0 ++ c = p of cJ L /�/^� (U V = 3 0 +� O L N J H O `� = 0 o _ :� ++ M L .Q +_ V L - a v c m Q a a -- L 0 a� +, 4E3: v Q oA a a a i a, ++ 0 M +' c = O of U ns L /�I^^ 0 V C o = U fa L 3 N Z - J a F O o c L ca ++ L ii � C9 o L ++ a ii C9 W r = W co a, u i O , N ++ � 0 N O J a H O _ a al d0 oa ra = L �a �0, Vf KEY A B B C D E F F F F/G H I J J K L I J J K M B B N O P 1987 14,500 18,940 14,750 12,750 17,750 1,040 1,190 1,300 2,920 3,110 3,750 4,500 4,250 4,890 4,600 8,560 12,900 4,810 2,870 7,730 5,520 5,320 4,070 1,970 2,520 8,490 8,180 6,020 1,280 1,960 41,860 51,030 35,200 26,680 37,670 14,060 16,510 14,220 12,520 15,800 3,300 3,340 2,650 1,730 1,990 3,050 3,650 3,460 3,980 3,740 780 820 400 430 400 5,520 5,320 4,070 1,970 2,520 360 1,920 430 200 1,550 720 730 610 510 560 700 860 790 920 860 1,390 2,090 780 460 1,250 11,990 15,800 7,800 3,980 9,000 41,870 51,040 35,210 26,700 37,670 360 1,920 430 200 1,550 720 730 610 510 560 700 860 790 920 860 1,390 2,090 780 460 1,250 450 450 450 450 450 3,620 6,050 3,060 2,540 4,670 1,040 1,190 1,300 2,920 3,110 3,750 4,500 4,250 4,890 4,600 1,050 1,320 1,130 1,250 1,190 220 220 220 220 220 6,060 7,230 6,900 9,280 9,120 -2,440 -1,180 -3,840 -6,740 -4,450 19. 1989 1990 1991 21,130 29,480 16,190 31,800 22,050 3,030 1,870 1,550 1,480 1,590 4,630 4,500 4,330 4,690 4,910 15,020 23,160 10,200 35,620 15,920 3,070 3,630 3,750 3,780 4,210 2,910 4,980 5,400 5,590 6,160 49,790 67,620 41,420 82,960 54,840 16,620 16,640 14,950 16,560 16,410 2,250 2,550 2,530 2,610 2,800 3,760 3,660 3,530 3,820 4,000 740 700 780 580 720 3,070 3,630 3,750 3,780 4,210 3,660 10,750 980 11,810 3,740 630 690 680 690 750 870 840 800 870 910 2,440 2,020 1,660 3,120 1,390 15,750 26,150 11,760 39,140 19,910 49,790 67,630 41,420 82,980 54,840 3,660 10,750 980 11,810 3,740 630 690 680 690 750 870 840 800 870 910 2,440 2,020 1,660 3,120 1,390 450 450 450 450 450 8,050 14,750 4,570 16,940 7,240 3,030 1,870 1,550 1,480 1,590 4,630 4,500 4,330 4,690 4,910 1,090 1,190 1,090 1,110 1,040 220 220 220 220 220 8,970 7,780 7,190 7,500 7,760 -920 6,970 -2,620 9,440 -520 1993 1994 1995 19! 1997 29,920 31,800 16,290 23,700 23,420 1,810 1,540 1,680 1,610 1,690 5,740 4,870 6,230 4,510 5,060 23,580 36,190 10,310 17,530 17,250 4,400 4,150 4,350 4,410 4,250 6,440 6,130 6,470 6,560 6,270 71,890 84,680 45,330 58,320 57,940 16,420 16,370 14,860 16,240 16,240 3,060 2,800 3,030 2,960 2,920 4,680 3,980 5,090 3,680 4,150 730 560 850 710 710 4,400 4,150 4,350 4,410 4,250 7,700 7,520 1,120 5,600 4,140 810 740 790 800 800 1,060 890 1,150 840 910 1,360 2,150 1,670 1,540 1,510 31,700 45,540 12,440 21,560 22,300 71,920 84,700 45,350 58,340 57,930 7,700 7,520 1,120 5,600 4,140 810 740 790 800 800 1,060 890 1,150 840 910 1,360 2,150 1,670 1,540 1,510 450 450 450 450 450 11,380 11,750 5,180 9,230 7,810 1,810 1,540 1,680 1,610 1,690 5,740 4,870 6,230 4,510 5,060 1,290 1,040 1,330 1,040 1,040 220 220 220 220 220 9,060 7,670 9,460 7,380 8,010 21320 4,080 -4,280 1,850 -200 1998 1990 2C 2001 2002 14,110 21,850 15,290 28,400 24,750 1,590 1,480 1,590 1,460 1,510 5,070 4,500 4,540 4,240 4,320 8,190 15,730 9,330 22,100 8,680 4,530 4,610 4,340 5,390 4,950 6,340 6,300 6,740 6,250 6,280 39,830 54,470 41,830 67,840 50,490 13,640 16,240 14,520 16,330 16,290 2,630 2,430 3,190 1,590 2,090 4,150 3,680 3,720 3,470 3,550 810 720 800 640 700 4,530 4,610 4,340 5,390 4,950 390 4,490 620 6,300 4,680 780 760 810 740 760 930 810 820 770 780 1,330 1,370 1,520 1,940 760 10,660 19,360 11,520 30,660 15,950 39,850 54,470 41,860 67,830 50,510 390 4,490 620 6,300 4,680 780 760 810 740 760 930 810 820 770 780 1,330 1,370 1,520 1,940 760 450 450 450 450 450 3,880 7,880 4,220 10,200 7,430 1,590 1,480 1,590 1,460 1,510 5,070 4,500 4,540 4,240 4,320 1,140 1,040 1,140 950 1,050 220 220 220 220 220 8,020 7,240 7,490 6,870 7,100 -4,140 640 -3,270 3,330 330 2004 2005 201 2007 8,150 14,650 11,060 22,500 31,800 1,790 1,730 1,510 1,400 1,370 5,340 5,300 5,090 4,520 4,590 8,300 14,780 10,410 30,350 29,200 4,200 4,010 3,930 4,160 4,480 6,840 6,730 6,580 5,860 5,530 34,620 47,200 38,580 68,790 76,970 8,130 14,120 10,940 16,240 16,300 3,540 3,550 3,390 2,400 1,750 4,380 4,350 4,190 3,730 3,780 880 830 830 690 650 4,200 4,010 3,930 4,160 4,480 0 430 90 4,850 7,160 910 910 790 720 700 950 950 900 790 810 1,340 2,390 1,680 2,650 1,740 10,260 15,640 11,830 32,560 39,610 34,590 47,180 38,570 68,790 76,980 0 430 90 4,850 7,160 910 910 790 720 700 950 950 900 790 810 1,340 2,390 1,680 2,650 1,740 450 450 450 450 450 3,650 5,130 3,910 9,460 10,860 1,790 1,730 1,510 1,400 1,370 5,340 5,300 5,090 4,520 4,590 1,250 1,260 1,140 960 1,150 220 220 220 220 220 8,600 8,510 7,960 7,100 7,330 -4,950 -3,380 -4,050 2,360 3,530 200- 2009 2010 2011 2012 15,910 9,930 9,810 11,190 19,070 1,470 1,550 1,500 1,280 1,190 4,980 5,570 5,140 5,910 4,890 7,240 4,930 4,390 2,110 6,410 3,950 4,060 3,660 3,420 3,550 5,770 6,330 6,190 5,750 5,490 39,320 32,370 30,690 29,660 40,600 14,770 9,860 9,740 11,060 16,040 2,560 3,060 3,300 2,950 2,500 4,100 4,570 4,220 4,860 4,040 810 450 440 430 770 3,950 4,060 3,660 3,420 3,550 880 70 50 110 2,330 740 780 750 670 650 880 1,000 920 1,050 860 1,170 800 720 340 1,040 9,430 7,740 6,890 4,750 8,810 39,290 32,390 30,690 29,640 40,590 880 70 50 110 2,330 740 780 750 670 650 880 11000 920 1,050 860 1,170 800 720 340 11040 450 450 450 450 450 4,120 3,100 2,890 2,620 5,330 1,470 1,550 1,500 1,280 1,190 4,980 5,570 5,140 5,910 4,890 1,200 1,350 1,290 1,270 1,170 220 220 220 220 220 7,870 8,690 8,150 8,680 7,470 -3,750 -5,590 -5,260 -6,060 -2,140 2013 2014 2015 2016 2017 31,800 13,110 28,250 1,250 1,280 1,170 5,190 4,740 4,380 24,690 3,280 21,840 4,400 3,330 4,360 5,370 5,790 5,080 72,700 31,530 65,080 16,300 12,890 16,430 1,600 3,080 1,300 4,280 3,930 3,630 630 840 670 4,400 3,330 4,360 12,640 180 8,800 660 690 630 910 820 750 1,420 270 1,260 29,860 5,510 27,270 72,700 31,540 65,100 12,640 180 8,800 660 690 630 910 820 750 1,420 270 1,260 450 450 450 16,080 2,410 11,890 1,250 1,280 1,170 5,190 4,740 4,380 1,260 1,270 1,070 220 220 220 7,920 7,510 6,840 8,160 -5,100 5,050 2018 2019 Type Year: Dry / / / Wet AF = Acre -Feet; KEY = Referenced Components on Figure 6-3 10 Page 247 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 60000 40000 20000 4r m V !6 tll ;= 0 3 O l6 7 -20000 a -40000 -60000 -80000 Water Budget (§ 354.18) Surface Water Budget - San Luis Valley Subarea I--' N N N N N N N N N N N N N N N N N N N N lD lD lD lD lD lD lD lD lD lD lD lD lD 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 co co co cD cD cD cD cD cD cD cD cD cD 0 0 0 0 0 0 0 0 0 0 N N N N V co Lo 0 N ry w A cr rn v 00 cD o N n) w A c,+ rn V oQ cn 0 N ry w A Ln rn V co cD Water Year ■ Precipitation (+) ■ Wastewater Discharge+) ■ Infiltration of Precipitation-) ■ GW-SW Interaction (-) ■ Groundwater Extraction+) ■ Imported Supplies (+) ■ Applied Water Inflitration -) ■ Surface Water Deliveries Offset(-) ■ Stream Inflow (+) ■ Evapotranspiration-) ■ Stream outflow (-) Figure 6-4: Surface Water Budget — San Luis Valley Subarea. 11 Page 248 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 40000 30000 ►AIIIIIII] <D 10000 m m d 0 0 7 -10000 Q I M8181lI11 -30000 Surface Water Budget - Edna Valley Subarea I— I" I" I" I" I" I" I" I" I" I" I" I-.. N N N N N N N N N N N N N N N N N N N N to to to to to to to to to to to to to 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 00 00 cn [,0 [,0 [0 [o [o [o cn [o [0 0 0 0 0 0 0 0 0 0 0 N N N N N N N N N N 1l 00 L0 0 N W A [r m -,l 00 cn 0 N N W A [s+ 0� -1 00 L0 0 W A [s+ rn J 00 L0 Water Year ■ Precipitation+) ■ Groundwater Extraction+) ■ Stream Inflow (+) ■ GW-SW Interaction-) ■ Evapotranspiration-) ■ Infiltration of Precipitation-) r Applied Water Inflitration-) ■ Stream Outflow (-) Figure 6-5: Surface Water Budget — Edna Valley Subarea. 12 Page 249 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 100000 80000 60000 40000 += m m 20000 V [6 d) 0 0 -20000 a -40000 -60000 -80000 -100000 Surface Water Budget - Basin Total lD lD lD lD lD lD lD lD lD lD lD lD lD O O O O O O Cl Cl Cl Cl Cl Cl Cl Cl O O O O O O CO CO CO W W W W W W W W W W O O O O O O O O O O F- F- I--' I -A V CO lD O I" N W A Ir M V CO lD O I" N W A Ir M V CO lD O I" N W A Ir M V CO lD Water Year ■ Precipitation+) ■ Groundwater Extraction ■ Stream Inflow+) ■ Wastewater Discharge+) ■ Imported Supplies (+) ■ Evapotranspiration-) ■ Infiltration of Precipitation-) ■ Applied Water Inflitration-) ■ Stream Outflow-) ■ GW-SW Interaction (-) ■ Surface Water Deliveries Offset(-) Figure 6-6: Surface Water Budget — Basin Total. 13 Page 250 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO m m m 10000 8000 111 4000 2000 W E j 0 m c c a -2000 -4000 -6000 '111 Water Budget (§ 354.18) Groundwater Budget - San Luis Valley Subarea N N N N N N N N N N N N N N N N N N N N lD lD lD lD W W W lD lD lD lD lD lD 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m m m lD lD W W lD lD lD W W W 0 0 0 0 0 0 0 0 0 0 r r r r r r r r j CO W 0 F_- N W In M -4 CO W 0 F_- N W A UJ� W lD 0 F_- N W 4!�- LJ 6') J W c0 Water Year ■ Infiltration of Precipitation+) ■ Infiltration of Applied Water+) ■ GW-SW Interaction+) ■ Subsurface Inflow+) ■ Groundwater Extraction-) Subsurface Outflow(-) ■ Wetland direct ET Figure 6-7: Groundwater Budget — San Luis Valley Subarea. 14 Page 251 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Oiii loll 111111mi NMI 111111I 11111111111111111 1111111 �iinii ii 1111ml 15 Page 252 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 15000 10000 -5000 -10000 Water Budget (§ 354.18) Groundwater Budget - Basin Total 11111iiiin 11111mil IM1111 111111 Ili Rim ini irii mill ni immni 1111 innni -I i inmmmi ii imi I Hi 111111111111111111111111111111111111111111111111111111111111111 i����ddnnnndn�nddnn��dddnnddddnnn� F-' F-' F-' I -A I--' N N N N N N N N N N N N N N N N N N N N lD lD lD lD lD lD lD �D kD kD kD kD kD a a a a a o o a o o a a a a a o 0 o a a co co co W W W W cD cD cD cD cD cD 0 0 0 0 0 0 0 0 0 0 r N N N N N N N N N I! W kD (D 6) _1 W [D O N W A cn 61 _1 CO Q0 CD 61 _1 CO [D Water Year ■ Infiltration of Precipitation+) ■ Infiltration of Applied Water+) ■ Subsurface Inflow [+] ■ GW-SW Interaction+) ■ Groundwater Extraction-) Subsurface Outflow(-) ■ Wetland direct ET (-) Figure 6-9: Groundwater Budget — Basin Total. 16 Page 253 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Climate is one of the principal measures of water supply conditions and is used for hydrologic base period definition and for developing evapotranspiration estimates. The main component of climate monitoring in the Basin is rainfall, with records at the Cal Poly NOAA Station (formerly Cal Poly #1) beginning in the 1870- 71 rainfall year. Rainfall is used in the water budget for establishing the hydrologic base period needed for representing long-term water supply conditions. Another climate parameter used in the water budget is evapotranspiration. Evapotranspiration is calculated from a combination of monitored parameters, such as air temperature, wind speed, solar radiation, vapor pressure, and relative humidity. These parameters, along with precipitation, have been monitored at CIMIS Station #52 (San Luis Obispo — Cal Poly) since 1986. The water budget uses crop evapotranspiration for estimating the applied irrigation requirements for crops (see Section 6.3.4.2). Cal Poly, the San Luis Valle, and the Edna Valley are all within DWR reference evapotranspiration Zone 6, which is one of 18 climate zones in California based on long-term monthly average reference evapotranspiration (CIMIS, 1999). 6.1.1 Historical Climate/Base Period The historical rainfall record at the Cal Poly NOAA Station has been used to define a period of years, referred to as a base period, which represents long-term hydrologic conditions. As described by DWR (2002): The base period should be representative of long-term hydrologic conditions, encompassing dry, wet, and average years of precipitation. It must be contained in the historical record and should include recent cultural conditions to assist in determining projected Basin operations. To minimize the amount of water in transit in the zone of aeration, the beginning and end of the base period should be preceded by comparatively similar rainfall quantities. The historical rainfall record for the Cal Poly NOAA Station, which is the longest record in the San Luis Obispo area, was presented in Figure 3-11; Chapter 3. The water year in San Luis Obispo County for rainfall runs from July 1 through June 30 (also referred to as rainfall year), while other hydrologic data is reported from October 1 through September 30 (San Luis Obispo County, 2005). These conventions are maintained for the water budget, and water years are referenced herein based on the ending year. The hydrologic base period selected to represent historical climatic conditions for the Basin encompasses the years 1987 through 2019 (33 years). Average precipitation at the Cal Poly NOAA gage over this base period was 21.76 inches, compared to the long-term average of 21.95 inches, and included wet, average, and dry periods (Figure 6-10). These periods are visually defined by the movement of the cumulative departure from mean precipitation curve, which declines over dry periods, is flat through average periods, and rises over wet periods. 17 Page 254 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 60 50 .. 40 c m M Cr 30 3 C Q 20 10 0 1985 1995 2005 2015 Water Budget (§ 354.18) Historical Precipitation - Cal Poly Rain Gage Rainfall (in) Overall Average Rainfall Cumulative Departure From Mean Rainfall Type of Rainfall Year: 0 Dry 0 Below Normal 0 Above Normal 0 Wet Water Year Figure 6-10: 1987-2019 Historical Base Period Climate. 18 150 m 3 c c Q M v 50 15 E 0 4- G1 L 3 t M Q 0 N a+ f6 7 E 7 U -50 -100 Page 255 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Water year types for this water budget have been developed and classified based on annual precipitation as a percentage of the previous 30-year average precipitation. Each July 1 through June 30 rainfall year of the historical base period was given a ranking of 1 (wettest) through 30 (driest) based on a comparison to a 30-year (rolling) data set. The minimum precipitation threshold for wet type years was assigned based on the average for the 10th ranked year (26.3 inches). The maximum precipitation threshold for dry type years was assigned based on the average for the 21st ranked year (16.8 inches). Below normal (from 16.8 to less than 20.5 inches) represents the 16th through 20th ranked years, while above normal (from 20.5 to 26.3 inches) represents the 10th through 15th ranked years. Note that the division between below normal and above normal rainfall (20.5 inches) is less than the average over the base period (21.76 inches) because there are more below average rainfall years than above average years. The water year types were developed from Cal Poly NOAA rainfall records, with one exception. The exception is the 2006 rainfall year, which would be classified as dry based on 15.31 inches reported at Cal Poly NOAA, but which is considered above normal when reviewing other local rain gages, including the Gas Company rain gage (23.35 inches in 2006). The base period includes recent cultural conditions, such as expanded recycled water use by the City and water conservation by Basin users in response to the recent drought period. Differences between water in transit in the vadose zone (deep percolation of precipitation and stream seepage) are minimal, based on comparing the two rainfall years leading up to the beginning and ending of the base period. The 1985 and 1986 rainfall years leading in the base period have 14.77 inches and 29.43 inches, respectively, compared to 14.34 and 29.48 inches of rainfall at the end of the base period in 2018 and 2019 (Figure 6-10). There are other rainfall gages in the Basin (Table 3-5 and Figure 3-10; Chapter 3), and an isohyetal map of average annual rainfall is shown in Figure 4-3 (Chapter 4). The average annual precipitation across the Basin between 1981 and 2010 was approximately 19 inches (Figure 4-3; Chapter 4), compared to the Cal Poly NOAA rainfall gage, which averaged 23.03 inches over that same period. Although the water budget uses the Cal Poly NOAA gage (formerly Cal Poly #1) to identify the historical base period and water year types due to the extensive period of record, the Gas Company rain gage is used in water budget calculations that involve precipitation volumes to account for the difference between rainfall at Cal Poly and the Basin. A correlation between the Gas Company and Cal Poly NOAA was performed to estimate rainfall prior to 2006 for the historical water budget (Figure 6-11). Based on linear regression using data recorded between 2006 and 2019, rainfall at the Gas Company gage is approximately 90 percent of rainfall at the Cal Poly NOAA gage. No precipitation data was recorded for the Gas Company rain gage prior to 2006, and the 90 percent correlation was used to estimate precipitation at the gage between 1987 and 2005 to complete the historical base period. Climate data from CIMIS Station #52 (located within same enclosure as the Cal Poly NOAA rain gage) has been used for evapotranspiration and applied agricultural water estimates. 19 Page 256 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 40 35 m 25 a E 0 v 20 w 15 ca 5 a Water Budget (§ 354.18) Rainfall Correlation 2006-2019 Cal Poly NOAA vs. Gas Company y = 0.902x R2 = 0.9625 ♦ ♦ 0 5 10 15 20 25 30 35 40 Annual Rainfall at Cal Poly NOAA (inches) ♦ Water Year data Linear (Water Year data) Figure 6-11: Rainfall Correlation Cal Poly vs. Gas Company. 20 Page 257 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Water Budget (§ 354.18) Table 6-4 presents the annual rainfall for the historical water budget. Average annual rainfall within the Basin over the historical base period is estimated to be 19.6 inches. This average closely matches the estimated value for average rainfall across the Basin on the 30-year isohyetal map (Figure 4-3; Chapter 4). Table 6-4: Historical Base Period Rainfall. Year Type Cal Poly NOAA Gas Company Rainfall (in.) 1987 Dry 15.19 13.67 1988 Below Normal 19.85 17.87 1989 Dry 15.46 13.91 1990 Dry 13.36 12.02 1991 Below Normal 18.6 16.74 1992 Above Normal 22.14 19.93 1993 Wet 30.9 27.81 1994 Below Normal 16.96 15.26 1995 Wet 44.31 39.88 1996 Above Normal 23.11 20.8 1997 Wet 31.36 28.22 1998 Wet 43.98 39.58 1999 Below Normal 17.07 15.36 2000 Above Normal 24.84 22.36 2001 Above Normal 24.54 22.09 2002 Dry 14.79 13.31 2003 Above Normal 22.9 20.61 2004 Dry 16.02 14.42 2005 Wet 29.76 26.78 2006 Above Normal* 15.31 23.35 2007 Dry 11.03 7.68 2008 Below Normal 19.88 13.82 2009 Dry 10.35 10.43 2010 Wet 31.73 21.22 2011 Wet 31.5 32.4 2012 Dry 14.62 15 2013 Dry 14.33 9.37 2014 Dry 10.61 9.25 2015 Dry 11.52 10.55 2016 Below Normal 19.47 17.99 2017 Wet 38.93 37.23 2018 Dry 14.34 12.37 2019 Wet 29.48 26.65 Average 21.8 19.6 Gas Company Estimates in blue (approximately 90% of Cal Poly) *2006 type year based on Gas Company gage reporting 21 Page 258 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 6.2 WATER BUDGET DATA SOURCES The following sources and types of data have been used for the water budget: • Hydrogeologic and geologic studies and maps • Groundwater monitoring reports • County stream flow gages • County and NOAA precipitation Stations • PRISM 30-year normal dataset (1981-2010) • CIMIS weather station data • Aerial Imagery • County water level monitoring program • San Luis Obispo City, County and DWR land use data and planning documentation • County Ag commissioner's office data sets • County Water Master Plan • Geotracker Groundwater Information System • Stakeholder supplied information • Environmental Impact Reports • Water rights filings • SRWQCB Drinking Water Division Water systems • Wastewater discharge reports 6.3 HISTORICAL WATER BUDGET In accordance with GSP regulations, the historical water budget shall quantify the following, either through direct measurement or estimates based on data (reference to location of data in Chapter 6 also listed): (1) Total surface water entering and leaving a Basin by water source type (Table 6-3). (2) Inflow to the groundwater system by water source type, including subsurface groundwater inflow and infiltration of precipitation, applied water, and surface water systems, such as lakes, streams, rivers, canals, springs, and conveyance systems (Table 6-3). (3) Outflows from the groundwater system by water use sector, including evapotranspiration, groundwater extraction, groundwater discharge to surface water sources, and subsurface groundwater outflow (Table 6-3). (4) The change in annual volume of groundwater in storage between seasonal high conditions (Table 6-3). (5) If overdraft occurs, as defined in Bulletin 118, the water budget shall include a quantification of overdraft over a period of years during which water year and water supply conditions approximate average conditions (Section 6.3.8). (6) The water year type associated with the annual supply, demand, and change in groundwater stored (Table 6-3). (7) An estimate of sustainable yield for the Basin (Section 6.3.7). 6.3.1 Historical Time Period The time period over which the historical water budget is estimated is the hydrologic base period from 1987-2019 (33 years). Groundwater storage calculations using the specific yield method were performed for 1986, 1990, 1995, 1998, 2005, 2011, 2014, and 2019. These years include the beginning and ending years in the base period, along with sufficient intervening years to characterize change in storage trends through the base period. 22 Page 259 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 6.3.2 Historical Land Use Land use is one of the primary data sets used in developing a water budget. Several types of land use/land cover in the basin have been used to estimate components of the water budget. For example, the acreages of various crops are multiplied by their respective water use factors to estimate agricultural groundwater extractions (Section 6.3.4.2), and acreages of various land covers are multiplied by empirical correlations to estimate their respective evapotranspiration and percolation of precipitation (Section 6.3.4.1). The land uses/land covers including the following: • Irrigated Agriculture o Citrus o Deciduous o Pasture o Vegetable o Vineyard • Native Vegetation o Brush, trees, native grasses o Wetlands/open water • Urban/Suburban o Developed (City, subdivisions) o Open space (parks, empty lots) o Turf (golf courses, play fields) Irrigated Agriculture Irrigated crop acreage was estimated from aerial imagery of the Basin for the following years: 1987, 1994, 1999, 2003, 2005, 2007, 2009, 2010, and 2011. San Luis Obispo County land use data was used for crop acreage from 2013 to 2018. DWR land use surveys for 1985, 1995, and 2014 were also reviewed during the interpretation of aerial imagery. Figure 6-12 shows an example of the County irrigated crop data set for 2016. 23 Page 260 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Prepared For: N References: Notes: San Luis Obispo Valley Basin Irrigted Crops 1. Projection State n State Plane Conic mla V HIPS O405 Feet 1- 2U16 Au[hor_ TK 2. Projectlo n'. Lambert Conformal Conic 2. g 0 025 0.5 0.75 1 mi Date: 05/21 /2020 3. Hirozo vital Datum: NAD 83 3. 4. Vertical Datum: NAVD 88 0 0.5 1 km 5. Baseman:: 2016 NAIP Satellite Imagery SAN LUIS OBISPO VALLEY BASIN GSP Figure 6-12 24 Page 261 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Irrigated acreage for years in the historical base period without aerial imagery, surveys, or County data were estimated from the nearest available year with data. Acreages for irrigated crops, estimated from aerial imagery and County datasets within the historical base period are shown in Table 6-5. Table 6-5: Irrigated Agriculture Acreages. 1987 1994 1999 2003 12005 2007 2009 12010 2011 2013 2014 2015 12016 2017 2018 Crop Type San Luis Valley Subarea (acres) Citrus 26 26 30 51 49 49 49 49 49 45 44 44 44 46 46 Deciduous 12 12 12 12 12 12 12 12 12 67 21 17 17 17 17 Pasture 33 22 27 28 28 28 28 28 28 28 37 37 53 28 28 Vegetable 594 766 880 647 592 487 526 494 495 488 490 532 593 492 363 Vineyard 0 5 6 6 8 58 58 58 58 92 86 86 86 86 86 Subtotal 665 831 955 744 689 634 673 641 642 720 678 716 793 669 540 Edna Valley Subarea (acres) Citrus 12 6 47 49 51 51 53 49 105 105 111 111 191 191 210 Deciduous 0 0 0 0 0 0 0 0 0 0 2 2 2 4 3 Pasture 138 19 19 19 19 19 19 19 19 16 19 19 15 14 13 Vegetable 533 703 685 686 646 699 663 679 647 671 670 691 394 505 453 Vineyard 1,180 1,344 1,900 2,252 2,297 2,377 2,377 2,372 2,380 2,423 2,419 2,419 2,454 2,415 2,323 Subtotal 1,863 2,072 2,651 3,006 3,013 3,146 3,112 3,119 3,151 3,215 3,221 3,242 3,056 3,129 3,002 Native Vegetation and Urban Areas Native vegetation acreages were compiled using data sets from the National Land Cover Database (NLCD), which is derived primarily from satellite imagery. The years for which NLCD coverage is available are 2001, 2004, 2006, 2008, 2011, 2013, and 2016. Adjustments to the acreages in the NLCD data were performed to reconcile with the agricultural acreages and urban turf areas (golf course, play fields) compiled using the aerial imagery and crop survey data set. Where the NLCD data sets showed less agricultural acreage than the aerial imagery, the native vegetation (brush, trees, grassland) acreage was reduced so the total basin acreage remained constant. The estimated acreages for native vegetation and urban areas, along with irrigated agriculture interpolated from Table 6-5, are presented in Table 6-6 below. 25 Page 262 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Table 6-6: Land Cover Acreages. Water Budget (§ 354.18) Land cover 2001 2004 2006 1 2008 2011 2013 2016 San Luis Valley Subarea (acres) Native - brush, trees, grassland 2,315 2,450 2,482 2,466 2,386 2,315 2,203 Native - wetlands/open water 566 566 573 571 569 569 575 Urban - Developed 2,150 2,142 2,219 2,219 2,325 2,312 2,353 Urban - Open Space 870 875 841 841 829 835 825 Urban -Turf 23 23 23 23 23 23 23 Irrigated Agriculture 849 716 636 653 642 720 793 Subarea Total 6,773 6,773 6,773 6,773 6,773 6,773 6,773 Edna Valley Subarea (acres) Native - brush, trees, grassland 2,659 2,473 2,406 2,356 2,333 2,266 2,423 Native - wetlands/open water 13 17 13 13 15 13 13 Urban -Developed 230 230 232 232 232 235 237 Urban - Open Space 77 77 77 77 77 78 79 Urban -Turf 141 141 141 141 141 141 141 Irrigated Agriculture 2,829 3,010 3,079 3,129 3,150 3,215 3,056 Subarea Total 5,948 5,948 5,948 5,948 5,948 5,948 5,948 6.3.3 Historical Surface Water Budget The surface water system is represented by water at the land surface within the boundaries of the Basin. Surface water systems for the water budget include streams and Laguna Lake. 6.3.3.1 Components of Surface Water Inflow The surface water budget includes the following sources of inflow: • Local Supplies o Precipitation o Groundwater extractions o Stream inflow at Basin boundary o Groundwater -Surface Water Interactions o Treated wastewater discharge into streams • Local Imported Supplies o Nacimiento Project Water o Salinas Reservoir Water o Whale Rock Reservoir Water Precipitation Precipitation occurs as rainfall. The annual volume of rainfall within the Basin has been estimated by multiplying the rainfall year totals in Table 6-4 by each Basin subarea. Rainfall volumes falling within the Basin boundary are shown as precipitation in the surface water inflow budget of Table 6-1, Table 6-2, and Table 6-3. Groundwater Extractions Groundwater extractions are included in the surface water budget as inflow because after extraction groundwater is distributed and applied at land surface. The surface water budget includes the land surface 26 Page 263 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO system and rivers & streams system (Figure 6-2). These extractions are the divided into Urban and Agricultural water use sectors and match the groundwater extraction outflow values from the groundwater budget. Details on data collection and groundwater pumping estimates are provided in the Historical Groundwater Budget section (Section 6.3.3). Stream Inflow at Basin Boundary Inflow along stream channels at the Basin boundary has been estimated based on paired watershed methodology. The total watershed area drained by the Basin was divided into 15 sub -watershed areas, one of which was the subarea drained by San Luis Obispo Creek upstream of the Andrews Street gage (sub - watershed 1, Figure 6-13). Flow from 2007 through 2018 at the Andrews Street gage was reconstructed using stage records and a stage -discharge curve. The resulting annual flows were then processed using a watershed area factor and an isohyetal factor to estimate annual flows for each of the other 14 subareas. The watershed area factor was the ratio of the watershed area for which flow was being estimated to the Andrews Street gage watershed area. The isohyetal factor addressed differences between the average annual rainfall across each of the sub -watersheds being compared (Figure 6-13), and consisted of the ratio of average annual precipitation over 15 inches between sub -watersheds. Correlation between rainfall and runoff for the paired watersheds are shown in Figure 6-14. A drought period adjustment was also made for 1989-1991 inflow estimates (Figure 6-14) consisting of 3,000 AFY less inflow for the San Luis Valley subarea and 1,000 AFY less inflow for the Edna Valley subarea. Once these factors were applied, the estimated stream flow entering the respective SLO subarea watershed and Edna Valley subarea watershed were totaled. 27 Page 264 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Explanation 31 { a .. 1. ' t_.. � <J I-� ,� � �3UP r J SLO Valley Groundwater _ Basin Boundary `tip Subarea Boundary All Line of Equal Precipitation lip_ ~ : ' r �, in inches (2-inch interval) ,y ----- Creek = Watershed Boundary E3 Pismo Creek San Luis Obispo Creek Andrews St: Bridge Gage I IF J l �)j■/ r ^f ,I "' (,� `� vim' ,� �I 'y . f —... �' e.�, _ 1. � -;-s, .-- 1+�.' — �J- f• f ��' �' �`/ �,_.. •,`: 41 jv 1� All ''. � __ _ .; ,`� ' r✓ I � � - . ###«err �� , s � +�'�'_,t M,, Lys.`-*'m , . _ `�� zo', ;', f • r '0 � _ V- Cam`; ram. ,;. ♦� - ' i Prepared For: N References: _ 1 Coordinate System onf Plane onic mia VFIPS 0405 Feet Author TK n 2. Projection_ Lambert Conformal Conic - Date O6/16/2020 ,/■,\`\\V 0 0 5 1 7.5 rti 3. Hirozor�tal Datum' PAD 83 � 4. Vertical Datum_ NAVD 88 0 0.5 1 1.5 2km 5. Baseman. USGS75'Topographic Map SAN LOIS OBISPO VALLEY BASIN GSP 0001=31I Notes: 1_ Precipitationdata fiom. PRISM 30 yr Normal dataset(1981-2010) 2 3. Basin Sub -watershed Areas and Isohyetals Figure 6-13 28 Page 265 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 30000 25000 .. 20000 a `u m w0 15000 c 3 f0 7 C a 10000 5000 a Runoff vs Rainfall 2007-2019 y = 729. 8x - 4367 7 RZ 0.7979 e� at° �.� y = 258.37x 1546.1 Rz = 0.7 79 0 5 10 15 20 25 30 Annual rainfall (inches) SLO Subarea ■ Edna Subarea Linear (SLO Subarea) 35 40 45 Linear (Edna Subarea) Figure 6-14: Runoff vs Rainfall Correlation for Subareas. 29 Page 266 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Stream inflow on the West Coral de Piedra sub -watershed 5 (Figure 6-13) was reduced to account for surface water diversions. There is a permitted reservoir where surface water diversion is utilized mainly for agricultural irrigation (SWRCB, 1990). The stream inflow adjustment consisted of correlating the total reported diversions from Statements of Diversion and Use between 2010 and 2018 with annual precipitation, and applying the correlation to other years in the base period (the r-squared value of the correlation 0.71) is. Reported annual surface water diversions ranged from 14 acre-feet to 900 acre-feet, with average annual diversion over the base period estimated at 350 acre-feet per year (AFY), including estimated reservoir evaporation which was added to the diversion. The resulting estimated stream inflow estimates for the historical base period are shown in the surface water budget of Table 6-1, Table 6-2, and Table 6-3. Groundwater -Surface Water Interaction (Net) Groundwater -surface water interactions take place primarily along stream channels. When groundwater is rising into streams (gaining reaches of a stream), the interaction is a surface water budget inflow and a groundwater budget outflow. Conversely, when stream flow is percolating to groundwater (losing reaches of a stream), the interaction is a surface water budget outflow and groundwater budget inflow. This water budget has combined the gaining and losing stream reaches into single (net) term, the result of which are net losing streams in the Basin which is an outflow component of the surface water budget and inflow component of the groundwater budget. Net groundwater -surface water interaction was estimated by adjusting the percent of stream inflow that recharges groundwater while optimizing the water balance. The optimization consisted of minimizing the sum of squares of the residual error between the calculated change in storage and measured change in storage (Section 6.3.4.1). Treated wastewater discharge to streams The City of San Luis Obispo discharges treated wastewater into San Luis Obispo Creek. Available records of wastewater treatment plant discharges have been compiled by water year. Daily discharge records provided by the City were compiled for water years 2001-2019. For water years 1987-2000, treated wastewater discharges were estimated as a nominal 65 percent of total City water deliveries, based on the average ratio of annual wastewater flows to water deliveries in the years 2001-2019. The treated wastewater discharges to San Luis Obispo creek are presented in the surface water budget of Table 6-1. Local Imported Supplies The City of San Luis Obispo imports water from three reservoirs. Surface water deliveries from Salinas and Whale Rock reservoirs occurred through the historical base period, while Nacimiento reservoir water deliveries to the City began in 2011. Surface water reservoirs have historically provided most of the water supply used by the City. Local imported water supplies are based on City records and Boyle (1991). Local imported supplies are presented in the surface water budget of Table 6-1. Cal Poly imports surface water and also pumps groundwater for agricultural irrigation. Fields overlying and adjacent to the Basin are typically irrigated with groundwater, while imported surface water is generally used for irrigation outside of the Basin boundary. Therefore, only the local imported supplies used for potable water deliveries by the City have been accounted for in the GSP water budgets. 6.3.3.2 Components of Surface Water Outflow The surface water budget includes the following sources of outflow: • Evapotranspiration of Precipitation • Evapotranspiration of Applied Water • Infiltration of Precipitation • Infiltration of Applied Water 30 Page 267 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO • Surface Water Deliveries Offset • Wetland/Lake ET • Groundwater -Surface Water Interaction • Stream outflow (runoff) Evapotranspiration of Precipitation The fate of precipitation that falls within the Basin boundaries can be divided into three components: evapotranspiration, infiltration, and runoff. Of these three, infiltration has the greatest influence on the groundwater budget and ultimately, Basin sustainable yield. Therefore, the approach to estimating the fate of precipitation uses a methodology focused primarily on infiltration, but from which the other two components may also be estimated. This methodology is based on work by Blaney (1933, 1963), and which has been used for other analytical water budgets in major studies of central coast Basins (DWR, 2002; Fugro, 2002). Evapotranspiration is the evaporation of water from surfaces and the transpiration of water from plants. The first seasonal rains falling on the Basin are mostly evaporated directly from surfaces (vegetative canopy, soil, urban area hardscapes) and used to replenish soil moisture deficits that accumulate during the dry season. For the Arroyo Grande — Nipomo Mesa area of the Santa Maria groundwater Basin, DWR (2002) assumed that precipitation could begin to infiltrate to groundwater (deep percolate) only after 11 inches of annual precipitation had fallen in urban and agricultural irrigation areas, and when 17 inches of rainfall had fallen in areas of native vegetation. In the Paso Robles groundwater Basin, an estimated 12 inches of annual rainfall was needed for infiltration below agricultural lands, while 18 inches of rainfall was needed for infiltration beneath native ground cover and urban/suburban areas (Fugro, 2002). These threshold values for minimum annual rainfall prior to infiltration are assumed to approximate the annual evapotranspiration of precipitation. Once these thresholds are exceeded, infiltration to groundwater and runoff would become dominant. It is recognized that a portion of the initial annual rainfall may result in runoff, depending on rain intensity, but this is assumed to be offset by the portion of the late season rainfall that is evapotranspired. Since infiltration is the critical component of precipitation with respect to Basin safe yield, offsetting of early wet season runoff with late wet season evapotranspiration in the water budget is considered a reasonable approach. The specific thresholds for annual rainfall that is estimated to evapotranspire prior to infiltration and runoff have been developed from Blaney's field studies. Evapotranspiration of precipitation has been estimated by multiplying land use/land cover acreages by the infiltration threshold values. Results of these estimates are shown in the surface water budget of Table 6-1, Table 6-2, and Table 6-3. Additional details of the methodology are provided in section 6.3.4.1 (Components of Groundwater Inflow). Evapotranspiration of Applied Water The evapotranspiration of applied irrigation water has been divided into urban and agricultural sectors. Urban applied water includes residential outdoor irrigation, urban recycled water use, and golf course/play field irrigation. Much of the urban applied water is accounted for by City of San Luis Obispo or other water purveyor records. Estimation of applied water for urban and agricultural irrigation not supplied by purveyors involves a soil -moisture balance approach discussed in section 6.3.4.1 (Components of Groundwater Outflow). Most water applied for irrigation is taken up by plants and transpired. Some water, however, is lost to evaporation or infiltrates to groundwater as return flow. The evapotranspiration of applied irrigation water has been calculated by subtracting the estimated return flow from the applied water estimates. Both 31 Page 268 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO applied water and return flow estimates are presented under the historical groundwater budget section. Results of the calculations of evapotranspiration of applied water are shown in the surface water budget of Table 6-1, Table 6-2, and Table 6-3. Riparian Corridor Evapotranspiration Riparian plant communities present along the creeks can access surface flows and creek underflow. Riparian areas are included within the native brush, trees, and grasses acreage for the subareas (Table 6-6). Besides evapotranspiration of precipitation, however, an additional 0.8 acre-feet per acre of consumptive water use is estimated for riparian corridors (Fugro, 2002; Robinson, 1958) that lie within potential Groundwater Dependent Ecosystems, which cover approximately 200 acres in the San Luis Valley subarea and 50 acres in the Edna Valley Subarea (Figure 5-15; Chapter 5). Riparian corridor water use during severe drought is reduced a nominal 50 percent to reflect lack of creek underflow. Riparian evapotranspiration is included in Table 6-1, Table 6-2, and Table 6-3. Infiltration of Precipitation and Applied Water Infiltration of precipitation and applied water are both outflow components from the surface water budget and inflow components to the groundwater budget. Discussion of these components is provided in Section 6.3.4.1 (Components of Groundwater Inflow). Surface Water Deliveries Offset When imported surface water is brought into the Basin from local supplies (Salinas Reservoir, Whale Rock Reservoir, and Nacimiento Reservoir), it is counted as surface water inflow. This imported water is then provided to customers through surface water deliveries from the City water treatment plant. After residential and business use, most of the delivered water is conveyed by sewer to the wastewater treatment plant for recycling and discharge into San Luis Obispo Creek. Since wastewater discharges to the creek are also counted as surface water inflow, an offset factor is needed to avoid double counting that portion of imported surface water. The surface water deliveries offset is an outflow equal to the wastewater discharges inflow and is shown in the surface water budget of Table 6-1. Laguna Lake Laguna Lake is an approximate 100-acre open water body within the San Luis Valley subarea (Figure 3-10; Chapter 3). There are an additional 100 acres of adjacent wetlands connected to the lake. Evaporation from the water surface and transpiration by phreatophytes in the wetlands are included in the water budget as surface water outflow. Local pan evaporation is estimated at 70 inches per year (for all years), with a reservoir coefficient of 0.7, based on a review of information from nearby reservoirs (San Luis Obispo County, 2005). The resulting estimated annual evaporation rate for this water budget component is 4.1 feet (not including offset from direct precipitation). Evapotranspiration by phreatophytes were estimated to use lake water at a rate equal to irrigated pasture applied water demand. Results for Wetland/Lake ET outflow from the surface water budget are shown in Table 6-1. As with riparian water use, during severe drought the lake and wetland evapotranspiration is reduced by 50 percent. Groundwater -Surface Water Interaction (Net) Groundwater -surface water interaction involves both surface water and groundwater budgets. The net interaction is an outflow component for the surface water budget and an inflow component for the groundwater budget (losing streams. Details of the methodology used to develop the groundwater -surface water interaction are presented in the Sections 6.3.4.1 and 6.3.6. Stream Outflowfrom Basin 32 Page 269 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Stream outflow from each subarea was estimated using the water balance method and compared to available flow records. No significant changes to surface water in storage are assumed in the water budget from year to year. Storm water runoff exits the Basin annually, and Laguna Lake storage fluctuations are considered minor compared to the total surface water budget. Surface water supply reservoirs are outside of the Basin boundary. Using the water budget equation, stream outflow is estimated as the difference between total surface water inflow and all other components of surface water outflow. Results of stream outflow calculations are presented in the main water budget Tables. There are limited annual stream flow records available for comparison to the estimates in the historical surface water budget. For the San Luis Valley subarea, the only applicable published records for stream outflow from the San Luis Valley subarea are two years of data recorded on Lower San Luis Obispo Creek at San Luis Bay Drive. In the 1971 water year, 20.46 inches of rainfall was recorded at Cal Poly and approximately 14,000 acre-feet of stream flow was reported at the San Luis Bay Drive gage (records missing in October). In the 1972 water year, 12.42 inches of rainfall was recorded at Cal Poly with 4,260 acre-feet of stream flow at the San Luis Bay Drive gage (San Luis Obispo County, 1974). These two years are outside of the historical water budget base period, and a comparison of flow for water years with similar precipitation suggests that the estimated Basin outflows are reasonable. Measured annual flows on Pismo Creek downstream of the Basin boundary are also available for only two water years, 1991 and 1992 (Balance Hydrologics, 2008). These are years within the historical base period, although the flows were measured at Highway 101, where Pismo Creek has a watershed of 38 square miles, compared to 25 square miles upstream of the Basin boundary. Estimated outflow in the water budget from the Edna Valley subarea for 1991 and 1992 are lower than the flows measured at Highway 101, as would be expected. Table 6-7 shows the stream outflow comparisons. Table 6-7: Stream Outflow Comparison. Precipitation Location Weary at Cal Poly Flow (in.) (acre—feet) San Luis Obispo Creek at San Luis Bay Drive gage 1971 20.46 13,705* San Luis Valley subarea stream outflow estimate 2003 22.9 15,390 San Luis Obispo Creek at San Luis Bay Drive gage 1972 12.42 4,260 San Luis Valley subarea stream outflow estimate 1990 13.36 3,360 Pismo Creek at Highway 101 gage 2,033 1991 18.6 Edna Valley subarea stream outflow estimate 1,840 Pismo Creek at Highway 101 gage 4,640 1992 22.14 Edna Valley subarea stream outflow estimate 3,590 *October 1970 missing — estimate 300 acre-feet = approx. 14,000 acre-feet for year 6.3.4 Historical Groundwater Budget The groundwater budget includes the following sources of inflow: • Infiltration of Precipitation • Groundwater -Surface Water Interaction • Subsurface Inflow • Infiltration of Applied Water 33 Page 270 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO The groundwater budget includes the following sources of outflow: • Groundwater Extractions • Subsurface Outflow • Groundwater -Surface Water Interaction 6.3.4.1 Components of Groundwater Inflow Infiltration of Precipitation Infiltration of precipitation refers to the amount of rainfall that directly recharges groundwater after moving through the soil and unsaturated zone (Figure 6-2). Direct measurement of infiltration has not been performed in the Basin, and estimates have been prepared based on prior work by Blaney (1933) in Ventura County Basins and Blaney et al. (1963) in the Lompoc Area. These studies involved soil moisture measurements at rainfall penetration test plots with various types of land cover, and the resulting deep percolation versus rainfall correlations have been considered applicable to central coast Basins (DWR, 2002; Fugro, 2002). The work by Blaney is several decades old, however, modeling efforts have shown the generalizations are relatively accurate for semi -arid climates (Rosenberg, 2001). The main advantage of Blaney's approach is that it is based on direct measurements of infiltration of precipitation. Criteria based on Blaney et al. (1963) were used for analytical water budgets in the Santa Maria Valley and Tri-Cities Mesa areas , where it was assumed that precipitation could infiltrate only in urban and agricultural areas when 11 inches of precipitation had fallen annually, and on areas of native vegetation when 17 inches of precipitation had fallen annually. Any amount of rainfall above 30 inches annually was not considered to contribute to deep percolation of precipitation, regardless of the land use classification (DWR, 2002). Correlations between infiltration and annual rainfall based on Blaney (1933) were also used for the 2002 Paso Robles groundwater Basin analytical water budget (Fugro, 2002). Estimates for infiltration of precipitation for the SLO Basin have been developed by applying Blaney correlations that restrict deep percolation to precipitation in agricultural areas that occurs after 11-12 inches of rainfall, and in native vegetation areas after approximately 18 inches of rainfall. Native vegetation was the most restrictive land cover for infiltration when tested by Blaney due to high initial soil moisture deficiencies. Urban areas were not part of the original studies by Blaney. The low permeability of hardscape (buildings and paving) limits infiltration and increases surface evaporation, compared to other types of land cover, but hardscape also increases runoff, which can lead to greater infiltration in adjacent areas receiving the runoff. Therefore, the infiltration threshold was set higher than irrigated agricultural land, but not as high as native grasslands. The Blaney correlation that produces infiltration between irrigated agriculture and native grassland is the curve for non -irrigated grain, with an infiltration threshold of approximately 14 inches of rainfall. Figure 6-15 plots the data collected by Blaney (1933). As with prior work by the DWR in northern Santa Barbara and southern San Luis Obispo Counties, rainfall above 30 inches was not considered to contribute to deep percolation in the Basin (DWR, 2002). Infiltration of precipitation results are shown in the water budget tables and graphs. 34 Page 271 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Rainfall vs. Infiltration (Blaney Correlations) 30 y = 1.4949x + 13.632 y = 1.228x + 14.397 y = 1.2348x + 11.632 y = 1.084x + 18.378 R2 = 0.7941 RZ = 0.9371 R2 = 0.8123 R2 = 0.9049 26 0,0 y = 1.2404x + 11.006 22 • R2 = 0.8275 ■ t • ■ u C c 18 .S X ■ 3 ♦ ♦ Citrus c ■ Deciduous a ♦ ♦ Truck, Alfalfa, Misc 14 X Non -irrigated Grain �♦ ♦♦ • Grass & Weeds ♦ Linear (Citrus) Linear (Deciduous) 10 — Linear (Truck, Alfalfa, Misc) — Linear (Non -irrigated Grain) Linear (Grass & Weeds) 6 — 0 2 4 6 8 10 12 Infiltration (inches) Blaney (1933) Figure 6-15: Rainfall vs Infiltration. 35 14 Page 272 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO The land use classifications for which infiltration thresholds have been developed for this GSP include citrus, deciduous, pasture, vegetable, vineyard, native brush/grassland (includes riparian corridors), wetland, urban developed/open space, and Urban turf. The minimum rainfall needed before infiltration of precipitation can occur for various land uses and covers are summarized in Table 6-8. Table 6-8: Minimum Rainfall for Infiltration. Land Use/Cover Infiltration Threshold (in.) Citrus 11.0 Deciduous 13.6 Pasture 11.6 Vegetable 11.6 Vineyard 13.6 Native brush/grassland 18.4 Wetland* 11.6 Urban developed/open space 14.4 Urban turf 11.6 * ET of precip. prior to runoff (no infiltration) Wetland soils are assumed to be close to field capacity due to shallow groundwater and the infiltration threshold is only used for estimating ET in the surface water budget, with the remaining precipitation as runoff (mainly into Laguna Lake). Groundwater -Surface Water Interaction (Net) As previously mentioned, groundwater -surface water Interaction involves both components of the surface water and groundwater budgets. The net interaction is an outflow component of the surface water budget and inflow component of the groundwater budget (losing streams). The groundwater -surface water interaction component is estimated using a mass balance approach for the Edna Valley subarea by adjusting the percent of stream inflow that percolates to groundwater (as Basin recharge) while minimizing the sum of squares of the residual error between the calculated change in storage and the measured change in storage (specific yield method) for multiple years. A similar optimization was performed for the San Luis Valley subarea except a variable percentage was used depending on the type of year (a greater percentage of stream flow percolation during lower rainfall years). A spill mechanism was developed in the budget to allow groundwater outflow to streams when storage reached full capacity, which was set to a nominal 37,000 acre-feet based on historical storage estimates using the specific yield method. The groundwater -surface water interaction estimates are in the water budget tables. Additional details of the calibration methodology used to minimize the residual error are presented in Change in Storage (Section 6.3.6). 36 Page 273 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Subsurface inflow Subsurface inflow from bedrock surrounding the groundwater Basin flows into both subareas. Subsurface inflows were estimated using Darcy's Law, which is an empirical formula describing the flow of fluid though a porous material, and expressed as: dh Q= —KA I Where: Q = groundwater discharge rate through a cross -sectional area of the porous material K= hydraulic conductivity of the material di= hydraulic gradient at the cross-section A = cross -sectional area The negative sign denotes that flow is in the direction of decreasing pressure. Since groundwater pressures are greater within the bedrock hills surrounding the Basin than beneath the alluvial valleys, there is subsurface inflow to the Basin from bedrock. Similarly, groundwater elevations in the Edna Valley subarea are greater than in the San Luis Valley subarea and the direction of subsurface flow is from the Edna Valley to the San Luis Valley. The application of Darcy's Law to estimate subsurface inflow from bedrock involves simplification and assumptions of uniformity in the subsurface. The Basin boundary was divided into six reaches, each representing different boundary conditions. Cross -sectional areas for boundary flows were based on the length of each reach times the average thickness of adjacent saturated Basin sediments determined from cross -sections presented in Chapter 4. Hydraulic gradients for each reach were developed by averaging topographic slopes between a line along the Basin boundary and a line drawn at a 5,000-foot setback from the Basin boundary, and assuming the hydraulic gradient paralleled these slopes. Hydraulic conductivity was estimated for each reach based on the bedrock type, a review of pumping test data in the SLO Basin Characterization Report (GSI, 2018), and structural features. Table 6-9 summarizes the results of subsurface inflow estimates. Bedrock subsurface inflow reaches are shown on Figure 6-16. Table 6-9: Subsurface Inflow Estimates. Reach Bedrock Formation Boundary description Length Thickness Hydraulic gradient Hydraulic conductivity Inflow ft ft ft/ft ft/day AFY 1 KJf melange w/serp. Depositional 43,900 100 0.05 0.05 90 2 Monterey/Lower Pismo Edna fault 38,100 200 0.01 0.03 30 3 KJf melange w/serp. Depositional 88,300 20 0.09 0.05 130 4 JKf metavolcanics Los Osos fault 28,600 40 0.09 0.2 220 5 KJf melange w/serp. Los Osos fault 12,200 60 0.05 0.05 20 6 Obispo/Rincon w/ serp. Depositional 9,500 60 0.06 0.05 10 Note: KJf - Fransiscan Assemblage Serp. = serpentinite AFY = acre-feet per year San Luis Valley subarea 320 Edna Valley subarea 110 Basin total 430 Basin boundary types for evaluating subsurface inflow are depositional or fault -bounded. Depositional boundaries occur where Basin sediments gradually thin toward the Basin boundary, while fault boundaries are where Basin sediments are abruptly offset by faulting. Fault boundaries are generally on the south side 37 Page 274 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) ♦ I Xs� r 11 ' ♦` �J, I'� r� .y T ` ; A� y _ n — , e .` can..•. x - .� -.l �� po. z � � � yy't.: � r. } 4 mx ., �. rt'' .' '� „}A j Y .0.; �ig1Y �♦ (� ,fir FT'-``` 3 _ rt g v Prepared For: N ( 11"', Au[hor, TK Date06/182020 0 0-5 1 1.5 rtY 0 0,5 1 1.5 2km SAN LUIS OBISPO VALLEY BASIN GSP F Explanation r-' SLO Valley Groundwater Basin Boundary --- Subarea Boundary Bedrock Subsurface Inflow Reach #1 #2 #3 #4 #5 #6 Geologic units and faults shown in Figure 4-8 References: Notes: Bedrock Subsurface Inflow Reaches 1. Coordinate System. State Plane California V FADS O405 Feet 1- 2. Projection'. Lambert Conformal Conic 2 3. H r-ortal Datum. NAD 83 3. 4. V rtic Datum: NAVD 88 5. Base air Dlbble (DF-129 DF-130, DF-210. DF-211, DF-212, DF-213, DF-214) Figure 6-16 38 Page 275 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO of the Basin, while depositional boundaries are on the north side (see geologic -cross sections in Chapter 4). Thicknesses at the Basin boundary are estimated from Basin cross -sections (Chapter 4). The hydraulic conductivity of bedrock across the Basin boundary was estimated at a nominal 0.05 feet per day, with two exceptions (Table 6-9). The Franciscan Assemblage metavolcanics are more permeable where fractured along the Los Osos fault zone (southwest Basin boundary; Figure 4-8), and are assigned a greater hydraulic conductivity. The Edna fault (Figure 4-8) offsets sedimentary beds along the Basin boundary and is interpreted to create a barrier to groundwater flow, corresponding to lower permeability. Subsurface inflow to the San Luis Valley subarea also takes place as Basin cross -flow from the Edna Valley subarea. A subsurface profile of the bedrock high was developed as part of this GSP using geophysical methods (CHG, 2019). Darcy's Law was used to estimate subsurface flow based on a cross -sectional area of 140,000 square feet (approximately 3,500 feet in length and 40 feet saturated depth), a typical hydraulic gradient perpendicular to the boundary of 0.004 feet per foot (average of high and low values from 1986 and 2019 water level contour maps) and an estimated hydraulic conductivity for the sediments of 7 ft/day from local pumping tests listed in the SLO Basin Characterization Report (GS1,2018). The resulting estimated average subsurface cross -flow from the Edna Valley subarea to the San Luis Valley subarea is 30 AFY. Infiltration of Applied Water (Return Flows) Estimates for infiltration of applied water include urban return flow and agricultural return flow. Urban return flow comes from water delivered for domestic or commercial/industrial uses that infiltrates to groundwater, mainly through landscape/turf irrigation and septic system discharges (includes suburban/rural residential return flow and recycled water return flow). Urban return flow does not include City wastewater that is discharged to San Luis Obispo Creek, which is accounted for in the surface water budget. Agricultural return flows come from applied irrigation water to crops. The first step in estimating urban return flows was to separate all delivered water (groundwater pumped from the Basin and imported surface water supplies) into indoor and outdoor use. An estimated 5 percent of indoor use is assumed to be consumptive use (95 percent return flow; EPA, 2008), while 85 percent of outdoor use is consumed (15 percent return flow) based on the typical range of estimates for other local Basins (DWR, 2002; Fugro, 2002). Almost all Indoor water use drains to septic systems or sewer systems. Outdoor water use is generally for irrigation, most of which evapotranspires into the atmosphere. The distribution of indoor to outdoor water use will vary based on the user. City customers are estimated to average 70 percent indoor use and 30 percent outdoor use, based on approximately 65 percent of delivered water reaching the wastewater treatment plant (with 5 percent indoor consumptive use). Large parcel residential water users outside of City limits tend to use a greater percentage of water for outdoor use than City residents. Businesses served by small water companies can have a wide range of indoor and outdoor distribution, and were assigned values based on the results of a local study on business water use (City of San Luis Obispo, 2000). The indoor and outdoor water use and associated return flows from water use by City, suburban/rural residential, and small water systems were compiled, together with estimated return flow from recycled water use. Infiltration of Applied Water estimates for urban and agricultural sectors are presented in the historical water budget Table 6-1, Table 6-2, and Table 6-3. 39 Page 276 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 6.3.4.2 Components of Groundwater Outflow Urban Groundwater Extractions Groundwater extraction from wells is the primary component of outflow in the groundwater budget. Estimates for historical pumping were derived from various sources, including purveyor records, land use data and water duty factors, and daily soil -moisture budgets. Available purveyor records (meter records) were obtained from the following Basin users: - City of San Luis Obispo - Golden State Water Company - Edna Valley East Mutual Water Company - Varian Ranch Mutual Water Company Production records ranged from weekly to quarterly, and were compiled to reflect the water year per GSP requirements. The City used groundwater from wells between 1989 and 2014, with the highest use in water years 1990, 1991, and 1992, averaging 1,830 AFY. Overall City groundwater use averaged 405 AFY between 1989 and 2014. Golden State Water Company averaged 335 AFY over the historical base period (1987-2019), although average water use over the last 5 water years is approximately 210 AFY. Edna Valley East MWC and Varian Ranch MWC have averaged approximately 100 AFY combined since reaching full development in the late 1990s, with 80 AFY combined over the last 5 years. There are also 42 small water systems, mostly in the San Luis Valley subarea, which use groundwater from wells. Each water system was assigned a use category, and a corresponding water use factor. For example, groundwater use for commercial service connections were assigned water use based on building square footage (from aerial image review), with a 0.06 acre-foot per year per square foot use factor. Water use factors for local use categories were obtained from the results of a study conducted by the City of San Luis Obispo utilities conservation office (SLO City, 2000). The water use estimate was developed for current conditions, as almost all water companies were active throughout the historical base period. The total amount of water used by small water systems in the Basin is estimated at 270 AFY, with the majority of use (260 AFY) in the San Luis Valley subarea. Less than 10 of the 42 small water systems using groundwater are connected to the City sewer. Urban groundwater extractions have also been used for golf course irrigation (turf). Laguna Lake golf course was served by groundwater wells through 2007, with recycled water use from the City beginning in 2008. San Luis Country Club uses a combination of recycled water use from County Service Area 18 and groundwater. The groundwater extractions and recycled water use components of urban turf irrigation are accounted for separately in the water budget. Estimates for turf irrigation water demand used the same daily soil moisture balance program as crop irrigation (see Agricultural Irrigation). Rural Residential Groundwater Extractions Rural residential groundwater use was estimated based on the number of residences identified on aerial images outside of water company service areas. Each rural residence was assigned a water use of 0.8 AFY, consistent with the San Luis Obispo County Master Water Plan (Carollo, 2012). As a comparison, the City study reported residential use for large parcels (>0.26 acres) at 0.6 AFY (City of San Luis Obispo, 2000), which is similar to the average estimated use per service connection in the Golden State Water Company service area over the historical base period. Water use per connection at Varian Ranch MWC and Edna Valley East MWC has ranged from 0.6 to 1.5 AFY, averaging approximately 1 acre-foot per year over the historical base period defined in Section 6.1.1. :o Page 277 of 1183 SLO Basin Groundwater5ustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Aerial images for 1986, 1994, 2009, and 2018 were reviewed for rural residential development. The estimated number of residences outside of water company service areas was compiled, and resulting computed rural residential water use for these years is presented in Table 6-10. Table 6-10: Rural Residential Water Use. SLO subarea Edna Subarea Basin Total Year Estimated Number of Residences' 1986 108 54 162 1994 119 61 180 2009 162 145 307 2018 173 158 331 Estimated Water Use (AFY)Z 1986 86 43 130 1994 95 49 144 2009 130 116 246 2018 138 126 265 'outside of water company service areas 2based on 0.8 AFY per residence Agricultural Groundwater Extractions Groundwater use for agricultural irrigation has been estimated using the DWR Consumptive Use Program Plus (CUP+; DWR, 2015) which is a crop water use estimator that uses a daily soil moisture balance. CUP+ was developed as part of the 2013 California Water Plan Update to help growers and agencies estimate the net irrigation water needed to produce a crop. Daily climate data from CIMIS Station #52 (San Luis Obispo) from 1986 to 2019 were used by the CUP+ program, along with estimates for various crop and soil parameters. The climate data is used to determine local reference evapotranspiration (ETo) on a daily basis. Crop coefficients are then estimated for up to four growth stages (initial, rapid, mid -season, late -season) which determine the crop evapotranspiration (ETc) values. Lastly, the CUP+ program uses variables related to the soil and crop type to determine the estimated applied water demand (ETaw), which is equivalent to the net irrigation requirement. Figure 6-17 shows the annual ETaw for various crops during the historical base period, along with the reference evapotranspiration (ETo) and precipitation at CIMIS Station #52. 41 Page 278 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5.00 4.50 4.00 17 3.50 w w LL 3.00 M E a 2.50 41 M M 2.00 d a a Q 1.50 1.00 0.50 0.00 Water Budget (§ 354.18) Consumptive Use of Applied Water (ETaw) h 49M '(9,� yP� h� 49^� y rymO. ON ON Oh O. ON ONO Nh 'O Year Vineyard ---O— Citrus f Deciduous f Vegetables f Pasture Turfgrass • • • • • CIMIS Precip (ft) • • • • • CIMIS ETO (ft) Figure 6-17: Consumptive Use of Applied Water. 42 Page 279 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Crop types were grouped according to the classification used by County Agricultural Commissioner's Office for crops overlying the Basin. These crop types included citrus, deciduous (non -vineyard), pasture, vegetable, and vineyard. A turf grass classification was added for estimating Urban sector water demand served by groundwater. The CUP+ program provides monthly water demand for each crop type during the hydrologic base period (1987-2019). Low, medium, and high consumptive use of applied irrigation water estimates are presented in Table 6-11. Low and high consumptive use are the respective annual minimum and maximum estimates over the base period, while medium consumptive use is the average. The CUP+ applied water requirement for vegetables was reduced by 40 percent to account for fallow acreage, which is not in production at any given time, based on historical aerial image review. Table 6-11: Consumptive Use of Applied Water. Crop Type Acre-feet per acre per year Low Med High Citrus 1.1 1.6 2.2 Deciduous 1.8 2.2 2.5 Pasture 2.6 3.1 3.7 Vegetables* 1.4 1.6 2.0 Vineyard 0.5 0.6 0.8 Turfgrass 1 2 2.6 4.1 *60 percent of ETaw to account for fallow fields As previously discussed in section 6.3.2 (Historical Land Use), the distribution of crop acreage was determined by a review and correlation of DWR and County crop surveys with aerial imagery. Crop acreages were interpolated between the years with data. Applied water demand volumes were calculated by multiplying the annual acreage for each crop by the average annual applied water demand during each year. The final applied water estimates used for the water budget were adjusted to include efficiency (with system leakage) factors of 80 percent for drip/micro emitter and high -efficiency sprinkler irrigation (citrus, deciduous, vineyard, and turfgrass) and 75 percent for mostly sprinkler with some drip irrigation (pasture and vegetables). The estimated groundwater extractions for agricultural water use are shown in the main water budget Table 6-1, Table 6-2, and Table 6-3. Wetland Direct ET There are approximately 570 acres of wetlands and open water in the San Luis Obispo subsurface (Table 6-6), of which approximately 100 acres are open water and 100 acres are wetlands directly connected to Laguna Lake (based on aerial image review) and part of the surface water budget. The remaining 370 acres of wetlands, most of which extend northwest of Laguna Lake into the Los Osos Valley, are assumed to be areas with seasonally shallow groundwater where evapotranspiration by native grasses effectively draws from the groundwater reservoir. The water demand of wetlands through direct groundwater use is assumed to be equivalent to average consumptive use of irrigated pasture as shown in Table 6-11. Any rainfall over 11.6 inches (Table 6-8) also contributes to meeting wetland water demand. Wetland direct ET estimates are shown in Table 6-1. Subsurface Outflow Subsurface outflow from Basin sediments occurs as underflow along the main creek channels (San Luis Obispo Creek and Pismo Creek). Outflow volumes were estimated using Darcy's Law (see Subsurface Inflow in Section 6.3.4.2). Table 6-12 presents the parameters used for subsurface outflow estimates. 43 Page 280 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Table 6-12: Subsurface Outflow Estimates. Water Budget (§ 354.18) Location Cross -sectional Area Hydraulic gradient Hydraulic conductivity Outflow ft2 ft/ft ft/day AFY San Luis Obispo Creek 46,800 0.004 65 100 Pismo Creek* 20,600 0.01 20 35 *begins at confluence of West Corral and East Corral de Piedra Creeks (Figure 4-2; Chapter 4) Cross sectional areas for outflow were based on the estimated width and saturated depth of alluvial deposits in the vicinity of where the creeks exit the groundwater Basin. Hydraulic gradients are the approximate grade of the stream channel, and the hydraulic conductivities are based on pumping tests (GSI, 2018; CHG, 2018). Additional subsurface outflow from the San Luis Valley subarea occurs along Davenport Creek and East Fork Creek, but would be significantly less than San Luis Obispo Creek due to shallower and less permeable alluvial deposits. Total average subsurface outflow from the San Luis Valley subarea is estimated at 100 AFY from San Luis Obispo Creek and a nominal 20 AFY from the smaller tributaries, for a total of 120 AFY. Subsurface outflow from the Edna Valley subarea along the Canada Verde drainage and tributaries is estimated to be similar to Pismo Creek (35 AFY), for a total subsurface outflow from that subarea of 90 AFY (35 AFY each from Pismo Creek and Canada Verde, and 20 AFY cross - flow through the bedrock high; see Subsurface Inflow section above). 6.3.5 Total Groundwater in Storage Groundwater is stored within the pore space of Basin sediments. The Specific yield is a ratio of the volume of pore water that will drain under the influence of gravity to the total volume of saturated sediments. The specific yield method for estimating groundwater in storage is the product of total saturated Basin volume and average specific yield. Calculation of total groundwater in storage for selected years was performed based on the specific yield method. Estimates of specific yield for Basin sediments were obtained based on a review of 21 representative well logs. The lithology for each well log was correlated with specific yield values reported for sediment types in San Luis Obispo County (Johnson, 1967). A summary of the correlations is shown in Table 6-13. Locations of well logs used for the specific yield correlations are shown in the referenced cross -sections from the SLO Basin Characterization Report (GSI, 2018). Groundwater in storage calculations were performed for the Spring conditions of 1986, 1990, 1995, 1998, 2011, 2014, and 2019 using the specific yield method. Water level contours for each year were prepared based on available water level data from various sources, including the County water level monitoring program, Geotracker Groundwater Information System data, groundwater monitoring reports, Stakeholder provided information, and Environmental Impact Reports. Water level contour maps for the Spring 1986 and Spring 2019 are shown in Figure 6-18 and Figure 6-19. The water level contours for storage calculations extend to the Basin boundaries. Groundwater levels in the San Luis Valley subarea may contour at, or slightly above, ground surface in areas where wetlands are present, and there are no major differences between Spring 1986 and Spring 2019 water levels. In the Edna Valley subarea, water level contours show some notable areas of decline between 1986 and 2019 near the intersection of Edna Road (Highway 227) and Biddle Ranch Road and at the southeast end of the Basin. Declines in these areas are also shown for other time intervals in Figure 5-8 and 5-9 of Chapter 5. Of note, however, is that Spring 2019 water levels shown in Figure 6-18 are lower near the intersection of FM Page 281 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Edna and Biddle Ranch Road than for the same period shown in Figure 5-6 (Chapter 5). This is because Figure 5-6 contours pressure in a shallow alluvial aquifer in this area while Figure 6-19 contours pressure in the deeper Pismo Formation aquifer that is the main supply aquifer for irrigation, and more appropriate for water budget storage calculations. Table 6-13: Specific Yield Averages. Well ID Basin Cross- Section Aquifer Specific Yield (percent) Qal QTp Pismo 139405 B-B' 3.0 4.7 158599 G-G' 6.8 6.9 18.0 279128 C2-C2' 11.0 279130 Al-A2 8.2 6.5 3.0 287786 C1-C1' 7.2 319126 C1-C1' 5.5 11.7 438979 Al-A2 4.4 8.1 469906 A3-A4 12.0 10.7 529099 E-E' 8.1 11.2 68734 A2-A3 5.9 8.0 710817 G-G' 3.0 5.0 10.8 73143 Al-A2 12.7 5.8 782309 A2-A3 7.1 10.5 15.8 782656 D-D' 5.0 16.0 e026022 H-H' 7.4 18.6 e0047435 G-G' 6.6 4.5 17.6 e0115806 offset I -I' 9.1 16.2 e0161526 F-F' 5.4 15.6 e0183287 H-H' 3.0 7.0 e0225875 A2-A3 3.6 17.3 10.1 TH1 C1-C1' 5.9 8.9 18.0 Average Specific Yield 6.2 8.5 13.4 Basin Average (weighted) 10.5 San Luis Valley Subarea (weighted) 8.0 Edna Valley Subarea (weighted) 11.7 Notes: Cross -sections shown in SLO Basin Characterization Report (GS1, 2018) Qal = alluvium; QTp = Paso Robles Formation; Pismo = Pismo Formation Weighted averages based on penetrated thicknesses of aquifer type. 45 Page 282 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) ' ,, ,�' �`� e ' •/'t Explanation r r .y�F � � � ' �: Aso a � �� ;, � � „�,� SLO Valley Groundwater ��•— ' .- � t _ Basin Boundary S i, o- 2A Subarea Boundary ,r 1 F r Groundwater Elevation Contour �60��.—� �' 15p��'� o,.•# '` °' (ft above mean sea level) - ff r n CD - Ln r III lei dw Iro EV w: 1 F r e 1 s Prepared For: N References: Notes: Groundwater Elevation Contours - 1. Projection System'. State Plane Conic mla V HIPS O405 Feet I- Spring g86 Au[hor_ TK I Coordinate o Lambert Conformal Conic 2. 7 0 0.25 0.5 0.75 1 rti iu Date 06/18/2020 4. V rrticaltal Dattumum NAD NAVD 883 3. 0 0.5 1 km 5. Base ap USGS 7 5' Topographic Map SA LUIS OBISPO VALLEY BASIN GSP m Figure 6-18 Page 283 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354,18) Explanation r J SLO Valley Groundwater Basin Boundary el00 -Subarea Boundary ~ Groundwater elevation contour 01 (ft above mean sea level) 76 7 00 , ♦ 78° �� Ski NA o O "y ��• I .,d 'r. .'• i 1 4 / r' 7 r ' 0 ' O 2 0 F- - w ... r � I, 220 Ap- c 7, 41 00 Prepared For: N References: Notes: Groundwater Elevation Contours - 1. Projection a con State Plane CaliConic mla V HIPS O405 Feet I- Spring 2l)1 9 Au[hor_ TK I Coordinate o Lambert Conformal Conic 2. 7 0 0.25 0.5 0.75 1 rti iu Date: 06/18/2020 4. V rrticaltDattal umu NAVD 88m NAD 3 3. 0 o.s km a Baseman uscs7sropograpnicMap Figure 6-19 SA N L UIS OBISPO VALLEY BA SIN G SP m WA Page 284 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) The water level contour maps and the base of permeable sediments were processed for volume calculation using Surfer, a grid -based mapping and graphic program. The methodology consisted of gridding and trimming surfaces to the Basin subarea boundaries, followed by volume calculation between surfaces. The gross volumes obtained were then multiplied by the representative specific yield for each subarea. An example of the methodology showing gridded surfaces for Spring 2019 water levels and the base of permeable sediments is presented in Figure 6-20. Estimated total storage volumes for selected years using the specific yield method are listed in Table 6-14. 0 Za0 200 Z00 �qq q 'zpq Spring 2019 Water Levels _01�'- L%J VV CrC JV rCr'/1\..0 Figure 6-20: Storage Volume Grids. !F3 Page 285 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Table 6-14: Spring Groundwater Storage Estimates. SLO Subarea Edna Subarea Basin Total Year Acre -Feet 1986 36,310 132,840 169,150 1990 31,560 119,950 151,510 1995 36,750 131,020 167,770 1998 36,990 133,010 170,000 2005 38,080 126,210 164,290 2011 35,910 120,220 156,130 2014 34,280 104,950 139,230 2019 34,940 105,630 140,570 Water Budget (§ 354.18) The groundwater storage estimates are much greater than previously reported, which was 23,300 acre-feet for the San Luis Valley subarea and 46,000 acre-feet for the Edna Valley subarea (Groundwater Basin Evaluation, Boyle Engineering, 1991). The Draft DWR study estimated an average storage of 16,000 acre- feet for the San Luis Valley subarea and 34,000 acre-feet for the Edna valley subarea (DWR, 1997). The increases are due primarily to improvements in characterizing Basin saturated thicknesses, specific yield, and methodology. For example, the average saturated thickness of Basin sediments in the Edna Valley is listed as 102.9 feet by Boyle (1991). For Spring 1990, the average thickness of saturated sediments in the Edna Valley subarea using the base of permeable sediments in the SLO Basin Characterization Report (GSI, 2018) and Surfer gridding methodology is estimated to be approximately 150 feet, an increase of 50 percent. The estimated average specific yield value for the Edna Valley subarea is also close to 30 percent greater for GSP storage calculations (11.7 percent) than the prior estimate (9.1 percent). An additional 30-35 percent decrease in Basin storage areas was also incorporated into the prior methodology through the application of a subsurface configuration factor, which was not clearly described. (Boyle, 1991). Increases in total groundwater in storage between prior work and current estimates does not imply an increase in sustainable yield or basin recharge rate. The purpose of total storage estimates for the water budget is to provide an independent calculation of change in storage over time, which is a critical part of the water budget equation. 6.3.6 Change in Storage Balancing the water budget final step in water budget development. As previously mentioned, the water budget equation is as follows: INFLOW — OUTFLOW = CHANGE IN STORAGE The annual change in storage for the surface water budget is assumed to be zero, as surface flow moves quickly through the basin and any differences in storage are minor compared to the total budget. Therefore, the surface water balance equation can be simplified as INFLOW = OUTFLOW, and was used to estimate the stream outflow component of the surface water budget. For the groundwater budget, groundwater -surface water interaction (as stream flow seepage) was adjusted to approximate the change in storage calculated using the specific yield method discussed above. The difference between the estimated change in storage shown in the water budget and the measured change in storage using the specific yield method is the mass balance error. Change in storage is reported between seasonal high (Spring) conditions per GSP regulations. • Page 286 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO Change in storage and mass balance error for the groundwater budget is shown in Table 6-15. Figure 6-21 shows total storage using the water budget and specific yield method. Table 6-15: Change in Storage Comparison — Historical Base Period 1987 — 2019. Subarea water Budget Specific Yield Method Mass Balance Error Change in Storage (acre-feet) acre-feet AFY Percent* San Luis Valley subarea 690 -1,370 2,060 62 6 Edna Valley Subarea -27,440 -27,210 -230 -7 0 *Percent of total subarea water budget The difference in change in storage estimates between the water budget and the specific yield method is approximately 60 AFY for the San Luis Valley subarea over the historical base. The water budget estimates a 690 acre-foot gain in storage, compared to a 1,370 acre-foot decline in storage using the specific yield method. A review of the contour maps indicates that the decline in San Luis Valley subarea storage shown by the specific yield method is due to the effects of groundwater level declines in the Edna Valley subarea being contoured across the bedrock high into the San Luis Valley subarea (Figure 6-18 and Figure 6-19). There are no hydrographs for water levels in the bedrock high area, and the extent to which water level declines in the Edna Valley subarea have influenced water levels in the eastern portion of the San Luis Valley subarea is uncertain. Available water level hydrographs do not show overall water level declines west of the bedrock high (Figure 5-11; Chapter 5). The difference in change in storage estimates between the water budget and the specific yield method is less than 10 AFY for the Edna Valley subarea over the historical base period. The water budget estimates a 27,440 acre-foot decline in storage, compared to a 27,210 acre-foot decline in storage using the specific yield method. The change in storage mass balance error for the Basin historical groundwater budget is less than 100 acre-feet per year, which is reasonable for the purposes of preliminary sustainable yield estimates. 50 Page 287 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO iCi1I1I1III i r.1111lIlI1] 100000 80000 to M O N Ln C 60000 m 3 c 0 L7 40000 20000 0 1980 Groundwater Storage Estimate Comparison 1985 1990 1995 2000 2005 Water Year 2010 2015 2020 --*--SLO Water Budget Method f5LO Specific Yield method —&--LDNA Water Budget —0—LDNA SpecifiicYieId Method Figure 6-21: Groundwater Storage Estimate Comparison for Basin Subareas. 51 2025 Page 288 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 6.3.7 Preliminary Sustainable Yield Estimate The sustainable yield is the maximum quantity of water, calculated over a base period representative of long-term conditions in the Basin and including any temporary surplus, that can be withdrawn annually from a groundwater supply without causing an undesirable result. Temporary surplus is the amount of water that may be pumped from an aquifer to make room to store future water that would otherwise be wasted and unavailable for use. Undesirable results will be defined for six sustainable management criteria in Chapter 7. Examples of potential undesirable results are related to long-term declines in water levels and associated loss in groundwater in storage. Estimating sustainable yield includes evaluating historical, current, and projected water budget conditions. The analytical water budget method utilized in this analysis evaluates historical and current conditions, and provides a preliminary estimate for the Basin sustainable yield. The projected water budget will be evaluated using the Basin numerical model presented later in the projected water budget section of the chapter, at which time the minimum thresholds for the sustainable management criteria can be incorporated and the final sustainable yield will be determined. The preliminary Sustainability estimate can be used for planning potential projects and management action scenarios for the Basin numerical model. The preliminary sustainable yield of the San Luis Obispo groundwater Basin has been estimated separately for each of the subareas. The Edna Valley subarea has experienced cumulative storage declines since 1998, while the San Luis Valley subarea experiences storage declines during drought, but recovers and is typically close to full storage capacity (Figure 6-21). For the Edna Valley subarea, sustainable yield is estimated as the amount of long-term recharge (groundwater inflow) to the Basin over the historical base period (3,400 AFY) minus subsurface outflow (100 AFY). The resulting preliminary sustainable yield is estimated at a 3,300 AFY. The San Luis Valley subarea has not experienced cumulative and persistent storage declines. Long-term average recharge to groundwater in the San Luis Valley subarea is estimated to be 3,700 AFY, of which an estimated 1,200 AFY is used by wetlands, leaving 2,500 AFY for withdrawal without long-term declines in storage (subsurface outflow is supported by wastewater discharges). The historical recharge to the subarea may be less than the sustainable yield, however, because average annual recharge can increase with storage declines, particularly in a Basin that is at or near storage capacity. The San Luis Valley subarea did experience significant undesirable results due to land subsidence during the period of high groundwater use and associated storage decline toward the end of the 1987-91 drought. Average groundwater production from 1990-1992 was 3,960 AFY. Land subsidence is not necessarily a risk over the entire subarea, and would generally require historical storage declines to be exceeded in affected areas for addition subsidence to occur. However, without mitigation for land subsidence or specific projects that increase recharge during dry periods, the preliminary sustainable yield of the San Luis Valley subarea is estimated at 2,500 AFY, based on the long-term average recharge of 3,700 AFY minus 1,200 AFY used by wetlands. Table 6-15 summarizes the preliminary sustainable yield estimates. Table 6-16: Preliminary Sustainable Yield Estimate (AFY). San Luis Valley Subarea 2,500 Edna Valley Subarea 3,300 Basin Total 5,800 52 Page 289 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO The above values are lower overall than historical estimates by Boyle (1991) and DWR (1997 Draft). Boyle estimated 5,900 AFY of sustainable yield for the Basin while DWR estimated 2,000-2,500 for the San Luis Valley subarea and 4,000-4,500 for the Edna Valley Subarea. 6.3.8 Quantification of Overdraft Overdraft is the condition of a groundwater Basin or subbasin where the amount of water withdrawn by pumping exceeds the amount of water that recharges a Basin over a period of years, during which the water supply conditions approximate average conditions. While the 33-year historical base period is representative of the long-term climatic conditions needed for estimating sustainable yield, a shorter period is appropriate for characterizing water supply conditions with respect to Basin withdrawals and overdraft. Over the last 10 years the City has introduced recycled water reuse at Laguna golf course (historically irrigated by groundwater) and has stopped pumping groundwater from the San Luis Valley subarea, while total irrigated agriculture in the Edna Valley subarea has leveled off, after increasing from the beginning of the historical base period through the mid-2000's (Table 6-5). Overdraft for GSP planning purposes has been estimated as the difference between sustainable yield and average groundwater withdrawals over the last 10 years (2010-2019), with an adjustment in the San Luis Valley subarea to account for reductions in agricultural acreage due to recent development. Groundwater extractions in the San Luis Valley subarea (adjusted for recent development) have averaged 1,800 AFY since 2010, which is 700 AFY less than the average recharge of 2,500 AFY over the same representative period, indicating a surplus of groundwater for the subarea. In the Edna Valley subarea, groundwater pumping has averaged 4,400 AFY since 2010, which is 1,100 AFY more than the sustainable yield of 3,300 AFY for the subarea. The Edna Valley subarea is an estimated 1,100 AFY in overdraft. Total Basin overdraft is estimated at 400 AFY. Table 6-16 summarizes the overdraft estimates. Table 6-17: Estimated Overdraft (AFY). San Luis Valley Subarea -700* Edna Valley Subarea 1,100 Basin Total 400 *surplus In comparison, prior work by Boyle (1991) concluded that there was short-term overdraft in the Basin and that withdrawals in excess of sustainable yield was a common occurrence. However, during the period from 1978-1990, the Basin was not considered in a state of sustained overdraft. The Draft 1997 DWR study does not address overdraft, although there is a net deficit in the basin water budget for the 1969-1977 base period, a surplus for the 1983 water budget, and a deficit for the 1990 water budget. The draft DWR report concluded that additional water beyond the long-term dependable yield could be extracted from the Basin, but that there could be adverse impacts. 6.4 CURRENT WATER BUDGET The current water budget quantifies inflows and outflows for the Basin based on the last four years of the historical water budget, from 2016 to 2019. These years provide the most recent population, land use, and hydrologic conditions. Recent Basin conditions have been characterized by above average rainfall, along with a decrease in urban extractions and imported surface water supplies assumed to be associated with greater conservation awareness by the public during the 2012-2016 drought. There have also been declines in agricultural acreage and associated groundwater extractions in the San Luis Valley subarea associated with urban development. 53 Page 290 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) Comparisons of the current water budget to the 1987-2019 historical surface water budget used for the preliminary sustainable yield estimates for the two subareas and total Basin are shown in Table 6-17 through Table 6-19. Bar graphs are shown in Figure 6-22 through Figure 6-27. As expected, the average annual water budget inflows and outflows are greater under current conditions than the historical base period, primarily due to greater rainfall. There has been more groundwater inflow than outflow under the current water budget in the San Luis Valley subarea, leading to increased groundwater in storage. In the Edna valley subarea, the outflow has been slightly greater than inflow under the current water budget, with relatively little change to groundwater in storage since the end of the recent drought (Figure 6-21). As noted above, groundwater extractions for agriculture in the San Luis Valley subarea have declined between the historical and current water budgets. 54 Page 291 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Water Budget (§ 354.18) Table 6-18: Current Water Budget - San Luis Valley Subarea. SAN LUIS VALLEY SUBAREA SURFACE WATER BUDGET Historical Average (1987-2019) Current (2016-2019) Inflow AFY Precipitation 10,580 12,280 Groundwater extractions (Urban) 740 400 Groundwater extractions (Ag) 1,630 1,370 Stream Inflow at Basin Boundaries 10,720 10,570 Wastewater discharge to streams 4,080 3,910 Local Imported Supplies 5,820 5,430 TOTAL IN 33,580 33,960 Outflow ET of precipitation 7,770 8,220 ET of Applied Water (Urban) 2,050 1,510 ET of Applied Water (Ag) 1,310 1,100 ET of Lake/Wetland/Riparian 650 690 Surface Water Delivery Offset 4,080 3,910 Infiltration of Precipitation 1,610 3,190 Infiltration of Applied Water (Urban) 440 440 Infiltration of Applied Water (ag) 320 260 GW-SW interaction (net) 970 510 Stream outflow at Basin boundary 14,390 14,120 TOTAL OUT 33,580 33,960 GROUNDWATER BUDGET Historical Average (1987-2019) Current (2016-2019) Inflow AFY Infiltration of precipitation 1,610 3,190 Urban water return flow 440 440 Agricultural return flow 320 260 GW-SW interaction (net) 970 510 Subsurface from bedrock 340 340 TOTAL IN 3,670 4,750 Outflow Groundwater extractions (Urban) 740 400 Groundwater extractions (Ag) 1,630 1,370 Wetland direct ET 1,160 1,190 Subsurface outflow 120 120 TOTAL OUT 3,650 3,080 55 Page 292 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Water Budget (§ 354.18) Table 6-19: Current Water Budget - Edna Valley Subarea. EDNA VALLEY SUBAREA SURFACE WATER BUDGET Historical (1987-2019) Current (2016-2019) Inflow AFY Precipitation 9,300 10,780 Groundwater extractions (Urban) 880 820 Groundwater extractions (Ag) 3,210 3,440 Stream Inflow at Basin Boundaries 3,630 3,480 TOTAL IN 17,020 18,520 Outflow ET of precipitation 6,910 7,200 ET of Applied Water (Urban) 600 610 ET of Applied Water (Ag) 2,650 2,870 ET of Riparian 40 40 Infiltration of Precipitation 1,890 2,800 Infiltration of Applied Water (Urban) 280 210 Infiltration of Applied Water (ag) 560 570 GW-SW interaction (net) 510 490 Stream outflow at Basin boundary 3,580 3,750 TOTAL OUT 17,020 18,520 GROUNDWATER BUDGET Historical Average (1987-2019) Current (2016-2019) Inflow AFY Infiltration of precipitation 1,890 2,800 Urban water return flow 290 220 Agricultural return flow 560 570 GW-SW interaction (net) 510 490 Subsurface from bedrock 110 110 TOTAL IN 3,360 4,180 Outflow Groundwater extractions (Urban) 880 820 Groundwater extractions (Ag) 3,210 3,440 Subsurface outflow 100 100 TOTAL OUT 4,190 4,360 56 Page 293 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Table 6-20: Current Water Budget - Basin Total. Water Budget (§ 354.18) BASIN TOTAL SURFACE WATER BUDGET Historical Average (1987-2019) Current (2016-2019) Inflow AFY Precipitation 19,880 23,060 Groundwater extractions (Urban) 1,620 1,220 Groundwater extractions (Ag) 4,840 4,810 Stream Inflow at Basin Boundaries 14,350 14,050 Wastewater discharge to streams 4,080 3,910 Local Imported Supplies 5,820 5,430 TOTAL IN 50,600 52,480 Outflow ET of precipitation 14,680 15,420 ET of Applied Water (Urban) 21650 2,120 ET of Applied Water (Ag) 3,960 3,970 ET of Lake/Wetland/Riparian 690 730 Surface Water Delivery Offset 4,080 3,910 Infiltration of Precipitation 3,500 5,990 Infiltration of Applied Water (Urban) 720 650 Infiltration of Applied Water (ag) 880 830 GW-SW interaction (net) 1,480 1,000 Stream outflow at Basin boundary 17,970 17,870 TOTAL OUT 50,600 52,480 GROUNDWATER BUDGET Historical Average (1987-2019) Current (2016-2019) Inflow AFY Infiltration of precipitation 3,500 5,990 Urban water return flow 730 660 Agricultural return flow 880 830 GW-SW interaction (net) 1,480 1,000 Subsurface from bedrock 450 450 TOTAL IN 7,030 8,930 Outflow Groundwater extractions (Urban) 1,620 1,220 Groundwater extractions (Ag) 4,840 4,810 Wetland direct ET 1,160 1,190 Subsurface outflow 220 220 TOTAL OUT 7,840 7,440 57 Page 294 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 30,000 20,000 4P d- 10,000 47 V f6 N 0 O l6 c-10,000 Q -20,000 -30,000 -40,000 Water Budget (§ 354.18) Historical and Current Average Annual Surface Water Budget San Luis Valley Subarea Historical Average (1987-2019) Current (2016-2019) ■ Precipitation (+) ■ Wastewater Discharge+) ■ Infiltration of Precipitation-) ■ GW-SW Interaction (-) ■ Groundwater Extraction+) ■ Imported Supplies (+) ■ Applied Water Inflitration -) ■ Surface Water Deliveries Offset(-) ■ Stream inflow (+) ■ Evapotranspiration-) ■ Stream outflow (-) Figure 6-22: Historical and Current Average Annual Surface Water Budget — San Luis Valley Subarea. 58 Page 295 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO 25,000 15,000 m 5,000 V f6 c -5,000 c a 1111111111111l128 III] -15,000 1 U 1 -25,000 Historical and Current Average Annual Surface Water Budget Edna Valley Subarea Historical Average (1987-2019) Current (2016-2019) ■ Precipitation (+) ■ Groundwater Extraction (+) ■ Stream Inflow (+) ■ Evapotranspiration-) ■ Infiltration of Precipitation-) ■ Applied Water Inflitration-) ■ Stream outflow (-) ■ GW-SW Interaction (-) Figure 6-23: Historical and Current Average Annual Surface Water Budget — Edna Valley Subarea. 59 Page 296 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 60,000 40,000 V !6 a -20,000 -40,000 -60,000 Water Budget (§ 354.18) Historical and Current Average Annual Surface Water Budget Basin Total Historical Average (1987-2019) Current (2016-2019) ■ Precipitation (+) ■ Wastewater Discharge+) ■ Infiltration of Precipitation-) ■ GW-SW Interaction (-) ■ Groundwater Extraction+) ■ Imported Supplies (+) ■ Applied Water Inflitration -) ■ Surface Water Deliveries Offset(-) ■ Stream Inflow (+) ■ Evapotranspiration-) ■ Stream Outflow (-) Figure 6-24: Historical and Current Average Annual Surface Water Budget — Basin Total. .f Page 297 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 6,000 5,000 4,000 3,000 2,000 oT w 1,000 E 7 0 m a -1,000 -2,000 -3,000 -4,000 -5,000 Water Budget (§ 354.18) Historical and Current Average Annual Groundwater Budget San Luis Valley Subarea Historical Average (1987-2019) Current (2016-2019) ■ Infiltration of Precipitation+) ■ Infiltration of Applied Water+) ■ GW-SW Interaction+) ■ Subsurface Inflow (+) ■ Groundwater Extraction-) ■ Wetland direct ET-) Subsurface Outflow(-) Figure 6-25: Historical and Current Average Annual Groundwater Budget — San Luis Valley Subarea. 61 Page 298 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 5,000 4,000 3,000 2,000 4T 1,000 m m 0 0 7 -1,000 c a -2,000 -3,000 -4,000 -5,000 Water Budget (§ 354.18) Historical and Current Average Annual Groundwater Budget Historical Average (1987-2019) Current (2016-2019) ■ Infiltration of Precipitation+) ■ Infiltration of Applied Water+) ■ GW-SW Interaction+) ■ Subsurface Inflow (+) ■ Groundwater Extraction (-) Subsurface Outflow-) Figure 6-26: Historical and Current Average Annual Groundwater Budget — Edna Valley Subarea. 62 Page 299 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 10,000 8,000 6,000 4,000 a� 2,000 m V !6 f6 -2,000 C a -4,000 -6,000 -8,000 -10,000 Water Budget (§ 354.18) Historical and Current Average Annual Groundwater Budget Basin Total Historical Average (1987-2019) Current (2016-2019) ■ Infiltration of Precipitation+) ■ Infiltration of Applied Water+) ■ GW-SW Interaction+) ■ Subsurface Inflow+) ■ Groundwater Extraction-) ■ Subsurface Outflow-) ■ Wetland direct ET Figure 6-27: Historical and Current Average Annual Groundwater Budget — Basin Total. 63 Page 300 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 6.5 PROJECTED WATER BUDGET 6.5.1 Assumptions 6.5.2 Inflows 6.5.3 Outflows 6.5.4 Change In Storage Water Budget (§ 354.18) Page 301 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO REFERENCES Water Budget (§ 354.18) Balance Hydrologics. 2008. Hydrology and Geology Assessment of the Pismo Creek Watershed, San Luis Obispo County, California. 2008. Blaney. 1963. Utilization of the Water of the Santa Ynez River Basin in Southern Santa Barbara County California, United Stated Deparment of Agriculture. 1963. -. 1933. Ventura County Investigation, Bulletin No. 46, California Deparment of Public Works, Division of Water Resources. 1933. Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. CIMS. 2019. Station 52, San Luis Obispo - Central Coast Valleys. 2019. City of San Luis Obispo. 2016. 2015 Urban Water Management Plan. 2016. -. 2018. General Plan. 2018. -. 2015. Water Resources Status Report. 2015. -. 2000. Water Use Factors. 2000. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. -. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists. 2018. Groundwater Flow Analysis, Recycled Water Recharge Project, San Luis Valley Subarea, San Luis Obispo Valley Groundwater Basin. 2018. -. 2019. Optional Task 2.4B Geophysical Survey. 2019. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. -. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. -. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2015. Consumptive Use Program Plus (CUP+) Model, in California Water Plan Update 2013, Volume 4. Reference Guide, Developed by DWR and UC Davis. 2015. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. 65 Page 302 of 1183 SLO Basin Groundwater Sustainability Plan Water Budget (§ 354.18) County of SLO and City of SLO -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 1996. South Central Coast Land Use Survey. 1996. -. 1987. Southern Central Coast Land Use Survey, 1985. Morro Bay South 54-30 and San Luis Obispo 54-31 Survey Maps. 1987. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. -. 2016. Water Budget Best Management Practices for the Sustainable Management of Groundwater. 2016. -. 2002. Water Resources of the Arroyo Grande - Nipomo Mesa Area. 2002. EPA. 2008. Water Sense Factsheet - Indoor Water Use in the United States, EPA-832-F-06-004, 2008. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study, September. 1994. Fugro West and Cleath & Associates. 2002. Paso Robles Groudnwater Study, Final Report. 2002. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. Hall, C.A. 1979. Geologic map of the San Luis Obispo - San Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. -. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. ITRC. 2020. Official Cal Poly Precipitation Data, Cal Poly/NOAA Station Rain Gage. 2020. Johnson, A.I. 1967. Specific Yield - Compilation of Specific Yield for Various Materials, U.S. Geological Survey Water -Supply Paper 1662-D, prepared in cooperation with the California Deparment of Water Resources. 1967. National Land Cover Database. Multi -Resolution Land Characteristics Consortium. 2016. Multi -Resolution Land Characteristics Consortium. Rosenberg, L.I. 2001. Potential Aquifer Recharge Areas: Monterey County, California. s.l.: Monterey County Planning Department, 2001. San Luis Obispo County Deparment of Agriculture/Weights and Measures. 2019. Crop Surveys for San Luis Obispo Valley Groundwater Basin 2013-2018. 2019. San Luis Obispo County Department of Public Works. 2020. Andrews Street Bridge Stream Flow Gage 745. 2020. -. 2020. Gas Company Rain Sensor 3099. 2020. San Luis Obispo County Engineering Department. 1974. Hydrologic & Climatological Data, Seasons of 1970-71 & 1971-72. 1974. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. SWRCB. 1990. Ernest Righetti & Sons Application 28883, Decision 1627. 1990. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.l.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. M. Page 303 of 1183 SLO Basin Groundwater5ustainability Plan County of SLO and City of SLO Water Budget (§ 354.18) 67 Page 304 of 1183 DRAFT Chapter 7 - Monitoring Networks San Luis Obispo Valley Basin Groundwater Sustainability Plan Available for viewing in the December 9, 2020 Agenda Packet: Dec 2, 2020 Recommended the GSAs to receive and file for public comments: Dec 9, 2020 Available for public comments on www.slowaterbasin.com: Dec 11, 2020 Close of public comment period: Jan 30, 2021 Per the GSC's recommendation on December 9, 2020, the Draft Chapter 7- Monitoring Networks will be distributed to the City and County GSAs to receive and file. This Draft document is also posted on the online portal: www.slowaterbasin.com for public comments. Comments from the public are being collected using a comment form available at www.slowaterbasin.com by clicking on "Submit Comment". If you require a paper form to submit by postal mail, please contact your local Groundwater Sustainability Agency (GSA). Page 305 of 1183 Groundwater Sustainability Plan Chapter 7 — Monitoring Networks forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by '00"'b-wsc WATER SYSTEMS CONSULTING, INC. `_J\ z`'HG is '/ FGS1 GEI Consultants Stillwate- Sciences Water solutions, Inc 12/2/2020 Page 306 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO TABLE OF CONTENTS Table of Contents Listof Figures................................................................................................................................................. i Tables........................................................................................................................................................... iv Appendices.................................................................................................................................................... v Listof Terms Used........................................................................................................................................ vi ExecutiveSummary....................................................................................................................................... 1 1 Introduction to the SLO Basin GSP......................................................................................................... 1.1 Purpose of the Groundwater Sustainability Plan............................................................................ 1.2 Description of SLO Basin................................................................................................................. 1.3 Basin Prioritization.......................................................................................................................... 2 Agency Information (§ 354.6)................................................................................................................ 2.1 Agencies Names and Mailing Addresses......................................................................................... 2.2 Agencies Organization and Management Structures..................................................................... 2.2.1 County of San Luis Obispo....................................................................................................... 2.2.2 City of San Luis Obispo............................................................................................................ 2.2.3 Other Participating Parties in the MOA.................................................................................. 2.2.3.1 Edna Valley Growers Mutual Water Company............................................................... 2.2.3.2 Varian Ranch Mutual Water Company........................................................................... 2.2.3.3 Edna Ranch Mutual Water Company.............................................................................. 2.2.3.4 Golden State Water Company........................................................................................ 2.3 Authority of Agencies...................................................................................................................... 2.3.1 Groundwater Sustainability Agencies..................................................................................... 2.3.1.1 County of San Luis Obispo............................................................................................... 2.3.1.2 City of San Luis Obispo.................................................................................................... 2.3.2 Memorandum of Agreement.................................................................................................. 2.3.3 Coordination Agreements....................................................................................................... 2.4 Contact information for Plan Manager........................................................................................... 3 Description of Plan Area (§ 354.8)......................................................................................................... 3.1 SLO Basin Introduction.................................................................................................................... 3.2 Adjudicated Areas........................................................................................................................... 3.3 Jurisdictional Areas......................................................................................................................... 3.3.1 Federal Jurisdictions................................................................................................................ 3.3.2 Tribal Jurisdiction.................................................................................................................... i Page 307 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.3.3 State Jurisdictions................................................................................................................... 3.3.4 County Jurisdictions................................................................................................................ 3.3.5 City and Local Jurisdictions..................................................................................................... 3.3.6 Special Districts....................................................................................................................... 3.4 Land Use.......................................................................................................................................... 3.4.1 Water Source Types................................................................................................................ 3.4.2 Water Use Sectors................................................................................................................... 3.5 Density of Wells.............................................................................................................................. 3.6 Existing Monitoring and Management Programs........................................................................... 3.6.1 Groundwater Monitoring........................................................................................................ 3.6.1.1 Groundwater Level Monitoring..................................................................................... 3.6.1.2 Groundwater Quality Monitoring.................................................................................. 3.6.1.3 Surface Water Monitoring.............................................................................................. 3.6.1.4 Climate Monitoring......................................................................................................... 3.6.2 Existing Management Plans.................................................................................................... 3.6.2.1 SLO Basin Characterization and Monitoring Well Installation ........................................ 3.6.2.2 San Luis Obispo County Master Water Report(2012).................................................... 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014)............. 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan (2016) ........................... 3.6.3 Existing Groundwater Regulatory Programs............................................................................ 3.6.3.1 Groundwater Export Ordinance (2015).......................................................................... 3.6.3.2 Well Ordinances, County and City.................................................................................. 3.6.3.3 Countywide Water Conservation Program Resolution 2015-288 (2015) ....................... 3.6.3.4 Agricultural Order R3-2017-002 (2017).......................................................................... 3.6.3.5 Water Quality Control Plan for the Central Coast Basins(2017).................................... 3.6.3.6 California DWR Well Standards (1991)........................................................................... 3.6.3.7 Requirements for New Wells(2017)............................................................................... 3.6.3.8 Title 22 Drinking Water Program(2018)......................................................................... 3.6.3.9 Waterway Management Plan — San Luis Obispo Creek Watershed (2003).................... 3.6.3.10 Incorporation Into GSP.................................................................................................... 3.6.3.11 Limits to Operational Flexibility...................................................................................... 3.7 Conjunctive Use Programs.............................................................................................................. 3.8 Land Use Plans................................................................................................................................ 3.8.1 City of San Luis Obispo General Plan...................................................................................... 3.8.2 County of San Luis Obispo General Plan................................................................................. ii Page 308 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 3.8.3 Los Ranchos/Edna Village Plan................................................................................................ 3.8.4 Plan Implementation Effects on Existing Land Use................................................................. 3.8.5 Plan Implementation Effects on Water Supply....................................................................... 3.8.6 Well Permitting....................................................................................................................... 3.8.7 Land Use Plans Outside of Basin............................................................................................. 3.9 Management Areas......................................................................................................................... 3.9.1 Reason for Creation................................................................................................................ 3.10 Additional GSP Elements, if Applicable........................................................................................... 4 Basin Setting (§ 354.14)......................................................................................................................... 4.1 Basin Topography and Boundaries................................................................................................. 4.2 Primary Users of Groundwater....................................................................................................... 4.3 Soils Infiltration Potential................................................................................................................ 4.4 Regional Geology............................................................................................................................ 4.4.1 Regional Geologic Structures.................................................................................................. 4.4.2 Geologic Formations within the Basin.................................................................................... 4.4.2.1 Alluvium.......................................................................................................................... 4.4.2.2 Paso Robles Formation................................................................................................... 4.4.2.3 Pismo Formation............................................................................................................. 4.4.3 Geologic Formations Surrounding the Basin.......................................................................... 4.4.3.1 Monterey Formation....................................................................................................... 4.4.3.2 Obispo Formation........................................................................................................... 4.4.3.3 Franciscan Assemblage................................................................................................... 4.5 Principal Aquifers and Aquitards.................................................................................................... 4.5.1 Cross Sections......................................................................................................................... 4.5.2 Aquifer Characteristics............................................................................................................ 4.5.3 Aquitards................................................................................................................................. 4.6 Surface Water Bodies...................................................................................................................... 4.7 Subsidence Potential....................................................................................................................... 5 Groundwater Conditions (§ 354.16)...................................................................................................... 5.1 Groundwater Elevations and Intepretation.................................................................................... 5.1.1 Fall 1954 Groundwater Elevations.......................................................................................... 5.1.2 Spring 1990 Groundwater Elevations..................................................................................... 5.1.3 Modeled 1990s Groundwater Elevations............................................................................... 5.1.4 Spring 1997 Groundwater Elevations..................................................................................... 5.1.5 Spring 2011 Groundwater Elevations..................................................................................... Page 309 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 5.1.6 Spring 2015 Groundwater Elevations..................................................................................... 5.1.7 Spring 2019 Groundwater Elevations..................................................................................... 5.1.8 Fall 2019 Groundwater Elevations.......................................................................................... 5.1.9 Changes in Groundwater Elevation........................................................................................ 5.1.10 Vertical Groundwater Gradients............................................................................................. 5.2 Groundwater Elevation Hydrographs............................................................................................. 5.3 Groundwater Recharge and Discharge Areas................................................................................. 5.3.1 Groundwater Recharge Areas................................................................................................. 5.3.1.1 Infiltration of Precipitation............................................................................................. 5.3.1.2 Subsurface Inflow............................................................................................................ 5.3.1.3 Percolation of Streamflow.............................................................................................. 5.3.1.4 Anthropogenic Recharge................................................................................................ 5.3.2 Groundwater Discharge Areas................................................................................................ 5.4 Change in Groundwater Storage..................................................................................................... 5.5 Seawater Intrusion.......................................................................................................................... 5.6 Subsidence...................................................................................................................................... 5.7 Interconnected Surface Water........................................................................................................ 5.7.1 Depletion of Interconnected Surface Water........................................................................... 5.8 Potential groundwater dependent ecosystems.............................................................................. 5.8.1 Hydrology................................................................................................................................ 5.8.1.1 Overview of GDE Relevant Surface and Groundwater Hydrology .................................. 5.8.1.2 Losing and Gaining Reaches............................................................................................ 5.8.2 Vegetation and Wetland Groundwater Dependent Ecosystem Identification ....................... 5.8.3 Identification of Special -Status Species and Sensitive Natural Communities Associates withGDE's.............................................................................................................................................. 5.9 Groundwater Quality Distribution and Trends............................................................................... 5.9.1 Groundwater Quality Suitability for Drinking Water.............................................................. 5.9.2 Distribution and Concentrations of Point Sources of Groundwater Constituents ................. 5.9.3 Distribution and Concentrations of Diffuse or Natural Groundwater Constituents ............... 5.9.3.1 Total Dissolved Solids...................................................................................................... 5.9.3.2 Nitrate............................................................................................................................. 5.9.3.3 Arsenic............................................................................................................................. 5.9.3.4 Boron............................................................................................................................... 5.9.3.5 Other Constituents.......................................................................................................... iv Page 310 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 6 Water Budget (§ 354.18)....................................................................................................................... 6.1 Climate............................................................................................................................................ 6.1.1 Historical Climate/Base Period............................................................................................. 6.2 Water Budget Data Sources.......................................................................................................... 6.3 Historical Water Budget................................................................................................................ 6.3.1 Historical Time Period........................................................................................................... 6.3.2 Historical Land Use............................................................................................................... 6.3.3 Historical Surface Water Budget.......................................................................................... 6.3.4 Historical Groundwater Budget........................................................................................... 6.3.5 Total Groundwater in Storage............................................................................................. 6.3.6 Change in Storage................................................................................................................ 6.3.7 Sustainable Yield.................................................................................................................. 6.3.8 Quantification of Overdraft (Historical)............................................................................... 6.4 Current Water Budget.................................................................................................................. 6.5 Projected Water Budget.............................................................................................................. 6.5.1 Assumptions......................................................................................................................... 6.5.2 Inflows................................................................................................................................... 6.5.3 Outflows............................................................................................................................... 6.5.4 Change In Storage................................................................................................................ 6.5 Projected Water Budget................................................................................................................. 6.5.1 Assumptions............................................................................................................................ 6.5.2 Inflows..................................................................................................................................... 6.5.3 Outflows.................................................................................................................................. 6.5.4 Change In Storage................................................................................................................... 7 Monitoring Networks (§ 354.32 and § 354.34)................................................................................... 7.1 Monitoring Objectives................................................................................................................. 7.1.1 Management Areas............................................................................................................. 7.1.2 Representative Monitoring Site ......................................................................................... 7.1.3 Scientific Rationale............................................................................................................... 7.1.4 Existing Monitoring Programs.............................................................................................. 7.2 MONITORING NETWORKS........................................................................................................... 7.2.1 Groundwater Level Monitoring Network............................................................................ 7.2.2 Groundwater Quality Monitoring Network......................................................................... 7.2.3 Surface Water Flow Monitoring Network............................................................................ v Page 311 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO 7.3 Sustainability Indicator Monitoring............................................................................................ 7.3.1 Chronic Lowering of Groundwater Levels............................................................................ 7.3.2 Reduction of Groundwater Storage..................................................................................... 7.3.3 Seawater Intrusion............................................................................................................... 7.3.4 Degraded Groundwater Quality........................................................................................... 7.3.5 Land Subsidence................................................................................................................... 7.3.6 Depletion of Interconnected Surface Water....................................................................... 7.4 Monitoring Technical and Reporting Standards......................................................................... 7.4.1 Groundwater Levels........................................................................................................... 7.4.2 Groundwater Quality.......................................................................................................... 7.4.3 Surface Water Flow............................................................................................................. 7.4.4 Monitoring Frequency........................................................................................................ 7.5 Data Management System.......................................................................................................... 7.6 Assessment and Improvement of Monitoring Network.............................................................. 7.7 Annual Reports and Periodic Evaluation by the GSAS......................................................................... 8.0 Sustainable Management Criteria (§ 354.22-30)................................................................................... 8.1 Sustainability Goal........................................................................................................................... 8.2 Process for Establishing Sustainable Management Criteria........................................................... 8.2.1 Minimum Thresholds.............................................................................................................. 8.2.2 Measurable Objectives........................................................................................................... 8.2.3 Undesirable Results................................................................................................................. 8.3 Chronic Lowering of Groundwater Levels Sustainability Indicator ................................................. 8.3.1 Locally Defined Undesirable Results....................................................................................... 8.3.2 Minimum Thresholds and Measurable Objectives................................................................. 8.3.3 Relation to Other Sustainability Indicators............................................................................. 8.4 Change in Storage Sustainability Indicator..................................................................................... 8.4.1 Locally Defined Undesirable Results....................................................................................... 8.4.2 Minimum Thresholds.............................................................................................................. 8.4.3 Measurable Objectives........................................................................................................... 8.4.4 Relation to Other Sustainability Indicators............................................................................. 8.5 Seawater Intrusion Sustainability Indicator.................................................................................... 8.5.1 Locally Defined Undesirable Results....................................................................................... 8.5.2 Minimum Thresholds.............................................................................................................. 8.5.3 Measurable Objectives........................................................................................................... 8.5.4 Relation to Other Sustainability Indicators............................................................................. vi Page 312 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 8.6 Degraded Water Quality Sustainability Indicator........................................................................... 8.6.1 Locally Defined Undesirable Results....................................................................................... 8.6.2 Minimum Thresholds.............................................................................................................. 8.6.3 Measurable Objectives........................................................................................................... 8.6.4 Relation to Other Sustainability Indicators............................................................................. 8.7 Subsidence Sustainability Indicator................................................................................................ 8.7.1 Locally Defined Undesirable Results....................................................................................... 8.7.2 Minimum Thresholds.............................................................................................................. 8.7.3 Measurable Objectives........................................................................................................... 8.7.4 Relation to Other Sustainability Indicators............................................................................. 8.8 Depletion of Interconnected Surface Water Sustainability Indicator ............................................. 8.8.1 Locally Defined Undesirable Results....................................................................................... 8.8.2 Minimum Thresholds.............................................................................................................. 8.8.3 Measurable Objectives........................................................................................................... 8.8.4 Relation to Other Sustainability Indicators............................................................................. 8.9 Management Areas......................................................................................................................... 8.9.1 Minimum Thresholds and Measurable Objectives................................................................. 8.9.2 Monitoring and Analysis......................................................................................................... 8.9.3 Explanation of How Operation of Management Area Will Avoid Undesirable Results.......... 9 Projects and Management Actions (§ 354.44)....................................................................................... 9.1 Projects........................................................................................................................................... 9.1.1 Project A.................................................................................................................................. 9.2 Management Actions...................................................................................................................... 9.2.1 Management Action A............................................................................................................ 9.3 Projects Needed to Mitigate Overdraft.......................................................................................... 10 Implementation Plan.............................................................................................................................. 10.1 Cost of Implementation.................................................................................................................. 10.2 Funding Alternatives....................................................................................................................... 10.3 Implementation Schedule............................................................................................................... 10.4 GSP Annual Reporting..................................................................................................................... 10.5 Periodic Evaluations of GSP............................................................................................................ 11 Notice and Communications (§ 354.10)................................................................................................. 11.1 Communications and Engagement Plan......................................................................................... 11.2 Nature of Consultations.................................................................................................................. 11.3 Public Meetings............................................................................................................................... vii Page 313 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 11.4 Incorporation of Feedback in Decision -Making Process................................................................. 11.5 Comments Received....................................................................................................................... 11.6 Responses to Comments................................................................................................................. 12 Interagency Agreements (§ 357.2-4)..................................................................................................... 12.1 Coordination Agreements............................................................................................................... 13 References.............................................................................................................................................. 14 Appendices............................................................................................................................................. The grey highlighted sections in the Table of Contents (TOC) indicate that the section has been previously released (Chapters 1 through 6) or will be released in the future (Chapters 8 through 14). The complete list of the anticipated TOC is presented to give the reader context as to how Chapter 7- Monitoring Network, connects with the complete Groundwater Sustainability Plan. viii Page 314 of 1183 SLO Basin Groundwater Sustainability Plan List of Figures County of SLO and City of SLO LIST OF FIGURES Figure 7-1: Water Level Monitoring Network Figure 7-2: Water Quality Monitoring Network Figure 7-3: Surface Water Flow Monitoring Network ix Page 315 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO TABLES Table 7-1: Groundwater Level Monitoring Network Table 7-2: Recommended Groundwater Level Monitoring Additions Table 7-3 Groundwater Quality Monitoring Network Table 7-4 Existing Surface Water Flow Monitoring Network Table 7-5 Recommended Surface Water Flow Monitoring Network Additions Table 7-6 Interconnected Surface Water and Associated GDE indicator Monitoring Locations Tables x Page 316 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES Appendices Appendix 7A Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin Appendix 7B Groundwater Level Measurement Procedures for the San Luis Obispo Valley Groundwater Basin GSP Appendix 7C Streamflow Measurement in Natural Channels Appendix 7D Data Management Plan Xi Page 317 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin BMP Best Management Practices (DWR) Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GDE Groundwater Dependent Ecosystem GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan ILRP Irrigated Lands Regulatory Program kWh Kilowatt -Hour LUCE Land Use and Circulation Element xii Page 318 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCR Well Completion Report WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant xiii Page 319 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 320 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7 MONITORING NETWORKS (§ 354.32 AND § 354.34) This chapter describes the proposed monitoring networks for the GSP in accordance with SGMA regulations in Subarticle 4: Monitoring Networks. Monitoring is a fundamental component of the GSP necessary to identify impacts to beneficial uses or Basin users, and to measure progress toward the achievement of any management goal. The monitoring networks must be capable of capturing data on a sufficient temporal and spatial distribution to demonstrate short-term, seasonal, and long-term trends in groundwater and related surface water conditions, and to yield representative information about groundwater conditions for GSP implementation. There are three monitoring networks for the Basin: a groundwater level network, a groundwater quality network, and a surface water flow network. Chapter 7 describes the monitoring objectives, rationale, protocols, and data reporting requirements of the monitoring networks. Monitoring requirements for sustainability indicators are presented, and data gaps are identified, along with steps to be taken to fill the data gaps before the first five-year assessment. The following is a list of applicable SGMA sustainability indicators that will be monitored in the Basin: • Chronic lowering of groundwater levels. • Reduction in groundwater storage. • Degradation of groundwater quality. • Land subsidence. • Depletion of interconnected surface water (includes GDE sustainability). Sustainability indicators are discussed in detail in Chapter 8. This monitoring networks chapter focuses on the monitoring sites and data collection needed to support the evaluation of each sustainability indicator. 7.1 MONITORING OBJECTIVES The proposed monitoring network must be able to adequately measure changes in groundwater conditions to accomplish the following monitoring objectives: • Demonstrate progress toward achieving measurable objectives. • Monitor impacts to the beneficial uses and users of groundwater. • Monitor changes in groundwater conditions relative to measurable objectives and minimum thresholds for sustainability indicators. • Quantify annual changes in water budget components. The monitoring network must provide adequate spatial resolution to properly monitor changes to groundwater and surface water conditions relative to measurable objectives and sustainability indicators within the Basin. The network must also provide data with sufficient temporal resolution to demonstrate short-term, seasonal and long-term trends in groundwater and related surface conditions. 7.1.1 Management Areas Although there are differences in land use and associated water budgets between the San Luis Valley and Edna Valley subareas, as described in Chapter 6, separate management areas have not been formally established. The monitoring network includes representative wells across the Basin for which minimum thresholds and measurable objective have been selected based on local conditions, as described in Chapter 2 Page 321 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7.1.2 Representative Monitoring Sites Monitoring sites are the individual locations within a monitoring network and consist of groundwater wells and stream gages. While a monitoring network uses a sufficient number of sites to observe the overall groundwater conditions and the effects of Basin management projects, a subset of the monitoring sites may be used as representative for meeting the monitoring objectives for specific sustainability criteria. Representative monitoring sites are the locations at which sustainability indicators are monitored, and for which quantitative values for minimum thresholds, measurable objectives, and interim milestones are defined. The criteria that were used to determine which wells to utilize are as follows: • A minimum 10-year period of record of historical measurements spanning wet and dry periods. • Available well information (well depth, screened interval). • Access considerations. • Proximity and frequency of nearby pumping wells. • Spatial distribution relative to the applicable sustainability indicators. • Groundwater use. • Impacts on beneficial uses and Basin users. 7.1.3 Scientific Rationale GSP monitoring program development is based on a combination of SGMA monitoring networks best management practices (BMPs), local hydrogeology, and the monitoring requirements for individual sustainability criteria. Some of the SGMA monitoring network BMPs implemented for this GSP include the following: • Defining the monitoring objectives. • Utilizing existing monitoring networks and data sources to the greatest extent possible to meet those objectives. • Adjusting the temporal/spatial coverage to provide monitoring data consistent with the need. • Efficient use of representative monitoring sites to provide data for more than one sustainability indicator. County monitoring programs that existed before SGMA include sites that do not meet SGMA monitoring network BMPs with respect to known construction information, such as wells with no available Well Construction Report (WCR) and active wells that are used for groundwater supply. While not prohibiting the use of these wells as a monitoring site, SGMA regulations require that the GSP identify sites that do not meet BMPs and describe the nature of the divergence. If the monitoring network uses wells that lack construction information, the GSP shall include a schedule for acquiring monitoring wells with the necessary information or shall demonstrate that such information is not necessary to understand or manage groundwater in the Basin. As discussed in Chapters 4 and 5, information from available boring logs indicates that there is no regional or laterally extensive aquitard separating the Alluvial aquifer, Paso Robles Formation aquifer, and Pismo Formation aquifer in the Basin. In the San Luis Valley, a physical distinction between Alluvium and Paso Robles Formation sediments is often not apparent, and information from WCRs indicates that wells are regularly screened across productive strata in both formations, which effectively function as a single hydrogeologic unit. DWR (1997) also concluded that there are no continuous confining layers, and unconfined groundwater table conditions essentially prevail throughout the Basin, including the Edna Valley. A minor exception is recognized in Chapter 6 (Section 6.3.5) near the intersection of Biddle Ranch Road and Edna Road, where there is a shallow (semi -perched) alluvial aquifer tapped by a former windmill well. Therefore, with respect to groundwater level monitoring, data collected from wells completed in one or more of the three principal aquifers (Alluvium, Paso Robles Formation, and Pismo Formation) can be used collectively for groundwater elevation contouring and storage estimates. Obtaining well construction Page 322 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO information for all monitoring network wells is not an immediate necessity and will be addressed (see Section 7.6). 7.1.4 Existing Monitoring Programs Existing monitoring programs are discussed in Chapter 3. Figure 3-9 (Chapter 3) shows the locations of monitoring wells identified in the GAMA program (publicly available groundwater quality data), the SLOFCWCD semi-annual groundwater level program, and the CCRWQCB Irrigated Lands Regulatory Program (groundwater quality data). There are also groundwater level and quality data collected for various contaminant investigations and monitoring programs that are publicly available from the SWRCB Geotracker website. 7.2 MONITORING NETWORKS This section introduces the proposed GSP monitoring networks and describes the networks in relation to the following SGMA sustainability indicators applicable to the Basin: • Chronic lowering of groundwater levels. • Reduction of groundwater in storage. • Groundwater quality degradation. • Land subsidence. • Depletion of interconnected surface water (includes GDE sustainability). The GSP monitoring program consists of three separate networks, one for groundwater levels, one for groundwater quality, and one for surface water flow. Each network is described below. 7.2.1 Groundwater Level Monitoring Network Groundwater level monitoring is a fundamental tool in characterizing Basin hydrology. Groundwater levels (often reported as elevations relative to a reference point) in wells are measures of the hydraulic head in an aquifer. Groundwater moves in the direction of decreasing head (downgradient), and groundwater elevation contours can be used to show the general direction and hydraulic gradient associated with groundwater movement. Changes in the amount of groundwater in storage within an aquifer can also be estimated based on changes in hydraulic head, along with other parameters. There are 40 monitoring wells in the GSP groundwater level monitoring network, 22 wells in the San Luis Valley and 18 wells in the Edna Valley (Figure 7.1 and Table 7-1). Construction information is available for 31 of the 40 wells. Based on the available information, 16 of the wells are interpreted to be alluvial wells, while the remaining 24 wells tap into the Paso Robles Formation, Pismo Formation, or are mixed aquifer wells that utilize groundwater from more than one aquifer. Half the wells are used for irrigation, seven are private domestic wells, and 13 are dedicated monitoring wells. Groundwater levels may be used as a proxy for monitoring other sustainability indicators (besides chronic lowering of water levels) provided that significant correlation exists between groundwater elevations and the sustainability indicator for which the groundwater elevations serve as a proxy. Ten of the groundwater level monitoring network wells are representative monitoring site wells used for evaluating sustainability criteria. Six representative monitoring site wells are used for evaluating chronic lowering of groundwater level and reduction of groundwater in storage, which is correlated with groundwater levels (Chapter 6, Section 6.3.5). Two wells are used for evaluating subsidence, which is correlated with groundwater levels C Page 323 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO in the area being monitored (Chapter 4, Section 4.7), and three wells are used to evaluate depletion of interconnected surface water, which is correlated with groundwater levels (Chapter 5, Section 5.7). One of the wells used to evaluate depletion of interconnected surface water is also a representative monitoring site for subsidence. The sustainability criteria and associated minimum thresholds and measurable objectives are presented in Chapter 8. 7.2.1.1 Groundwater Level Monitoring Data Gaps SGMA regulations do not require a specific density of monitoring wells, other than being sufficient to represent groundwater conditions for GSP Implementation. The monitoring network well density is roughly 20 wells per 10 square miles, which is 10 times greater density than guidelines for the statewide CASGEM program. There are currently sufficient wells in the network to provide information for overall sustainable management of the Basin, although some local data gaps have been identified that will be addressed during GSP implementation. A groundwater level monitoring well is recommended in the Foothill Boulevard/O'Conner Way area to improve groundwater level contour control and associated groundwater storage estimates in the Los Osos Valley within the Basin. Other groundwater level monitoring locations are recommended for GDE indicator evaluation and are in the vicinity of existing or proposed stream gage locations. The background and rationale for the GDE indicator monitoring sites are presented in a separate technical memorandum (Appendix 7A). Table 7-1 presents the GSP groundwater level monitoring network wells. Table 7-2 presents additional areas recommended for groundwater level monitoring. Figure 7-1 shows the location of the existing groundwater level monitoring wells and the recommended additional monitoring areas. 5 Page 324 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO Table 7-1 Groundwater Level Monitoring Network 1 Local ID 2 TRS / State ID Well Depth (feet) Screen Interval (feet) RP Elev.' (feet AMSL) First Data Year Last Data Year Data period (years) Data Count Aquifer' Well Criteria' Well Use' GSA SLV-01 30S/12E-23E (pending) (pending) 304 (pending) Qa GDE, T MW County SLV-02 30S/12E-22G (pending) (pending) 276 (pending) Qa MW City SLV-03 30S/12E-30P 153 Qa IRR-1 County SLV-04 30S/12E-35B1 48 28-48 215.6 1991 2020 29 38 Qa IRR-A City SLV-05 30S/12E-35D 52 32-52 187 1990 2018 28 7 Qa GDE, T IRR-A City SLV-06 31S/12E-04D 85 45-85 150 1989 1 1 Qa T MW City SLV-07 31S/12E-04K 125 55-125 139.5 1992 2000 8 46 Qpr PS-1 City SLV-08 31S/12E-03K 70 50-70 128 1988 2020 32 2 Qpr IRR-A City SLV-09 31S/12E-4R1 130 40-130 129.5 1988 2020 32 48 Qa/Qpr SUB PS-1 City SLV-10 31S/12E-3Q 48 131 2017 2020 3 82 Qa MW City SLV-11 31S/12E-3P1 61 119 1990 2006 16 31 Qa MW City SLV-12 31S/12E-10D3 175 50-90; 150-170 109.2 1992 2020 28 72 Qa/Qpr/Tps ISW, SUB, T IRR-A City SLV-13 31S/12E-11D 40 5-40 121.75 1996 2020 24 49 Qa T, GDE MW City SLV-14 31S/12E-12E 20 5-20 144.68 1990 2020 30 60 Qa MW County SLV-15 31S/12E-10G2 190 122 1965 2020 55 90 Qpr IRR-A City SLV-16 31S/12E-10H3 165 65-165 122 1984 2020 36 68 Qpr WL DOM-A City SLV-17 31S/12E-11M 100 60-100 119.78 1996 2020 24 73 Qpr MW County SLV-18 31S/12E-11K 30 6-21 133.28 1990 2020 30 59 Qa MW County SLV-19 31S/12E-14C1 128 1958 2020 62 98 Qpr WL, GDE, T IRR-A County SLV-20 31S/13E-18D 202 Qa MW County SLV-21 31S/12E-13A 60 50-60 178.68 2018 2018 1 Qpr MW County SLV-22 31S/12E-13C 100 11-100 178 2004 2020 16 2 Qpr/Kjf T IRR-I County EV-01 31S/13E-16N1 72 324 1958 2020 62 99 Qa ISW, T DOM-A County EV-02 31S/13E-20A 75 305 Qa GDE IRR-I County EV-03 31S/13E-19H4 250 178-250 254 Qpr/Tps IRR-A County EV-04 31S/13E-19H1 262 1958 2020 62 100 Tps WL, GWS, T IRR-A County EV-05 31S/13E-20G 400 120-400 280 Tps IRR-1 County EV-06 31S/13E-19J1 251 1998 2020 22 44 Qpr DOW County EV-07 31S/13E-19J2 250 1998 1 2020 22 45 1 Tps DOM-A County EV-08 31S/13E-21L 350 Qa GDE, T IRR-A County EV-09 31S/13E-19R3 440 130-190; 290-430 239 1974 2020 46 45 Tps/Tm WL, GWS PS -A County EV-10 31S/13E-28F 340 200-330 344 Qpr/Tps IRR-A County EV-11 31S/13E-20F6 150 55-150 230 2011 2020 9 Qpr/Tm ISW, GDE, T MW County EV-12 31S/13E-28J3 600 303 1993 2020 27 39 Qpr/Tps IRR-A County EV-13 31S/13E-27M3 400 130-380 289 1993 2020 27 34 Qpr/Tps WL, GWS IRR-A County EV-14 31S/13E-27R 300 90-290 319 2017 2020 3 6 Qpr/Tps T MW County EV-15 31S/13E-27Q 307 1989 2020 31 9 Qpr/Tps DOW County EV-16 31S/13E-35D 260 200-260 323 1988 2020 32 188 Tps WL, GWS PS -A County EV-17 31S/13E-35F 260 200-260 333 2014 2020 6 66 Tps/Kjf PS-1 County EV-18 31S/13E-36R1 327 1968 2020 52 99 (out of Basin) IRR-A County Notes: 1- Representative Monitoring Sites are in bold. Wells with known State Well Completion Reports are underlined. 2- TRS = Township Range Section and %-% section listed, State Well ID bolded where applicable. 3- Reference Point elevations from various sources with variable accuracy. 4- Principal Aquifers are Quaternary Alluvium (Qa), Quaternary Paso Robles Formation (Qpr), and Tertiary Pismo Formation (Tps). Other bedrock aquifers (non -Basin sediments) are Tertiary Monterey Formation (Tm) and Cretaceous -Jurassic Franciscan Assemblage (KJf). Aquifers are inferred where construction information is not available. 5- Representative well criteria include Subsidence (SUB), Interconnected Surface Water Depletion (ISW), Chronic Water Level Decline (WL), and Groundwater Storage Decline (GSW). Other criteria are Transducer site (T), and Groundwater Dependent Ecosystem indicator evaluation site (GDE), which may be paired with nearby existing or proposed stream gage. Transducer installations are pending well owner authorization. Measurement frequency is semi-annual for all wells except Transducer sites (T), which are measured daily. 6- Well Use includes Monitoring Well (MW), Irrigation Well (IRR), Public Supply Well (PS), and Domestic Well (DOM). Modifiers are Active (A) or Inactive (I). Information for some wells inferred pending confirmation. Page 325 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO ♦` CV-03 mn� Monitoring Networks (§ 354.32 and § 354.34) i � m !( SLV-01 - 1 Ir �<, SLV-02ra !, SLV 05 SLV-04 i /-07 y `,SLV 10 LV �!V 08Nil LV;09 SLV,12 SLV-11 i �= I SLV-13 y'SLV 14 . — S LV-16Z.y n � SLO15 SLV-17 SLV-18�1'' _.__ 1 i SLV-19 ----- -- SLV-21 SLV-20 ,SLV-22 f E V-01 �►� EV-03 EV-04 EV-02/ EV-06 I : 0 EV-05 EV-08EV-I '� �EV 09� _ EV 11 EV-10 ~� { Prepared For: N` Au[hor. TK - Date 1v19/2o20 0 0-25 0.5 0.75 1 rte 0 0� SAN LUIS OBISPO VALLEY BASIN GSP Onol EV-12 ' EV-13` E Explanation rSLO Valley Groundwater Basin Boundary --- Subarea Boundary City Limits Existing Well Site Q Existing Well Site - Transducer Recommended Recommended Additional Well Site Representative Well by Criteria Measured Chronic Water Level Decline Storage Decline Land Subsidence Interconnected Surface Water Depletion V-15 EV-14_ EV-16 1 i EV-17 rEV-18 References: Notes: a Figure 7-1 1. Coordinate System'. State Plane California VFIPS O405 Feet 1Water er Level Monitoring Network 2. Projection'. Lambert Conformal Conic 2. 7 3. Firozortal Datum. NAD 83 3. 4. Vertical Datum. NAVD 88 5. Basemap'. USGS 7S' Topographic Map 7 Page 326 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO Table 7-2 Recommended Groundwater Level Monitoring Network Additions Water Level Data Gap ID Location Purpose WL-A Near Foothill Blvd. and O'Connor Way Groundwater elevation contours and storage WL-B Madonna Road near Laguna Lake GDE indicator evaluation WL-C Elks Lane south of SLO Creek Bridge GDE indicator evaluation WL-D South Higuera near old Highway Bridge GDE indicator evaluation WL-E Davenport Creek east of Crestmont Road GDE indicator evaluation, groundwater elevation contours and storage WL-F Corbett Canyon Road near Canada Verde GDE indicator evaluation 7.2.2 Groundwater Quality Monitoring Network Groundwater quality monitoring refers to the periodic collection and chemical or physical analysis of groundwater from wells. As discussed in Chapter 5 (Section 5.9), the quality of groundwater in the Basin is generally good. Groundwater quality trends in the Basin are stable, with no significant trends of ongoing deterioration of groundwater quality based on the Central Coast Basin Plan. Groundwater quality networks should be designed to demonstrate that the degraded groundwater quality sustainability indicator is being observed for the purposes of meeting the sustainability goal (DWR Monitoring Networks BMP, 2016). In other words, the main purpose of the groundwater quality monitoring network is to support the determination of whether the degradation of groundwater quality is occurring at the monitoring sites, based on the sustainability indicator constituents and minimum thresholds selected. This GSP groundwater quality network is also designed to use existing monitoring programs to the greatest degree possible (DWR Monitoring Networks BMP, 2016). Sustainability indicator constituents selected for groundwater quality are Total Dissolved Solids (TDS), Nitrate, and Arsenic. These constituents were introduced in Chapter 5 (Section 5.9.3) as diffuse or naturally occurring in the Basin and are further discussed in relation to sustainability indicators in Section 7.3.4 and in Chapter 8. Two other water quality constituents associated with notable contaminant plumes in the South San Luis Obispo and Buckley Road areas (Figure 7-2 and Section 7.3.4) will also be monitored within the GSP water quality network, but not as sustainability indicators. The groundwater quality network consists of nine sites (Figure 7-2), which are all are Public Water System supply wells. Water quality for these wells can be accessed using the GAMA Groundwater Information System. Wells in the Irrigated Lands Regulatory Program were evaluated for potential inclusion in the GSP monitoring program, however, the irrigation wells have not historically been sampled for groundwater quality at regular intervals, therefore no historical record of groundwater quality data exists. In addition, Agricultural Order 4.0 of the Irrigated Lands Regulatory Program is currently in draft form and under review. Selection of specific wells regulated under that program would not be recommended until the program is implemented and monitoring data is available for review. By comparison, the public water system wells have a history of groundwater quality data and specific wells are sampled at regular intervals for the three indicators recommended for groundwater quality monitoring in Chapter 8 — TDS, Nitrate, and Arsenic. Ri Page 327 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7.2.2.1 Groundwater Quality Monitoring Data Gaps Current groundwater quality monitoring within the Basin is sufficient to collect the spatial and historical data needed to determine groundwater quality trends for groundwater quality indicators. The GAMA database includes 120 wells within the Basin boundaries that have been monitored for groundwater quality in the last three years. The nine wells selected (Figure 7-2) provide representative Basin coverage but can be supplemented with other data if needed to support sustainability indicator evaluation. The water quality network wells will be used collectively to provide the metric for use with the groundwater quality degradation sustainability indicator (Chapter 8). No data gaps in groundwater quality monitoring are currently identified. Table 7-3 presents the GSP groundwater quality monitoring network. Figures 7-2 show the locations of the groundwater quality monitoring wells. Table 7-3 Groundwater Quality Monitoring Network Local ID State ID1 First Data Year Last Data Year Data period (years) Data Count (TDS)z Data Count (N)3 Data Count (As )4 GSA WQ-1 4000206-003 2003 2019 16 4 12 5 County WQ-2 4000780-001 2002 2019 17 5 21 6 City WQ-3 4010009-004 1989 2019 30 8 42 8 City WQ-4 4000604-001 2002 2020 18 6 69 6 City WQ-55 4000734-001 2004 2020 16 4 21 6 County WQ-6 4000819-001 2017 2020 3 3 4 1 City WQ-7 4010023-008 1992 2020 28 19 142 148 County WQ-8 4000202-001 2003 2018 15 5 23 27 County WQ-9 4000765-001 2002 2019 17 7 19 36 County Notes: Data accessed on GAMA Groundwater Information System 1- State ID for public water system 2- TDS = Total Dissolved Solids — typically measured every three years 3- N = Nitrate -Nitrogen —typically measured every year or quarterly 4- As = Arsenic — variable from monthly to every three years 5- WQ-5 also used to track TCE (see Section 8.2.4) 0 Page 328 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Monitoring Networks (§ 354.32 and § 354.34) a--------- Explanation /� _ _, I� ♦f `�r', r� SLO Valley Groundwater i '� �� ��•.�i „ Basin Boundary 7 Subarea Boundary - ,e_ - City Limits j : �� �� �''' Ile.` Q Existing Well Site �- Plume Area ` �, 1. \ •`���� �\ - a. WQ-2 South SLO WQ. `PCE area \,\ 1 r; WQ4 - ,V .r` i �•\ i Buckley Road /. TCE area ♦♦ �WQ-s; rf A WQ ♦` Q ♦♦ W Q-8 > r , r f x OWQ 9 ; 5 ., 4a 0 Ile 47 t �� ♦� Prepared For: N Authorr TK i Date11/24202n 0 0.25 0.5 0.75 1 0 0� SAN LUIS OBISPO VALLEY BASIN GSP m References: Notes: 1-Coordinate System: State Plane Calif mid V HIPS O405 Feet 1. 2- Projection' Lambert Conformal Conic 2. 3. Hirozontal Datum: NAD 83 3. 4. Vertical Datum: NAVD 88 5- Basemap: USGS 75' Topographic Map I t Figure 7-2 Water Quality Monitoring Network 10 Page 329 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7.2.3 Surface Water Flow Monitoring Network Surface water flow monitoring can provide valuable information for the Basin model and for evaluating potential depletion of interconnected surface water for groundwater dependent ecosystems (GDEs), which is one of the sustainability indicators. The evaluation of surface water connectivity with the Basin and relevance to GDEs is described in a technical memorandum (Appendix 7A) that includes recommendations for the surface water flow monitoring sites identified in this chapter. As summarized in Chapter 3, there are six permanent stream gages in or adjacent to the Basin, all within the San Luis Valley subarea watershed (Figure 7-3). The existing gaging stations only provide stage data, and not actual stream flow data. Stream stage is the height of water level in the stream above an arbitrary point, usually at or below the stream bed. Stage data can be useful for identifying flow and no -flow conditions, flood stage alerts, and analyzing the timing of precipitation and runoff in watersheds. Streamflow data is critical for quantifying Basin recharge from stream seepage as part of the water budget/model and for addressing sustainability indicators related to GDEs and depletion of interconnected surface water. Stage data can be converted to streamflow through the use of a rating curve, which incorporates information that is specific to each site, including the cross -sectional area of the channel and the average surface water velocity for a given flow stage. A description of the methodology for monitoring surface water flow in natural channels is presented in Appendix 7B. There are partial rating curve approximations for three of the sites based on actual streamflow measurements (Section 3.6.1.3). A modeling approach to estimating rating curves was performed by Questa Engineering (2007), but the results of that study have not been validated with field measurements. 7.2.3.1 Surface Flow Monitoring Data Gaps The existing gages are all in the San Luis Valley subarea watershed, where the majority of potential GDEs have been identified (Figure 5-15; Chapter 5). There are no surface flow monitoring sites in the Edna Valley subarea, which is the subarea subject to overdraft (Chapter 6). Data gaps for surface water flow monitoring with respect to interconnected surface water depletion, GDEs, and the water budget are identified on Stenner Creek near the upstream Basin boundary, on San Luis Obispo Creek near the downstream Basin boundary, and on Pismo Creek near the downstream Basin boundary (Appendix 7A). Three stream gages are recommended for installation to fill these data gaps adjacent to the Basin boundaries. In addition, two more stream gage sites are recommended on East Corral de Piedra Creek and West Corral de Piedra Creek at Orcutt Road to fill a data gap in the water budget in the Edna Valley. Stream gages on these two principal drainages, along with a gage downstream of their confluence on Pismo Creek, will provide important information on stream seepage in the Edan Valley for the water budget/Basin model, and will allow a direct comparison of streamflow between the two watersheds, one of which has a permitted reservoir upstream of Orcutt Road (Chapter 6, Section 6.3.3.1). Rating curve development is recommended for all stream gages to provide the stream flow information needed for the water budget/model and sustainability indicator evaluation. Table 7-4 presents the GSP surface water flow monitoring network. Table 7-5 presents recommended sites for additional stream gages. Figure 7-3 shows the locations of the existing gages, recommended gages, and the nearby groundwater level monitoring sites (both existing and recommended) that can be used to evaluate interconnected surface water depletion and GDE indicators (see Section 7.3.6 and Appendix 7A). 11 Page 330 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO Table 7-4 Existing Surface Water Flow Monitoring Network Local ID Water Course Location First Data Year Data Interval Data period (years) GSA SG-745 San Luis Obispo Creek Andrews St. Bride 2006 15-minutes 14 City SG-781 Stenner Creek Nipomo Street 2005 15-minutes 15 City SG-790 San Luis Obispo Creek Marsh Street 2019 15-minutes 1 City SG-740 I San Luis Obispo Creek Elks Lane 2005 15-minutes 15 City SG-778 Prefumo Creek Madonna Road 2005 15-minutes 15 Cit SG-783 East Fork Creek Jesperson Road 2005 15-minutes 15 County Table 7-5 Recommended Surface Water Monitoring Network Additions Surface Water Flow Gap ID Location Purpose Water Budget, Surface water connectivity, SG -A Stenner Creek at Stenner Creek Road GDE indicator evaluation San Luis Obispo Creek at Old Highway Water Budget, Surface water connectivity, SG-B Bridge GDE indicator evaluation West Corral de Piedra Creek at Orcutt SG-C Water Budget Road SG-D East Corral de Piedra Creek at Orcutt Road Water Budget Water Budget, Surface water connectivity, SG-E Pismo Creek at Railroad Crossing GDE indicator evaluation 12 Page 331 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Monitoring Networks (§ 354.32 and § 354.34) ---------- SLV-01 �krr ' l iIs 11 f SLV=5 Shallow Bedrock SG-740 y ,SG-778 �*N1 \ Greek re S 13 \ LV- `- 2� " SLV-1 r Sir =r� : if. SLV-19 - o F SSG-783LjavO ..i C Prepared For: N IN Au[hor'. TK I{,y Date 1V3012020 0 0.25 05 0,75 1 m 1 k MEl 0 0� SAN LUIS OBISPO VALLEY BASIN GSP References: 1. Coordinate SystemState Plane Califomia V DIPS O405 Feet 2. Projection: Lambert Conformal Conic 3. Hirozental Datum. DAD 83 4. Vertical Datum. DAVD 88 5. Basemap- USGS 7 5' Topographic Map Explanation r-, SLO Valley Groundwater Basin Boundary --- Subarea Boundary ; City Limits Q Existing Stream Gage Site Q Recommended Additional Stream Gage Site Water Level Monitoring Site for Interconnected Surface Water and GDE Indicator Evaluation Existing Well Recommended Additional Site REV-08 1 EV-11 7t {i A .L fi V• U 0 5 Notes: Figure 7-3 z Surface Water Flow Monitoring Network 3 13 Page 332 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7.3 SUSTAINABILITY INDICATOR MONITORING Sustainability indicators are the effects caused by groundwater conditions occurring throughout the Basin that, when significant and unreasonable, become undesirable results. The SGMA sustainability indicators for GSP implementation are as follows: • Chronic lowering of groundwater levels. • Reduction in groundwater storage. • Seawater Intrusion (this indicator is not applicable to Basin). • Degraded groundwater quality. • Land subsidence. • Depletion of interconnected surface water (includes GDE Sustainability). 7.3.1 Chronic Lowering of Groundwater Levels Chronic lowering of groundwater levels can lead to a significant and unreasonable depletion of the water supply. All of the groundwater level monitoring network wells can be used for evaluating chronic lowering of groundwater levels, with a selected subset of six representative wells formally assigned to assess Minimum Thresholds and Measurable Objectives (Chapter 8). Groundwater monitoring network wells not included in the subset of representative wells are included in the network primarily for preparing groundwater level contour maps, which are used for evaluating hydraulic gradient and groundwater flow direction. Groundwater level contour maps can reveal groundwater pumping depressions that result from lowering of groundwater levels and can also be used to calculate change in groundwater storage. The area where chronic lowering of water levels has been occurring is in the Edna Valley (Chapter 5; Figure 5-11). Four of the six representative wells focus on this area (Figure 7-1). Static groundwater level measurements shall be collected at least two times per year, to represent seasonal low and seasonal high groundwater conditions. Historically, the semi-annual groundwater level program conducted by SLOFCWCD has measured groundwater levels in April and October of each year. This schedule will be maintained for the GSP. In addition, 12 wells have been recommended (based on spatial distribution, equipment access, and interconnected surface water/GDE applications; Figure 7-1) for pressure transducer installation to automatically record groundwater levels on a daily basis, providing more detailed information on short- term trends, seasonal high and low conditions, and on potential GDEs and interconnected surface water depletion. Pressure transducers are instruments that record water levels automatically at pre -determined intervals. They are installed below the water surface in a well and use the pressure of the overlying water column to produce a depth to water measurement. Pressure transducers are a very efficient means of collecting groundwater level data at frequent intervals. The recommended transducer locations are listed in Table 7-1. 7.3.2 Reduction of Groundwater Storage Groundwater storage and water levels are directly correlated, and chronic lowering of water levels also leads to a reduction of groundwater storage. Change in groundwater storage will be monitored using the overall monitoring network, while selected representative wells will track reduction of groundwater storage as the sustainability indicator. The comprehensive 40-well monitoring network will be used to contour groundwater elevations for seasonal high conditions, from which annual spring groundwater storage estimates will be estimated and the annual change in storage reported as required for Annual Reports. Groundwater storage will be 14 Page 333 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO calculated using the specific yield method, which is the product of total saturated Basin volume and average specific yield. The saturated Basin volume is the volume between a groundwater elevation contour map for a specific period (such as Spring 2019) and the base of permeable sediments (Chapter 6; Section 6.3.5). Representative wells that will be used for monitoring reductions in groundwater storage are listed in Table 7-1 and shown in Figure 7-1. Chapter 8 discusses the Minimum Thresholds and Measurable Objectives assigned to the representative wells. 7.3.3 Seawater Intrusion The Basin is not susceptible to seawater intrusion and will not be monitored for that indicator. 7.3.4 Degraded Groundwater Quality The significant and unreasonable degradation of water quality would be an undesirable result. As discussed in Section 7.2.2, groundwater quality constituents in the Basin that have been selected for groundwater quality indicator monitoring include TDS, Nitrate, and Arsenic. Selenium has been observed at concentrations that affect well operations at individual wells in the Basin, but it does not appear to be a widespread issue (Chapter 5; Section 5.9.3.5). The selected water quality indicators represent common constituents of concern in relation to groundwater production for domestic, municipal and agricultural use that will be assessed by the monitoring network. TDS is selected as a general indicator of groundwater quality in the Basin. Nitrate is a widespread contaminant in California groundwater and selected due to its presence across the Basin associated with agricultural activities, septic systems, landscape fertilizer and wastewater treatment facilities. Arsenic is selected to represent naturally occurring contaminants in the Basin. Other constituents of concern may be added to the list during GSP implementation. The sites currently best suited for evaluating trends over time are public supply wells. Sampling intervals vary by well and by constituent, ranging from every three years to monthly, but longer historical records are available, compared to other types of wells. The significant and unreasonable degradation of water quality includes the migration of contaminant plumes that impair water supplies. There are two anthropogenic contaminant plumes that underly multiple properties and are under investigation within the Basin. These include a tetrachloroethylene (PCE) plume, also known as the South SLO PCE Plume, and a trichloroethylene (TCE) plume, also known as the Buckley Road Area plume (Figure 7-2). 7.3.4.1 South SLO PCE Plume PCE is primarily used as a solvent at dry cleaning establishments and has a maximum contaminant level in drinking water of 5 micrograms per liter. Dissolved PCE in groundwater has been detected underlying portions of the City of San Luis Obispo, mainly south of the confluence of San Luis Obispo Creek and Stenner Creek. There have been several site investigations and documented PCE releases at various locations within the City. Historical site investigations date to the early 1990's, with regional investigations in 2005 (QPS, 2005) and 2013-2015 (URS, 2013), (URS, 2015). The Department of Toxic Substance Control (DTSC) and the Regional Water Quality Control Board (RWQCB) have provided most of the regulatory oversight related to site investigations and clean-up efforts since the early 1990's. Currently, the City has initiated a comprehensive PCE investigation, including monitoring well constructions, with Proposition 1 grant funding. Representative wells from the future PCE monitoring well network will be selected for inclusion with the GSP groundwater quality network specifically for tracking PCE in the Basin. 7.3.4.2 Buckley Road Area TCE Plume TCE has a variety of uses, typically as an industrial solvent/degreaser. The maximum contaminant level for TCE in drinking water is 5 micrograms per liter. In 2013, the RWQCB initiated an investigation into the 15 Page 334 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO source of TCE detected in two supply wells in the industrial area of Buckley Road and Thread Lane. County of San Luis Obispo Environmental Health Services also began a sampling program following TCE detection above the maximum contaminant level in groundwater from a residential supply well in 2015. Information from these and subsequent investigations, including investigation at the San Luis Obispo County Airport north of Buckley Road, indicated that the likely source of TCE was the industrial area of Buckley Road and Thread Lane. These investigations were summarized in a public notice from the RWQCB dated January 15, 2019. One of the supply wells selected for the groundwater quality network (WQ-5) is in the industrial area and both historically and currently reports TCE concentrations above the maximum contaminant level (24 micrograms per liter TCE reported in April 2020). Currently, the RWQCB is enforcing a replacement water program to provide treatment for wells impacted by the TCE plume. A web page has been established by the Water Board to provide the latest information to the public and can be accessed here: https://www.waterboards.ca.gov/centralcoast/water issues/hot topics/tce pce info/tce pce index.html. The TCE plume will be monitored for the GSP through tracking the concentration reported at WQ-5 and observing published plume maps over time. A general trend of decreasing TCE concentration, along with plume containment, would be measures of success in plume management. 7.3.5 Land Subsidence Land subsidence can lead to undesirable results when it interferes with surface land uses. Land subsidence is frequently associated with groundwater pumping and has been documented in the San Luis Valley subarea (see Chapter 4; Section 4.7 and Chapter 6; Section 6.7.3). The purpose of land subsidence monitoring is to identify the rate and extent of land subsidence and to provide data for sustainability criteria thresholds. DWR maintains a land subsidence dataset derived from Interferometric Synthetic Aperture Radar (InSAR) data from satellite imagery. InSAR is a remote sensing method used to measure land -surface elevations over large areas, with accuracy on the order of centimeters to millimeters. InSAR uses satellites that emit and measure electromagnetic waves that reflect off of the earth's surface to produce synthetic aperture radar images with a spatial resolution of about 100 meters by 100 meters. Vertical displacement values associated with land subsidence can be estimated by comparing these images over time. The DWR land subsidence dataset shows vertical displacement from 2015-2019 in California groundwater basins. The raster GIS dataset covers the entire Basin, with no data gaps. The dataset shows minimal vertical displacement of less than an inch from 2015-2019 throughout the Basin (Chapter 8). Continued evaluation of Basin land subsidence through monitoring the available InSAR data is planned. In addition, two representative monitoring site wells have been identified for land subsidence monitoring based on the historical area of land subsidence in the Basin (Chapter 4; Section 4.7) and are included in Table 7-2. Groundwater level can be a proxy for land subsidence because the process is typically not reversible, and maintaining groundwater levels above historic lows in areas susceptible to land subsidence can protect against future undesirable results (see Chapter 8). 7.3.6 Depletion of Interconnected Surface Water Surface water provides beneficial uses, and depletion of interconnected surface water due to groundwater pumping can result in undesirable results by impacting these beneficial uses. The purpose of monitoring for depletion of interconnected surface water is to characterize the following: • Flow conditions including surface water discharge, surface water head, and baseflow contribution. • Identifying the approximate date and location where ephemeral or intermittent flowing streams cease to flow. • Historical change in conditions due to variations in stream discharge and regional groundwater extraction. 16 Page 335 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO • Other factors that may be necessary to identify adverse impacts on beneficial uses of the surface water. One of the beneficial uses of surface water is the environmental water demand which supports riverine, riparian, and wetland ecosystems. Locations where surface water is interconnected with groundwater have the potential for creating GDEs, which are ecological communities or species that depend on groundwater emerging from aquifers (rising into streams or lakes) or on groundwater occurring near ground surface where it may be used by riparian vegetation, wetland vegetation, or oak woodlands. Depending on location and time of year, GDEs that overlie the Basin can be supported by a range of water sources including direct precipitation, surface runoff, shallow subsurface flow, and groundwater. Shallow subsurface flow can vary from short-term precipitation and runoff driven flow (e.g. bank storage and other macro -pores filled during a precipitation event that drain on the order of days to weeks) to flow that is directly connected to groundwater (e.g. baseflow as groundwater discharge into streams during the dry season). Because GDEs overlying the Basin are supported by a wider range of surface and groundwater hydrological processes in the wet season, monitoring of GDEs for sustainability indicators will focus on the late spring baseflow period and summer/early fall dry season. Primary groundwater dependence for GDEs is more likely during the late spring, summer, and early fall dry season, although in some reaches irrigation return flow may also be a factor. If the GDE indicators are met in the late spring and dry summer and fall seasons, sufficient groundwater is more likely also be available in the wet season to sustain GDEs (see Appendix 7A). There are six existing County stream gages within, or adjacent to the SLO Valley Groundwater Basin (Table 7-4, Figure 7-3). The existing gages only report stage, as discussed in Section 7.2.3. An additional five stream gages are proposed, both for water budget and interconnected surface water flow data gaps (Table 7-5). Rating curves, which correlate stage with stream flows, should be developed for all 11 sites. In addition, groundwater level monitoring is recommended near the stream gages sites, and at additional sites for riparian and wetland/marsh GDE types (Figure 7-3). Table 7-6 shows the pairing between the stream gages and the nearby water level monitoring sites for interconnected surface water and GDE indicator evaluation (both existing and recommended). 17 Page 336 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO Table 7-6 Interconnected Surface Water and Associated GDE indicator Monitoring Locations Stream Gage Monitoring Well Area SG-745 (none - bedrock) SLO Creek near upstream Basin boundary SG-781 SLV-5 Stenner Creek above SLO Creek confluence SG-790 SLV-5 SLO Creek below Stenner Creek confluence SG-740 WL-C SLO Creek at Elks Lane SG-778 WL-B Prefumo Creek at Laguna Lake outlet SG-783 SLV-19 East Fork SLO Creek at Jesperson Lane SG -A SLV-01 Stenner Creek near upstream Basin boundary SG-B WL-D SLO Creek near downstream Basin boundary SG-C EV-2 West Corral de Piedra at Orcutt Road SG-D EV-8 East Corral de Piedra at Orcutt Road SG-E EV-11 Pismo Creek at downstream Basin boundary (none) SLV-12 Calle Joaquin (none) SLV-13 Tank Farm Road (none) WL-E Davenport Creek near Crestmont Road (none) WL-F Corbett Canyon Road near Canada Verde The wells in Table 7-6 used for GDE monitoring need to be in locations that are representative of groundwater levels in the riparian zones. A few of the existing wells (SLV-5, SLV-19, EV-11) are not immediately adjacent to their paired stream gage, but may have a sufficient hydraulic connection to local riparian conditions to be useful for GDE indicator evaluation. The data for each paired monitoring well and stream gage would be supplemented with field surveys (discussed below), to evaluate the suitability of the GDE indicator monitoring sites. In addition to streamflow and groundwater level monitoring, streamflow surveys are recommended across a range of seasons and water year types to identify losing and gaining reaches with the Basin. Identifying losing and gaining reaches is fundamental to understanding surface water -groundwater connectivity. Losing reaches occur in Basin recharge areas that are typically dry during the summer and late fall. Gaining reaches occur in Basin discharge areas where groundwater is contributing to surface water flow. Groundwater pumping that lowers groundwater levels in an aquifer beneath a creek channel may deplete surface water by either expanding a losing reach or contracting a gaining reach, depending on the depth of the water table and the permeability of the stream bed. The streamflow surveys characterize the extent of gaining and losing reaches and help evaluate depletion of interconnected streamflow. This type of data collection is conducted by measuring instream flow in multiple locations along a reach of creek in a short period of time and examining the loss or gain of stream flow rates along the length of the stream channel. 7.4 MONITORING TECHNICAL AND REPORTING STANDARDS Monitoring technical and reporting standards include a description of the protocols, standards for monitoring sites, and data collection methods. 18 Page 337 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO 7.4.1 Groundwater Levels Monitoring protocols and data collection methods for groundwater level monitoring and reporting are described in the attached Appendix 7C, and are based on SGMA monitoring protocols, standards and sites BMPs, USGS data collection methods, and practical experience. Wells used for monitoring program sites have been constructed according to applicable construction standards, although not all the information required under the BMPs is available for every site. Table 7-2 lists the pertinent information available for the monitoring sites. 7.4.2 Groundwater Quality Monitoring protocols and standards for groundwater quality sampling sites are those required for public water systems from which the groundwater quality data is obtained. Sample collection and field tests shall be performed by appropriately trained personnel as required by California Code of Regulations Title 22, Section 64415. All wells used for public supply are expected to meet applicable construction standards. 7.4.3 Surface Water Flow As previously discussed, the existing gaging stations only provide stage data, and not actual stream flow data. Stage data can be converted to streamflow through the use of a rating curve, which incorporates information that is specific to each site, including the cross -sectional area of the channel and the average surface water velocity for a given flow stage. These rating curves are developed using depth profiles and flow velocity measurements during storm -runoff events (Appendix 7B). Rating curves may need to be revised periodically as they can shift due to changes in channel geometry. Protocols and data collection methods will be based on applicable USGS standards and SLOFCWCD standards. 7.4.4 Monitoring Frequency Monitoring frequency is the time interval between data collection. Seasonal fluctuations relating to groundwater levels or quality are typically on quarterly or semi-annual cycles, correlating with seasonal precipitation, recharge, groundwater levels, and well production. The monitoring schedule for groundwater levels collected under the GSP groundwater level monitoring program will coincide with seasonal groundwater level fluctuations, with higher levels (i.e. elevations) in April (Spring) and lower levels in October (Fall). A semi-annual monitoring frequency provides a measure of seasonal cycles, which can then be distinguishable from the long-term trends. At the transducer -monitored locations, groundwater level measurements will be recorded automatically on a daily basis and downloaded during the regular semi- annual groundwater level monitoring events. Daily measurements provide the same time -step as the Basin model, and will also allow direct correlation with daily stream flow data. The monitoring frequency for groundwater quality sampling is variable and based on the schedule determined by the regulating agency (County Environmental Health Services for small public water systems and the State Division of Drinking Water for large public systems). TDS is typically monitored every three years, while nitrate and arsenic may be monitored annually, quarterly, or even monthly at vulnerable systems. The frequency selected for monitoring individual constituents at each system is sufficient to protect public health, and therefore considered sufficient for Basin management purposes. Surface monitoring network frequency is a near -continuous record of flow stage, collected at 15-minute intervals. The stage data can then be converted to average daily flow (cubic feet per second) using a rating curve. Automatic gaging equipment (e.g. radar sensors or bubbler gages) at proposed flow monitoring locations will maintain the near -continuous monitoring frequency. Rating curves are needed at all gage sites, which requires manual flow measurements over a range of stream stages. New and existing wells listed in Table 7-6 used for interconnected surface water and GDE indicator evaluation may also be equipped with 19 Page 338 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO groundwater level transducers, either upon construction (for network additions) or when the recommended nearby stream gage is installed. 7.5 DATA MANAGEMENT SYSTEM SGMA requires development of a Data Management System (DMS). The DMS stores data relevant to development of a groundwater Basin's GSP as defined by the GSP Regulations (California Code of Regulations, Title 23, Division 2, Chapter 1.5, Subchapter 2). To comply with SGMA, the Basin DMS was developed in this GSP and will store data that is relevant to development and implementation of the GSP as well as for monitoring and reporting purposes. Appendix 7D describes the data management plan associated with the DMS. 7.6 ASSESSMENT AND IMPROVEMENT OF MONITORING NETWORK The current assessment of the monitoring networks has identified data gaps that will be filled during the implementation phase of the GSP and prior to the first five-year assessment. These data gaps, consisting of six groundwater level monitoring sites and five surface water flow monitoring sites, are listed in Tables 7-2 and 7-4 and shown in Figures 7-1 and 7-3. As previously mentioned, obtaining well construction information for all monitoring network wells is not an immediate necessity or a requirement for Basin management purposes, provided the lack of information does not affect the usefulness of the monitoring results toward Basin management. Over time, wells for which construction information is not known will be inspected with a video camera to document construction, either within the next five years or at the earliest practical opportunity, such as when the well pump is being serviced. The monitoring networks will be re-evaluated at each five-year assessment. 7.7 ANNUAL REPORTS AND PERIODIC EVALUATION BY THE GSAs Reporting requirements for the Annual Report and for periodic evaluation of the GSP are contained in Article 7 of the GSP regulations. The GSAs will submit an Annual Report that meets Article 7 regulations by April 1 of each year following adoption of the GSP, with the first Annual Report anticipated in 2022. Periodic evaluations of the GSP, including the monitoring networks, will be performed at least every five years and whenever the GSP is amended, with the first written evaluation anticipated no later than 2027. 20 Page 339 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO REFERENCES Balance Hydrologics. 2008. Hydrology and Geology Assessment of the Pismo Creek Watershed, San Luis Obispo County, California. 2008. Blaney. 1963. Utilization of the Water of the Santa Ynez River Basin in Southern Santa Barbara County California, United Stated Deparment of Agriculture. 1963. -. 1933. Ventura County Investigation, Bulletin No. 46, California Deparment of Public Works, Division of Water Resources. 1933. Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. CIMS. 2019. Station 52, San Luis Obispo - Central Coast Valleys. 2019. City of San Luis Obispo. 2016. 2015 Urban Water Management Plan. 2016. -. 2018. General Plan. 2018. -. 2015. Water Resources Status Report. 2015. -. 2000. Water Use Factors. 2000. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. -. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists. 2018. Groundwater Flow Analysis, Recycled Water Recharge Project, San Luis Valley Subarea, San Luis Obispo Valley Groundwater Basin. 2018. -. 2019. Optional Task 2.4B Geophysical Survey. 2019. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. -. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. -. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2015. Consumptive Use Program Plus (CUP+) Model, in California Water Plan Update 2013, Volume 4. Reference Guide, Developed by DWR and UC Davis. 2015. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. 21 Page 340 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 1996. South Central Coast Land Use Survey. 1996. -. 1987. Southern Central Coast Land Use Survey, 1985. Morro Bay South 54-30 and San Luis Obispo 54-31 Survey Maps. 1987. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. -. 2016. Water Budget Best Management Practices for the Sustainable Management of Groundwater. 2016. -. 2002. Water Resources of the Arroyo Grande - Nipomo Mesa Area. 2002. EPA. 2008. Water Sense Factsheet - Indoor Water Use in the United States, EPA-832-F-06-004. 2008. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study. September. 1994. Fugro West and Cleath & Associates. 2002. Paso Robles Groudnwater Study, Final Report. 2002. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. Hall, C.A. 1979. Geologic map of the San Luis Obispo - San Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. -. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. ITRC. 2020. Official Cal Poly Precipitation Data, Cal Poly/NOAA Station Rain Gage. 2020. Johnson, A.I. 1967. Specific Yield - Compilation of Specific Yield for Various Materials, U.S. Geological Survey Water -Supply Paper 1662-D, prepared in cooperation with the California Deparment of Water Resources. 1967. National Land Cover Database. Multi -Resolution Land Characteristics Consortium. 2016. Multi -Resolution Land Characteristics Consortium. QPS. 2005. DRAFT Background Study South San Luis Obispo Groundwater PCE Plume. 2005. Rosenberg, L.I. 2001. Potential Aquifer Recharge Areas: Monterey County, California. s.1.: Monterey County Planning Department, 2001. San Luis Obispo County Deparment of Agriculture/Weights and Measures. 2019. Crop Surveys for San Luis Obispo Valley Groundwater Basin 2013-2018. 2019. San Luis Obispo County Department of Public Works. 2020. Andrews Street Bridge Stream Flow Gage 745. 2020. -. 2020. Gas Company Rain Sensor 3099. 2020. San Luis Obispo County Engineering Department. 1974. Hydrologic & Climatological Data, Seasons of 1970-71 & 1971-72. 1974. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. SWRCB. 1990. Ernest Righetti & Sons Application 28883, Decision 1627. 1990. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. URS. 2013. Final Investigation Report: San Luis Obispo PCE Groundwater Plume. 2013. -. 2015. Investigation Report: San Luis Obispo PCE Groundwater Plume. 2015. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.l.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. 22 Page 341 of 1183 SLO Basin Groundwater Sustainability Plan Monitoring Networks (§ 354.32 and § 354.34) County of SLO and City of SLO USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. 23 Page 342 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO 8 APPENDICES APPENDIX 7A - GROUNDWATER -DEPENDENT ECOSYSTEMS IN THE SAN LUIS OBISPO VALLEY GROUNDWATER BASIN (Will be included with the release of Chapter 8 — Sustainable Management Criteria) 24 Page 343 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO APPENDIX 7B - GROUNDWATER LEVEL MEASUREMENT PROCEDURES FOR THE SAN LUIS OBISPO VALLEY GROUNDWATER BASIN GSP 25 Page 344 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO Groundwater Level Measurement Procedures for the San Luis Obispo Valley Groundwater Basin GSP Introduction This document establishes procedures for measuring and recording groundwater levels for the SLO Basin Groundwater Monitoring Program, and describes various methods used for collecting meaningful groundwater data. Static groundwater levels obtained for the groundwater monitoring program are determined by measuring the distance to water in a non -pumping well from a reference point that has been referenced to sea level. Subtracting the distance to water from the elevation of the reference point determines groundwater surface elevations above or below sea level. This is represented by the following equation: EGW = ERP— D Where: EGW = Elevation of groundwater above mean sea level (feet) ERP Elevation above sea level at reference point (feet) D = Depth to water (feet) References Procedures for obtaining and reporting water level data for the SLO Basin Groundwater Monitoring Program are based on a review of the following documents. • State of California, Department of Water Resources, 2016, Best Management Practices for the Sustainable Management of Groundwater: Monitoring Protocols, Standards, and Sites, December 2016. • State of California, Department of Water Resources, 2014, Addendum to December 2010 Groundwater Elevation Monitoring Guidelines for the Department of Water Resources' California Statewide Groundwater Elevation Monitoring (CASGEM) Program, October 2, 2014. • State of California, Department of Water Resources, 2010, Groundwater Elevation Monitoring Guidelines, prepared for use in the California Statewide Groundwater Elevation Monitoring (CASGEM) program, December 2010. • U.S. Geological Survey, 2011, Groundwater Technical Procedures of the U.S. Geological Survey, Techniques and Methods 1-A1, compiled by William L. Cunningham and Charles W. Schalk. • U.S. Geological Survey, 1977, National Handbook of Recommended Methods for Water -Data Acquisition, a Unites States contribution to the International Hydrological Program. Well Information Table 1 below lists important well information to be maintained in a well file or in a field notebook. Additional information that should be available to the person collecting water level data include a description of access to the property and the well, the presence and depth of cascading water, or downhole obstructions that could interfere with a sounding cable. 26 Page 345 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table 1 Well File Information Appendices Well Completion Report Hydrologic Information Additional Information to be Recorded Well name Map showing basin boundaries and wells Township, Range, Section and %-% Section Well Owner Name of groundwater basin Latitude and Longitude (Decimal degrees) Drilling Company Description of aquifer Assessor's Parcel Number Location map or sketch Confined, unconfined, or mixed aquifers Description of well head and sounding access Total depth Pumping test data Reference point elevations Perforation interval Hydrographs Well use and pumping schedule if known Casing diameter Water quality data Date monitoring began Date of well completion Property access instructions/codes Land use Reference Points and Reference Marks Reference point (RP) elevations are the basis for determining groundwater elevations relative to sea level. The RP is generally a point on the well head that is the most convenient place to measure the water level in a well. In selecting an RP, an additional consideration is the ease of surveying either by Global Positioning System (GPS) or by leveling. The RP must be clearly defined, well marked, and easily located. A description, sketch, and photograph of the point should be included in the well file. Additional Reference Marks (RMs) may be established near the wellhead on a permanent object. These additional RMs can serve as a benchmark by which the wellhead RP can be checked or re -surveyed if necessary. All RMs should be marked, sketched, photographed, and described in the well file. All RPs for Groundwater Monitoring Program wells should be reported based on the same horizontal and vertical datum by a California licensed surveyor to the nearest tenth of one foot vertically, and the nearest one foot horizontally. The surveyor's report should be maintained in the project file. In addition to the RP survey, the elevation of the ground surface adjacent to the well should also be measured and recorded in the well file. Because the ground surface adjacent to a well is rarely uniform, the average surface level should be estimated. This average ground surface elevation is referred to in the USGS Procedural Document (GWPD-1) and DWR guidelines as the Land Surface Datum. Water Level Data Collection Prior to beginning the field work, the field technician should review each well file to determine which well owners require notification of the upcoming site visit, or which well pumps need to be turned off to allow for sufficient water level recovery. Because groundwater elevations are used to construct groundwater contour maps and to determine hydraulic gradients, the field technician should coordinate water level measurements to be collected within as short a period of time as practical. Any significant changes in groundwater conditions during monitoring events should be noted in the Annual Monitoring Report. For an individual well, the same measuring method and the same equipment should be used during each sampling event where practical. 27 Page 346 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO A static water level should represent stable, non -pumping conditions at the well. When there is doubt about whether water levels in a well are continuing to recover following a pumping cycle, repeated measurements should be made. If an electric sounder is being used, it is possible to hold the sounder level at one point slightly above the known water level and wait for a signal that would indicate rising water. If applicable, the general schedule of pump operation should be determined and noted for active wells. If the well is capped but not vented, remove the cap and wait several minutes before measurement to allow water levels to equilibrate to atmospheric pressure. When lowering a graduated steel tape (chalked tape) or electric tape in a well without a sounding tube in an equipped well, the tape should be played out slowly by hand to minimize the chance of the tape end becoming caught in a downhole obstruction. The tape should be held in such a way that any change in tension will be felt. When withdrawing a sounding tape, it should also be brought up slowly so that if an obstruction is encountered, tension can be relaxed so that the tape can be lowered again before attempting to withdraw it around the obstruction. Despite all precautions, there is a small risk of measuring tapes becoming stuck in equipped wells without dedicated sounding tubes. If a tape becomes stuck, the equipment should be left on -site and re -checked after the well has gone through a few cycles of pumping, which can free the tape due to movement/vibration of the pump column. If the tape remains stuck, a pumping contractor will be needed to retrieve the equipment. A dedicated sounding tube may be installed by the pumping contractor at that time. All water level measurements should be made to an accuracy of 0.01 feet. The field technician should make at least two measurements. If measurements of static levels do not agree to within 0.02 feet of each other, the technician should continue measurements until the reason for the disparity is determined, or the measurements are within 0.02 feet. Record Keeping in the Field The information recorded in the field is typically the only available reference for the conditions at the time of the monitoring event. During each monitoring event it is important to record any conditions at a well site and its vicinity that may affect groundwater levels, or the field technician's ability to obtain groundwater levels. Table 2 lists important information to record, however, additional information should be included when appropriate. Table 2 Information Recorded at Each Well Site Well name Changes in land use Presence of pump lubricating oil in well Name and organization of field technician Changes in RP Cascading water Date & time Nearby wells in use Equipment problems Measurement method used Weather conditions Physical changes in wellhead Sounder used Recent pumping info Comments Reference Point Description Measurement Well status correction(s) An example of a field log sheet from DWR is attached. W Page 347 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Measurement Techniques Appendices Four standard methods of obtaining water levels are discussed below. The chosen method depends on site and downhole conditions, and the equipment limitations. In all monitoring situations, the procedures and equipment used should be documented in the field notes and in final reporting. Additional detail on methods of water level measurement is included in the reference documents. Graduated Steel Tape This method uses a graduated steel tape with a brass or stainless steel weight attached to its end. The tape is graduated in feet. The approximate depth to water should be known prior to measurement. • Estimate the anticipated static water level in the well from field conditions and historical information; • Chalk the lower few feet of the tape by applying blue carpenter's chalk. • Lower the tape to just below the estimated depth to water so that a few feet of the chalked portion of the tape is submerged. Be careful not to lower the tape beyond its chalked length. • Hold the tape at the RP and record the tape position (this is the "hold" position and should be at an even foot); • Withdraw the tape rapidly to the surface; • Record the length of the wetted chalk mark on the graduated tape; • Subtract the wetted chalk number from the "hold" position number and record this number in the "Depth to Water below RV column; • Perform a check by repeating the measurement using a different RP hold value; • All data should be recorded to the nearest 0.01 foot; • Disinfect the tape by wiping down the submerged portion of the tape with single -use, unscented disinfectant wipe, or let stand for one minute in a dilute chlorine bleach solution and dry with clean cloth. The graduated steel tape is generally considered to be the most accurate method for measuring static water levels. Measuring water levels in wells with cascading water or with condensing water on the well casing causes potential errors, or can be impossible with a steel tape. Electric Tape An electric tape operates on the principle that an electric circuit is completed when two electrodes are submerged in water. Most electric tapes are mounted on a hand -cranked reel equipped with batteries and an ammeter, buzzer or light to indicate when the circuit is completed. Tapes are graduated in either one - foot intervals or in hundredths of feet depending on the manufacturer. Like graduated steel tapes, electric tapes are affixed with brass or stainless steel weights. • Check the circuitry of the tape before lowering the probe into the well by dipping the probe into water and observe if the ammeter needle or buzzer/light signals that the circuit is completed; • Lower the probe slowly and carefully into the well until the signal indicates that the water surface has been reached, • Place a finger or thumb on the tape at the RP when the water surface is reached; • If the tape is graduated in one -foot intervals, partially withdraw the tape and measure the distance from the RP mark to the nearest one -foot mark to obtain the depth to water below the RP. If the tape is graduated in hundredths of a foot, simply record the depth at the RP mark as the depth to water below the RP; • Make all readings using the same needle deflection point on the ammeter scale (if equipped) so that water levels will be consistent between measurements; 29 Page 348 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO • Make check measurements until agreement shows the results to be reliable; • All data should be recorded to the nearest 0.01 foot; • Disinfect the tape by wiping down the submerged portion of the tape with single -use, unscented disinfectant wipe, or let stand for one minute in a dilute chlorine bleach solution and dry with clean cloth; • Periodically check the tape for breaks in the insulation. Breaks can allow water to enter into the insulation creating electrical shorts that could result in false depth readings. The electric tape may give slightly less accurate results than the graduated steel tape. Errors can result from signal "noise" in cascading water, breaks in the tape insulation, tape stretch, or missing tape at the location of a splice. All electric tapes should be calibrated annually against a steel tape that is maintained in the office and used only for calibration. Air Line The air line method is usually used only in wells equipped with pumps. This method typically uses a 1/8 or 1/4-inch diameter, seamless copper tubing, brass tubing, stainless steel tubing, or galvanized pipe with a suitable pipe tee for connecting an altitude or pressure gage. Plastic (i.e. polyethylene) tubing may also be used, but is considered less desirable because it can develop leaks as it degrades. An air line must extend far enough below the water level that the lower end remains submerged during pumping of the well. The air line is connected to an altitude gage that reads directly in feet of water, or to a pressure gage that reads pressure in pounds per square inch (psi). The gage reading indicates the length of the submerged air line. The formula for determining the depth to water below the RP is: d = k — h where d = depth to water; k = constant; and h = height of the water displaced from the air line. In wells where a pressure gage is used, h is equal to 2.31 ft/psi multiplied by the gage reading. The constant value for k is approximately equivalent to the length of the air line. Calibrate the air line by measuring an initial depth to water (d) below the RP with a graduated steel tape. Use a tire pump, air tank, or air compressor to pump compressed air into the air line until all the water is expelled from the line. When all the water is displaced from the line, record the stabilized gage reading (h). Add d to h to determine the constant value for k. To measure subsequent depths to water with the air line, expel all the water from the air line, subtract the gage reading (h) from the constant k, and record the result as depth to water (d) below the RP. The air line method is not as accurate as a graduated steel tape or electric and is typically accurate to the nearest one foot at best. Errors can occur from leaky air lines, or when tubing becomes clogged with mineral deposits or bacterial growth. The air line method is not desirable for use in the Groundwater Monitoring Program. Pressure Transducer Electrical pressure transducers make it possible to collect frequent and long-term water level or pressure data from wells. These pressure -sensing devices, installed at a fixed depth in a well, sense the change in pressure against a membrane. The pressure changes occur in response to changes in the height of the water column in the well above the transducer membrane. To compensate for atmospheric changes, transducers may have vented cables or they can be used in conjunction with a barometric transducer that is installed in the same well or a nearby observation well above the water level. 30 Page 349 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO Transducers are selected on the basis of expected water level fluctuation. The smallest range in water levels provides the greatest measurement resolution. Accuracy is generally 0.01 to 0.1 percent of the full scale range. Retrieving data in the field is typically accomplished by downloading data through a USB connection to a portable computer or data logger. A site visit to retrieve data should involve several steps designed to safeguard the stored data and the continued useful operation of the transducer: • Inspect the wellhead and check that the transducer cable has not moved or slipped (the cable can be marked with a reference point that can be used to identify movement); • Ensure that the instrument is operating properly; • Measure and record the depth to water with a graduated steel or electric tape; • Document the site visit, including all measurements and any problems; • Retrieve the data and document the process; • Review the retrieved data by viewing the file or plotting the original data; • Recheck the operation of the transducer prior to disconnecting from the computer. A field notebook with a checklist of steps and measurements should be used to record all field observations and the current data from the transducer. It provides a historical record of field activities. In the office, maintain a binder with field information similar to that recorded in the field notebook so that a general historical record is available and can be referred to before and after a field trip. Quality Control The field technician should compare water level measurements collected at each well with the available historical information to identify and resolve anomalous and potentially erroneous measurements prior to moving to the next well location. Pertinent information, such as insufficient recovery of a pumping well, proximity to a pumping well, falling water in the casing, and changes in the measurement method, sounding equipment, reference point, or groundwater conditions should be noted. Office review of field notes and measurements should also be performed by a second staff member. All field tapes (both steel and electric) used for the monitoring program should be calibrated annually against another acceptable steel tape. An acceptable steel tape is one that is maintained in the office for use only in calibrating the field tapes. Adjustments for tape calibration should be applied and noted. 31 Page 350 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices DecemNr 2016 Groundwater Monitoring Protocols, Standards, and Sites BMP DWR 1212 STATE OF CALJFORNA THE RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES WELL DATA STATE WELL NUM$ER COUNTY REFERENCE POINT ELEV. MEASURING AGENCf DWR NO MEASUREMENT 0. Measurementdisco-rninuej 1. Pumping 2. Pump house locked 3. Tap¢ hung up 4. Can't get tape in casing S. Unable to locate well 6. Well has Ibsen destroyed 7. Special B. Casing leakyor wet 4. Temporarilyinaccessible QU ESTIONABLE M EASUREMENT 0. Caved ordeepened 1. Pumping 2. Nearby pump operating I Casing lanky or wot 4. Pumped recernly i. Air or pressure gauge measurement 6. Other 7. Recharge operation at or nearbywelI 8. Oil in casing DATE N Ir1 4 M TAPE AT RP TAPE AT WS RP to WS OBSR V41 COMMENTS Figure 4 — Example of Water Level Well Data Field Collection Farm California Department of Water Resources 12 32 Page 351 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO /.1»DI►III K►L11s.`JIYNDFROII1111VA61DFA411NDIOID1►YIII1►ILI/.r111.7.11[MOk101►1DlR Appendices 33 Page 352 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Streamflow Measurement in Natural Channels Appendices The most practical method for measuring streamflow in natural channels is the velocity -area method, which has the following computation': n Q = Y(aivi) i=1 where: Q = total discharge (reported in cubic feet per second). ai = cross -sectional area of flow for the ith segment of the n segments into which the cross section is divided (square feet), and vi = the corresponding mean velocity of flow normal to the ith segment (feet per second). The conceptual model for the velocity area -method is shown below. A stream is divided into segments, each with an individual area and velocity, which are then multiplied and summed using the above equation. Subsection I � Width LIJ,) In each subsection: Area = Depth x Width Velocity Depth Discharge = Area x Diagram of Channel cross-section with segments for discharge computation (USGS) In natural channels, stream gages are used to record stage (feet), which is the height of water in the stream above an arbitrary point, usually at or below the stream bed. The stage is then converted to streamflow through the use of a rating curve, or stage -discharge relation. A rating curve incorporates information collected that is specific to each site, including the cross -sectional area of i Turnipseed, D.P. and Sauer, V.B., 2010. Discharge Measurements at Gaging Stations, USGS Techniques and Methods 3-A8. 34 Page 353 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Appendices the channel and the average velocity for a given flow stage. These rating curves are developed using depth profiles and average flow velocity measurements during storm -runoff events. Rating curves may need to be revised periodically as they can shift due to changes in channel geometry. Measuring average flow velocity across a channel at different stream stages is the most challenging part of developing a rating curve. 35 Page 354 of 1183 SLO Basin Groundwater Sustainability Plan Appendices County of SLO and City of SLO /:1»0ILII11KIWA01007:vr:11ur:R►kTHDid ID1►Y8UW.11 1 (Draft Data Management Plan was released for public comment following the September 9`" GSC Meeting and may be found at https://www.slowaterbasin.com/review-documents) 36 Page 355 of 1183 DRAFT Chapter 8 - Sustainable Management Criteria San Luis Obispo Valley Basin Groundwater Sustainability Plan Available for viewing in the May 5, 2021 Agenda Packet: April 28, 2021 Recommended the GSAs to receive and file for public comments: May 5, 2021 Available for public comments on www.slowaterbasin.com: May 6, 2021 Close of public comment period: June 6, 2021 Per the GSC's recommendation on May S, 2021, GSP Draft Chapter 8 - Sustainable Management Criteria will be distributed to the City and County GSAs to receive and file. This draft document is now posted on the web portal: www.slowaterbasin.com for public comments. Comments from the public are being collected using a comment form available at www.slowaterbasin.com by clicking on "Submit Comment". If you require a paper form to submit by postal mail, please contact your local Groundwater Sustainability Agency (GSA). All comments submitted will also be posted online for viewing. Page 356 of 1183 IM Groundwater Sustainability Plan Chapter 8 — Sustainable Management Criteria forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by S C WATER SYSTEMS CONSULTING, INC. HG GE1consultants Stillwater SCienCeSwater5alutions,Inc. X 4/28/2021 Page 357 of 1183 SLO Basin Groundwater Sustoinability Plan Table of Contents County of SLO and City of SLO TABLE OF CONTENTS Tableof Contents........................................................................................................................................... i Listof Figures................................................................................................................................................ x Tables........................................................................................................................................................... xi Appendices.................................................................................................................................................. xii Listof Terms Used.......................................................................................................................................xiii ExecutiveSummary.......................................................................................................................................1 1 Introduction to the SLO Basin GSP......................................................................................................... 1.1 Purpose of the Groundwater Sustainability Plan............................................................................ 1.2 Description of SLO Basin................................................................................................................. 1.3 Basin Prioritization.......................................................................................................................... 2 Agency Information (§ 354.6)................................................................................................................ 2.1 Agencies Names and Mailing Addresses......................................................................................... 2.2 Agencies Organization and Management Structures..................................................................... 2.2.1 County of San Luis Obispo....................................................................................................... 2.2.2 City of San Luis Obispo............................................................................................................ 2.2.3 Other Participating Parties in the MOA.................................................................................. 2.2.3.1 Edna Valley Growers Mutual Water Company............................................................... 2.2.3.2 Varian Ranch Mutual Water Company........................................................................... 2.2.3.3 Edna Ranch Mutual Water Company.............................................................................. 2.2.3.4 Golden State Water Company........................................................................................ 2.3 Authority of Agencies...................................................................................................................... 2.3.1 Groundwater Sustainability Agencies..................................................................................... 2.3.1.1 County of San Luis Obispo............................................................................................... 2.3.1.2 City of San Luis Obispo.................................................................................................... 2.3.2 Memorandum of Agreement.................................................................................................. 2.3.3 Coordination Agreements....................................................................................................... 2.4 Contact information for Plan Manager........................................................................................... 3 Description of Plan Area (§ 354.8)......................................................................................................... 3.1 SLO Basin Introduction.................................................................................................................... 3.2 Adjudicated Areas........................................................................................................................... 3.3 Jurisdictional Areas......................................................................................................................... 3.3.1 Federal Jurisdictions................................................................................................................ 3.3.2 Tribal Jurisdiction.................................................................................................................... i Page 358 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Table of Contents 3.3.3 State Jurisdictions................................................................................................................... 3.3.4 County Jurisdictions................................................................................................................ 3.3.5 City and Local Jurisdictions..................................................................................................... 3.3.6 Special Districts....................................................................................................................... 3.4 Land Use.......................................................................................................................................... 3.4.1 Water Source Types................................................................................................................ 3.4.2 Water Use Sectors................................................................................................................... 3.5 Density of Wells.............................................................................................................................. 3.6 Existing Monitoring and Management Programs........................................................................... 3.6.1 Groundwater Monitoring........................................................................................................ 3.6.1.1 Groundwater Level Monitoring...................................................................................... 3.6.1.2 Groundwater Quality Monitoring.................................................................................. 3.6.1.3 Surface Water Monitoring.............................................................................................. 3.6.1.4 Climate Monitoring......................................................................................................... 3.6.2 Existing Management Plans.................................................................................................... 3.6.2.1 SLO Basin Characterization and Monitoring Well Installation ........................................ 3.6.2.2 San Luis Obispo County Master Water Report(2012).................................................... 3.6.2.3 San Luis Obispo County Integrated Regional Water Management Plan (2014)............. 3.6.2.4 City of San Luis Obispo 2015 Urban Water Management Plan(2016)........................... 3.6.3 Existing Groundwater Regulatory Programs............................................................................ 3.6.3.1 Groundwater Export Ordinance (2015).......................................................................... 3.6.3.2 Well Ordinances, County and City.................................................................................. 3.6.3.3 Countywide Water Conservation Program Resolution 2015-288 (2015) ....................... 3.6.3.4 Agricultural Order R3-2017-002 (2017).......................................................................... 3.6.3.5 Water Quality Control Plan for the Central Coast Basins (2017).................................... 3.6.3.6 California DWR Well Standards (1991)........................................................................... 3.6.3.7 Requirements for New Wells(2017)............................................................................... 3.6.3.8 Title 22 Drinking Water Program(2018)......................................................................... 3.6.3.9 Waterway Management Plan — San Luis Obispo Creek Watershed (2003).................... 3.6.3.10 Incorporation Into GSP.................................................................................................... 3.6.3.11 Limits to Operational Flexibility...................................................................................... 3.7 Conjunctive Use Programs.............................................................................................................. 3.8 Land Use Plans................................................................................................................................ 3.8.1 City of San Luis Obispo General Plan...................................................................................... 3.8.2 County of San Luis Obispo General Plan................................................................................. n Page 359 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Table of Contents 3.8.3 Los Ranchos/Edna Village Plan................................................................................................ 3.8.4 Plan Implementation Effects on Existing Land Use................................................................. 3.8.5 Plan Implementation Effects on Water Supply....................................................................... 3.8.6 Well Permitting....................................................................................................................... 3.8.7 Land Use Plans Outside of Basin............................................................................................. 3.9 Management Areas......................................................................................................................... 3.9.1 Reason for Creation................................................................................................................ 3.10 Additional GSP Elements, if Applicable........................................................................................... 4 Basin Setting (§ 354.14)......................................................................................................................... 4.1 Basin Topography and Boundaries................................................................................................. 4.2 Primary Users of Groundwater....................................................................................................... 4.3 Soils Infiltration Potential............................................................................................................... 4.4 Regional Geology............................................................................................................................ 4.4.1 Regional Geologic Structures.................................................................................................. 4.4.2 Geologic Formations within the Basin.................................................................................... 4.4.2.1 Alluvium.......................................................................................................................... 4.4.2.2 Paso Robles Formation................................................................................................... 4.4.2.3 Pismo Formation............................................................................................................. 4.4.3 Geologic Formations Surrounding the Basin.......................................................................... 4.4.3.1 Monterey Formation....................................................................................................... 4.4.3.2 Obispo Formation........................................................................................................... 4.4.3.3 Franciscan Assemblage................................................................................................... 4.5 Principal Aquifers and Aquitards.................................................................................................... 4.5.1 Cross Sections......................................................................................................................... 4.5.2 Aquifer Characteristics............................................................................................................ 4.5.3 Aquitards................................................................................................................................. 4.6 Surface Water Bodies...................................................................................................................... 4.7 Subsidence Potential....................................................................................................................... 5 Groundwater Conditions (§ 354.16)...................................................................................................... 5.1 Groundwater Elevations and Intepretation.................................................................................... 5.1.1 Fall 1954 Groundwater Elevations.......................................................................................... 5.1.2 Spring 1990 Groundwater Elevations..................................................................................... 5.1.3 Modeled 1990s Groundwater Elevations............................................................................... 5.1.4 Spring 1997 Groundwater Elevations..................................................................................... 5.1.5 Spring 2011 Groundwater Elevations..................................................................................... Page 360 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Table of Contents 5.1.6 Spring 2015 Groundwater Elevations..................................................................................... 5.1.7 Spring 2019 Groundwater Elevations..................................................................................... 5.1.8 Fall 2019 Groundwater Elevations.......................................................................................... 5.1.9 Changes in Groundwater Elevation........................................................................................ 5.1.10 Vertical Groundwater Gradients............................................................................................. 5.2 Groundwater Elevation Hydrographs............................................................................................. 5.3 Groundwater Recharge and Discharge Areas................................................................................. 5.3.1 Groundwater Recharge Areas................................................................................................. 5.3.1.1 Infiltration of Precipitation............................................................................................. 5.3.1.2 Subsurface Inflow............................................................................................................ 5.3.1.3 Percolation of Streamflow.............................................................................................. 5.3.1.4 Anthropogenic Recharge................................................................................................. 5.3.2 Groundwater Discharge Areas................................................................................................ 5.4 Change in Groundwater Storage..................................................................................................... 5.5 Seawater Intrusion.......................................................................................................................... 5.6 Subsidence...................................................................................................................................... 5.7 Interconnected Surface Water........................................................................................................ 5.7.1 Depletion of Interconnected Surface Water........................................................................... 5.8 Potential groundwater dependent ecosystems.............................................................................. 5.8.1 Hydrology................................................................................................................................ 5.8.1.1 Overview of GDE Relevant Surface and Groundwater Hydrology .................................. 5.8.1.2 Losing and Gaining Reaches............................................................................................ 5.8.2 Vegetation and Wetland Groundwater Dependent Ecosystem Identification ....................... 5.8.3 Identification of Special -Status Species and Sensitive Natural Communities Associates withGDE's.............................................................................................................................................. 5.9 Groundwater Quality Distribution and Trends............................................................................... 5.9.1 Groundwater Quality Suitability for Drinking Water.............................................................. 5.9.2 Distribution and Concentrations of Point Sources of Groundwater Constituents ................. 5.9.3 Distribution and Concentrations of Diffuse or Natural Groundwater Constituents ............... 5.9.3.1 Total Dissolved Solids...................................................................................................... 5.9.3.2 Nitrate............................................................................................................................. 5.9.3.3 Arsenic............................................................................................................................. 5.9.3.4 Boron............................................................................................................................... 5.9.3.5 Other Constituents.......................................................................................................... iv Page 361 of 1183 SLO Basin Groundwater Sustoinability Plan Table of Contents County of SLO and City of SLO 6 Water Budget (§ 354.18)....................................................................... 6.1 Climate........................................................................................... 6.1.1 Historical Climate/Base Period .............................................. 6.2 Water Budget Data Sources........................................................... 6.3 Historical Water Budget................................................................. 6.3.1 Historical Time Period............................................................ 6.3.2 Historical Land Use................................................................. 6.3.3 Historical Surface Water Budget ............................................ 6.3.4 Historical Groundwater Budget ............................................. 6.3.5 Total Groundwater in Storage ............................................... 6.3.6 Change in Storage.................................................................. 6.3.7 Sustainable Yield.................................................................... 6.3.8 Quantification of Overdraft (Historical) ................................. 6.4 Current Water Budget.................................................................... 6.5 Projected Water Budget................................................................ 6.5.1 Assumptions........................................................................... 6.5.2 Inflows.................................................................................... 6.5.3 Outflows................................................................................. 6.5.4 Change In Storage.................................................................. 6.5 Projected Water Budget................................................................................................................. 6.5.1 Assumptions............................................................................................................................ 6.5.2 Inflows..................................................................................................................................... 6.5.3 Outflows.................................................................................................................................. 6.5.4 Change In Storage................................................................................................................... 7 Monitoring Networks (§ 354.32 and § 354.34)...................................................................................... 7.1 Monitoring Objectives.................................................................................................................... 7.1.1 Management Areas................................................................................................................. 7.1.2 Representative Monitoring Sites............................................................................................ 7.1.3 Scientific Rationale.................................................................................................................. 7.1.4 Existing Monitoring Programs................................................................................................. 7.2 MONITORING NETWORKS.............................................................................................................. 7.2.1 Groundwater Level Monitoring Network............................................................................... 7.2.2 Groundwater Quality Monitoring Network............................................................................ 7.2.3 Surface Water Flow Monitoring Network............................................................................... v Page 362 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO 7.3 Sustainability Indicator Monitoring................................................................................................ 7.3.1 Chronic Lowering of Groundwater Levels............................................................................... 7.3.2 Reduction of Groundwater Storage........................................................................................ 7.3.3 Seawater Intrusion.................................................................................................................. 7.3.4 Degraded Groundwater Quality.............................................................................................. 7.3.5 Land Subsidence...................................................................................................................... 7.3.6 Depletion of Interconnected Surface Water........................................................................... 7.4 Monitoring Technical and Reporting Standards............................................................................. 7.4.1 Groundwater Levels................................................................................................................ 7.4.2 Groundwater Quality.............................................................................................................. 7.4.3 Surface Water Flow................................................................................................................. 7.4.4 Monitoring Frequency............................................................................................................ 7.5 Data Management System.............................................................................................................. 7.6 Assessment and Improvement of Monitoring Network................................................................. 7.7 Annual Reports and Periodic Evaluation by the GSAS............................................................................ 8 Sustainable Management Criteria (§ 354.22)......................................................................................2 8.1 Definitions ( § 351)........................................................................................................................3 8.2 Sustainability Goal (§ 354.24).......................................................................................................5 8.2.1 Description of Sustainability Goal.........................................................................................5 8.2.2 Sustainability Strategy...........................................................................................................5 8.3 Generalized Process For Establishing Sustainable Management Criteria (§ 354.22-30)..............6 8.4 Chronic Lowering Of Groundwater Levels Sustainability Indicator..............................................7 8.4.1 Undesirable Results (§ 354.26).............................................................................................7 8.4.1.1 Criteria for Establishing Undesirable Results §354.26(b)(2)........................................8 8.4.1.2 Potential Causes of Undesirable Results - §354.26(b)(1)..............................................9 8.4.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses - §354.26 (b)(3).....9 8.4.2 Minimum Thresholds - §354.28(c)(1)...................................................................................9 8.4.2.1 Information and Methods Used for Establishing Chronic Lowering of Groundwater Level Minimum Thresholds - §354.28(b)(1).....................................................................................9 8.4.2.2 Relationship between Individual Minimum Thresholds and Relationship to Other Sustainability Indicators - §354.28(b)(2)........................................................................................11 8.4.2.3 Effect of Minimum Thresholds on Neighboring Basins - §354.28(b)(3)......................13 8.4.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses - §354.28(b)(4) .13 8.4.2.5 Relevant Federal, State, or Local Standards - §354.28(b)(5)......................................14 8.4.2.6 Method for Quantitative Measurement of Minimum Thresholds - §354.28(b)(6) ....14 vi Page 363 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 8.4.3 Measurable Objectives - §354.30(a)-(g).............................................................................14 8.4.3.1 Information and Methods Used for Establishing Chronic Lowering of Groundwater Level Measurable Objectives §354.30(b).......................................................................................14 8.4.3.2 Interim Milestones §354.30(a)(e)...............................................................................15 8.5 Reduction of Groundwater Storage Sustainability Indicator §354.28(c)(2)...............................16 8.5.1 Undesirable Results.............................................................................................................16 8.5.1.1 Criteria for Establishing Undesirable Results §354.2(b)(2).........................................16 8.5.1.2 Potential Causes of Undesirable Results §354.2(b)(1)................................................16 8.5.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses §354.2(b)(3)........ 17 8.5.2 Minimum Thresholds §354.28(c)(2)....................................................................................17 8.5.2.1 Information and Methods Used for Establishing Reduction of Storage Minimum Thresholds §354.28(b)(1)...............................................................................................................18 8.5.2.2 Relationship between Individual Minimum Thresholds and Other Sustainability Indicators §354.28(b)(2)................................................................................................................18 8.5.2.3 Effects of Minimum Thresholds on Neighboring Basins §354.28(b)(3) ......................18 8.5.2.4 Effects of Minimum Thresholds on Beneficial Uses and Users §354.28(b)(4) ............ 19 8.5.2.5 Relation to State, Federal, or Local Standards §354.28(b)(5).....................................19 8.5.2.6 Methods for Quantitative Measurement of Minimum Threshold §354.28(b)(6) ......20 8.5.3 Measurable Objectives §354.30(a)-(g)................................................................................20 8.5.3.1 Information and Methods Used for Establishing Reduction of Groundwater Storage Measurable Objectives §354.30(b)................................................................................................20 8.5.3.2 Interim Milestones §354.30(a)(e)...............................................................................20 8.6 Seawater Intrusion Sustainability Indicator §354.28(c)(3).........................................................20 8.7 Degradation of Groundwater Quality Sustainability Indicator §354.28(c)(4) .............................20 8.7.1 Undesirable Results §354.26(a)-(d)....................................................................................20 8.7.1.1 Criteria for Establishing Undesirable Results §354.26(b)(2).......................................21 8.7.1.2 Potential Causes of Undesirable Results §354.26(b)(1)..............................................22 8.7.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses §354.26(b)(3)...... 22 8.7.2 Minimum Thresholds § 354.28(c)(4)...................................................................................22 8.7.2.1 Information and Methods Used for Establishing Degradation of Water Quality Minimum Thresholds § 354.28 (b)(1)............................................................................................22 8.7.2.2 Relation of Minimum Thresholds to Other Sustainability Indicators § 354.28(b)(2)..23 8.7.2.3 Effect of Minimum Thresholds on Neighboring Basins § 354.28(b)(3).......................24 8.7.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses § 354.28(b)(4) ..24 8.7.2.5 Relevant Federal, State, or Local Standards § 354.28(b)(5)........................................24 8.7.2.6 Method for Quantitative Measurement of Minimum Thresholds § 354.28(b)(6)......24 vii Page 364 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 8.7.3 Measurable Objectives § 354.30(a)-(g)...............................................................................24 8.7.3.1 Information and Methods Used for Establishing Degradation of Water Quality Measurable Objectives § 354.30(b)...............................................................................................25 8.7.3.2 Interim Milestones § 354.28(a)(e)..............................................................................25 8.8 Land Subsidence Sustainability Indicator § 354.28(c)(5)............................................................25 8.8.1 Undesirable Results § 354.26(a)-(d)....................................................................................25 8.8.1.1 Criteria for Establishing Undesirable Results § 354.26(b)(2)......................................26 8.8.1.2 Potential Causes of Undesirable Results § 354.26(b)(1).............................................26 8.8.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses § 354.26(b)(3).....26 8.8.2 Minimum Thresholds § 354.28(c)(5)...................................................................................26 8.8.2.1 Information and Methods Used for Establishing Land Subsidence Minimum Thresholds§ 354.28(b)(1)..............................................................................................................26 8.8.2.2 Relation of Minimum Thresholds to Other Sustainability Indicators § 354.28(b)(2)..27 8.8.2.3 Effect of Minimum Thresholds on Neighboring Basins § 354.28(b)(3).......................27 8.8.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses § 354.28(b)(4) ..27 8.8.2.5 Relevant Federal, State, or Local Standard § 354.28(b)(5)......................................... 27 8.8.2.6 Method for Quantitative Measurement of Minimum Thresholds § 354.28(b)(6)......27 8.8.3 Measurable Objectives § 354.30(a)-(g)...............................................................................28 8.8.3.1 Information and Methods Used for Establishing Land Subsidence Measurable Objectives 0§ 354.3(b)................................................................................................................... 28 8.8.3.2 Interim Milestones § 354.28(a)(e)..............................................................................28 8.9 Depletion of interconnected surface water Sustainability Indicator § 354.28(c)(6) ..................28 8.9.1 Undesirable Results § 354.26(a)-(d)....................................................................................28 8.9.1.1 Criteria for Establishing Undesirable Results § 354.26(b)(2)......................................29 8.9.1.2 Potential Causes of Undesirable Results § 354.26(b)(1).............................................29 8.9.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses § 354.26(b)(3).....29 8.9.2 Minimum Thresholds..........................................................................................................29 8.9.2.1 Information and Methods Used for Establishing Depletion of Interconnected Surface Water Minimum Thresholds..........................................................................................................30 8.9.2.2 Relationship between Individual Minimum Thresholds and Other Sustainability Indicators 31 8.9.2.3 Effects of Minimum Thresholds on Neighboring Basins ................. 8.9.2.4 Effects of Minimum Thresholds on Beneficial Uses and Users....... 8.9.2.5 Relation to State, Federal, or Local Standards ................................ 8.9.2.6 Methods for Quantitative Measurement of Minimum Threshold . 8.9.3 Measurable Objectives........................................................................... ........................ 31 ........................ 32 ........................ 32 ........................ 32 ........................ 32 Page 365 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO Table of Contents 8.9.3.1 Method for Quantitative Measurement of Measurable Objectives ...........................33 8.9.3.2 Interim Milestones......................................................................................................33 8.10 Management Areas.....................................................................................................................33 9 Projects and Management Actions (§ 354.44)....................................................................................... 9.1 Projects........................................................................................................................................... 9.1.1 Project A.................................................................................................................................. 9.2 Management Actions...................................................................................................................... 9.2.1 Management Action A............................................................................................................ 9.3 Projects Needed to Mitigate Overdraft.......................................................................................... 10 Implementation Plan.............................................................................................................................. 10.1 Cost of Implementation.................................................................................................................. 10.2 Funding Alternatives....................................................................................................................... 10.3 Implementation Schedule............................................................................................................... 10.4 GSP Annual Reporting..................................................................................................................... 10.5 Periodic Evaluations of GSP............................................................................................................ 11 Notice and Communications (§ 354.10)................................................................................................. 11.1 Communications and Engagement Plan......................................................................................... 11.2 Nature of Consultations.................................................................................................................. 11.3 Public Meetings............................................................................................................................... 11.4 Incorporation of Feedback in Decision -Making Process................................................................. 11.5 Comments Received....................................................................................................................... 11.6 Responses to Comments................................................................................................................. 12 Interagency Agreements (§ 357.2-4)..................................................................................................... 12.1 Coordination Agreements............................................................................................................... 13 References.............................................................................................................................................. 14 Appendices............................................................................................................................................. The grey highlighted sections in the Table of Contents (TOC) indicate that the section has been previously released (Chapters 1 through 7) or will be released in the future (Chapters 9 through 14). The complete list of the anticipated TOC is presented to give the reader context as to how Chapter 8 — Sustainable Management Criteria, connects with the complete Groundwater Sustainability Plan. ix Page 366 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO LIST OF FIGURES List of Figures Figure 8-1 HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-19...... 34 Figure 8-2 HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-16...... 34 Figure 8-3. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-09....35 Figure 8-4. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-12....35 Figure 8-5. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-12...... 36 Figure 8-6. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-04...... 36 Figure 8-7. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-09...... 37 Figure 8-8. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-16...... 37 Figure 8-9. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-01...... 38 Figure 8-10. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-11...38 x Page 367 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO TABLES No table of figures entries found. Tables xi Page 368 of 1183 SLO Basin Groundwater Sustoinability Plan County of SLO and City of SLO APPENDICES Appendices Appendix A - City of San Luis Obispo Resolution to form GSA Appendix B - County of San Luis Obispo Resolution to form GSA Appendix C - Memorandum of Agreement — Preparation of GSP Appendix D Communications and Engagement Plan Appendix E Surface Water/Groundwater Modeling Approach Appendix F Stakeholder Workshop Summary — Building a Shared Vision for a "Sustainable SLO Basin" Appendix G Sustainable Goal Setting Workshop Appendix H Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin Appendix I Groundwater Level Measurement Procedures for the San Luis Obispo Valley Groundwater Basin GSP Appendix J Streamflow Measurement in Natural Channels Appendix K Data Management Plan Appendix L Response to Public Comments xn Page 369 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet MCL Maximum Contaminant Level xiii Page 370 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo County Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant xiv Page 371 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is complete. Executive Summary Page 372 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8 SUSTAINABLE MANAGEMENT CRITERIA (§ 354.22) This chapter defines the conditions specified at each of the Representative Monitoring Sites (RMSs) that constitute Sustainable Management Criteria (SMCs), discusses the process by which the GSAs in the Basin will characterize undesirable results, and establishes minimum thresholds and measurable objectives for each Sustainability Indicator. The chapter defines Sustainability in the Basin for the purposes of managing groundwater in compliance with SGMA, and it addresses the regulatory requirements involved. The Measurable Objectives (MOs), Minimum Thresholds (MTs), and undesirable results presented in this chapter define the future sustainable conditions in the Basin and guide the GSAs in development of policies, implementation of projects, and promulgation of management actions that will achieve these future conditions. Defining Sustainable Management Criteria (SMC) requires technical analysis of historical data, and input from the affected stakeholders in the Basin. This chapter presents the data and methods used to develop the SMC and demonstrate how they influence beneficial uses and users. The SMCs presented in this chapter are based on currently available data and application of the best available science. As noted in this GSP, data gaps exist in the hydrogeologic conceptual model. Uncertainty caused by these data gaps was considered when developing the SMC. Due to uncertainty in the hydrogeologic conceptual model, these SMCs are considered initial criteria and will be reevaluated and potentially modified in the future as new data become available. The discussion of SMC in this chapter is organized by Sustainability Indicators. The following Sustainability Indicators are applicable in the Basin: • Chronic lowering of groundwater elevations • Reduction in groundwater storage • Degraded water quality • Land subsidence • Depletion of interconnected surface water The sixth Sustainability Indicator, sea water intrusion, only applies to coastal basins, and is not applicable in the Basin. To maintain an organized approach throughout the text, this chapter follows the same structure for each Sustainability Indicator. The description of each SMC contains all the information required by Section 354.22 et. seq of the SGMA regulations and outlined in the Sustainable Management Criteria BMP (DWR, 2017), including: How undesirable results were developed, including: o The criteria defining when and where the effects of the groundwater conditions that cause undesirable results based on a quantitative description of the combination of minimum threshold exceedances (§354.26 (b)(2)) o The potential causes of undesirable results (§354.26 (b)(1)) o The effects of these undesirable results on the beneficial users and uses (§354.26 (b)(3)) How minimum thresholds were developed, including: o The information and methodology used to develop minimum thresholds (§354.28 (b)(1)) o The relationship between minimum thresholds and the relationship of these minimum thresholds to other Sustainability Indicators (§354.28 (b)(2)) o The effect of minimum thresholds on neighboring basins (§354.28 (b)(3)) o The effect of minimum thresholds on beneficial uses and users (§354.28 (b)(4)) 2 Page 373 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO o How minimum thresholds relate to relevant Federal, State, or local standards (§354.28 (b)(5)) o The method for quantitatively measuring minimum thresholds (§354.28 (b)(6)) How measurable objectives were developed, including: o The methodology for setting measurable objectives (§354.30) o Interim milestones (§354.30 (a), §354.30 (e), §354.34 (g)(3)) The SGMA regulations address minimum thresholds before measurable objectives. This order was maintained for the discussion of all applicable Sustainability Indicators. 8.1 DEFINITIONS (§ 351) The SGMA legislation and regulations contain a number of new terms relevant to the SMCs. These terms are defined below using the definitions included in the SGMA regulations (§ 351, Article 2). Where appropriate, additional explanatory text is added in italics. This explanatory text is not part of the official definitions of these terms. To the extent possible, plain language, including limited use of overly technical terms and acronyms, was used so that a broad audience will understand the development process and implications of the SMCs. 1. Interconnected surface water (ISW) refers to surface water that is hydraulically connected at any point by a continuous saturated zone between the underlying aquifer and the overlying surface water. Interconnected surface waters are parts of streams, lakes, or wetlands where the groundwater table is at or near the ground surface and there is water in the lakes, streams, or wetlands. 2. Interim milestone (IM) refers to a target value representing measurable groundwater conditions, in increments of five years, set by an Agency as part of a Plan. Interim milestones are targets such as groundwater elevations that will be achieved every five years to demonstrate progress towards Sustainability. 3. Management area refers to an area within a basin for which the Plan may identify different minimum thresholds, measurable objectives, monitoring, or projects and management actions based on differences in water use sector, water source type, geology, aquifer characteristics, or other factors. 4. Measurable objectives (MOs) refer to specific, quantifiable goals for the maintenance or improvement of specified groundwater conditions that have been included in an adopted Plan to achieve the sustainability goal for the basin. Measurable objectives are goals that the GSP is designed to achieve. 5. Minimum thresholds (MTs) refer to numeric values for each Sustainability Indicator used to define undesirable results. Minimum thresholds are established at representative monitoring sites. Minimum thresholds are indicators of where an unreasonable condition might occur. For example, a particular groundwater elevation might be a minimum threshold if lower groundwater elevations would result in a significant and unreasonable reduction in groundwater storage. 6. Representative monitoring site (RMS) refers to a monitoring site within a broader network of sites that typifies one or more conditions within the basin or an area of the basin. 7. Sustainability Indicator refers to any of the effects caused by groundwater conditions occurring throughout the basin that, when significant and unreasonable, cause undesirable results, as described in Water Code Section 10721(x). The five Sustainability Indicators relevant to the Basin are listed in the introductory section of Chapter 8. 8. Uncertainty refers to a lack of understanding of the basin setting that significantly affects an Agency's ability to develop sustainable management criteria and appropriate projects and management actions in a Plan, or to evaluate the efficacy of Plan implementation, and therefore may limit the ability to assess whether a basin is being sustainably managed. 3 Page 374 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Undesirable Result Section 10721 of the Sustainable Groundwater Management Act states that Undesirable result means one or more of the following effects caused by groundwater conditions occurring throughout the basin: a. Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods. b. Significant and unreasonable reduction of groundwater storage. c. Significant and unreasonable seawater intrusion. d. Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies. e. Significant and unreasonable land subsidence that substantially interferes with surface land uses. f. Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water. 10. Section § 354.26 of the SGMA regulations states that "The criteria used to define when and where the effects of the groundwater conditions cause undesirable results shall be based on a quantitative description of the combination of minimum threshold exceedances that cause significant and unreasonable effects in the basin." 521 Page 375 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.2 SUSTAINABILITY GOAL (§ 354.24) The sustainability goal for the San Luis Obispo Basin is a comprehensive statement that describes the important factors to be considered during the SGMA planning horizon. The Sustainability goal was developed over a series of public meetings and public workshops with input from the City, County, and affected stakeholders. The June 10, 2020 Stakeholder Workshop, Groundwater Management Vision, was dedicated to obtaining information to be used to develop a sustainability goal for the Basin. In the workshop, stakeholders participated in an interactive visioning exercise where they helped populate a virtual white board to answer the question, "What is our shared vision of what a 'sustainable SLO Basin' means?" Stakeholders added ideas, perceptions, outcomes, and values onto the white board across the following categories: • Available Groundwater Supply: What needs/uses does our groundwater supply always need to be able to serve? • Available Groundwater Storage: What needs/uses does our stored groundwater need to serve or prepare us for? • Groundwater Dependent Ecosystem Health: What outcomes do we want for surface water ecosystems and prevention of land subsidence? • Cost to Users: If we achieve a "sustainable Basin," how does it look to ratepayers? • Groundwater Quality: What is the quality of groundwater we aim to sustain? During the September 9, 2020 GSC meeting, the results of the interactive exercise from the June workshop were presented in an organized fashion to stakeholders. Significant concepts from the visioning exercise are incorporated into the Sustainability Goal presented herein and are represented as guiding principles that underpin the Basin Sustainability goal. The SGMA regulations require the sustainability goal to culminate in the absence of undesirable results within 20 years of the applicable statutory deadline. Per Section § 354.24 of the SGMA regulations the Sustainability goal has three parts: • Description of the Sustainability goal • A discussion of the measures that will be implemented to ensure the Basin will be operated within sustainable yield, and • An explanation of how the Sustainability goal is likely to be achieved. 8.2.1 Description of Sustainability Goal The Sustainability goal for the Basin is to manage the Basin to ensure beneficial uses and basin users have access to a safe and reliable groundwater supply that meets current and future demand without causing undesirable results. Guiding principles of this goal are: • Available groundwater supply supports diverse needs reliably and equitably. • Stored groundwater equitably supports supply resilience and evolving needs. • Groundwater levels support the sustained health of groundwater dependent ecosystems. • Cost of maintaining sustainable groundwater levels is equitably distributed. • Groundwater quality is maintained to a safe standard to meet diverse basin needs. 8.2.2 Sustainability Strategy 5 Page 376 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO The sustainability strategy will be developed and discussed at the upcoming GSC meetings. This section will include a discussion of the measures that will be implemented to ensure the basin will be operated within the sustainable yield, to be completed after Chapter 9 -Projects and Management Actions is approved and will be included in the Public Draft of the GSP, and an explanation of how the sustainability goal is likely to be achieved, to be completed after Chapter 10 -Implementation Plan is approved and will be included in the Public Draft of the GSP. 8.3 GENERALIZED PROCESS FOR ESTABLISHING SUSTAINABLE MANAGEMENT CRITERIA (§ 354.22-30) SMCs for the Basin were developed after technical analysis of hydrogeologic and geotechnical data by the consulting team, input from the GSC members, public input received in public meetings, written public comments in response to GSC meeting and workshop presentations, and meetings with GSA staff and GSC members. Public comments on alternative SMCs discussed during GSC meetings and responses to those comments are included in Appendix M. All presentations made at public meetings are available for review at the SLO Basin web site created for this GSP, www.slowaterbasin.com. The process further built on the Basin Groundwater Sustainability Agencies' history of involving interested parties — including the City, the County, environmental stakeholders, rural residents, agricultural stakeholders, water purveyors, and mutual water companies — in public meetings focused on groundwater resource planning. The general process for establishing minimum thresholds and measurable objectives for the SMC and assessing significant and unreasonable conditions constituting undesirable results in the Basin was iterative and included the following: • Evaluating historical data on groundwater elevations from wells monitored by the City and County. • Evaluating water budget information presented in Chapter 6, including sustainable yield estimates and average deficits for the San Luis Valley and Edna Valley parts of the basin. • Holding a series of public outreach meetings that outlined the GSP development process and introduced stakeholders to SMC, MOs, MTs, and other related information. • Soliciting public comment and input on several alternative minimum threshold and measurable options based upon preliminary technical analysis presented at GSC meetings. • Evaluating public comment to assess what are significant and unreasonable effects relevant to SMC. Public comments from outreach meetings was analyzed to assess if different areas in the Basin had different perspectives for what constitutes an undesirable result in the Basin and how minimum thresholds and measurable objectives are established. • Combining public comment, outreach efforts, hydrogeologic data and considering the interests of beneficial uses and groundwater users, land uses, and property interests in the Basin to describe undesirable results and setting preliminary conceptual MTs and MOs. • Performing groundwater model simulations that incorporate projects and management actions discussed in Chapter 9 to assess if the SMC are achievable. • Conducting public meetings to present recommended preliminary conceptual minimum thresholds and measurable objectives and receiving additional public input. Presentations and discussion of SMCs occurred at eleven meetings in the Basin between March 2020 and May 2021. • Reviewing and considering public and GSC input on recommended preliminary SMCs with GSA staff. • GSC recommended final SMCs to GSAs for approval. A number of alternative options for both MTs and MOs were considered for each RMS after evaluation of the historical record of groundwater elevations at each well, assessment of trends of groundwater elevation decline (where applicable), and input from stakeholders regarding their desired conditions. 151 Page 377 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Details regarding the specific SMCs for each Sustainability Indicator are included in the following sections of this chapter describing each indicator. For all applicable Sustainability Indicators except for water quality (Le., chronic lowering of groundwater levels, reduction of storage, land subsidence, and depletion of interconnected surface water), this GSP uses water levels as a proxy measurement metric to assess the SMCs for each indicator. Water levels are measured directly at each RMS. For the land subsidence Sustainability Indicator, direct measurement of changes in land surface elevation data (InSAR data) published by DWR define the SMCs, and water levels will be monitored in an RMS in the area of documented past subsidence to monitor groundwater conditions (SLV-09), and to manage such that water levels do not approach the levels observed in 1991- 1992. 8.4 CHRONIC LOWERING OF GROUNDWATER LEVELS SUSTAINABILITY INDICATOR This section of the GSP describes the SMC for the Chronic Lowering of Groundwater Levels Sustainability Indicator. The definition of Undesirable Results is presented, and MTs and MOs are presented for each RMS in the monitoring network. 8.4.1 Undesirable Results (§ 354.26) The definition of undesired conditions for the Chronic Lowering of Groundwater Indicator for the purposes of this GSP is as follows: The Basin will be considered to have undesirable results if two or more RMSs for water levels within a defined area of the Basin (i.e., San Luis Valley or Edna Valley) display exceedances of the minimum threshold groundwater elevation values for two consecutive fall measurements. Geographically isolated exceedances (i.e., conditions in a single well) will require investigation to determine if local or basin wide actions are required in response. Details addressing specific MTs and MOs are presented in the following sections. A summary of MTs and MOs used in the definition of Undesirable Conditions for the Chronic Lowering of Groundwater Sustainability Indicator are presented along with other indicators in Table 8-1. VA Page 378 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Table 8-1 . Summary of MTs, MOs, and IMs for SLO Basin RMSs. • 2020 WL 2027• •Indicator San Luis Valley SLV-09 102 110 119 110 110 110 Subsidence/Water Levels SLV-16 SLV-19 SLV-12 70 80 85 100 110 100 111 123 107 100 110 100 100 110 100 100 110 100 Water Levels/Storage Water Levels/Storage SW-GW Interaction/Water Levels Edna Valley EV-09 82 164 146 150 155 160 Water Levels/Storage EV-04 160 247 209 219 229 239 Water Levels/Storage EV-13 172 248 215 223 231 238 Water Levels/Storage EV-16 150 190 180 175 180 185 Water Levels/Storage EV-01 263 314 290 314 314 314 SW-GW Interaction /Water levels EV-11 177 227 219 227 227 227 SW-GW Interaction /Water levels Note: All water level and interim milestone measurements refer to fall measurements. 8.4.1.1 Criteria for Establishing Undesirable Results §354.26(b)(2) Significant and unreasonable Chronic Lowering of Groundwater Levels in the Basin are those that: • Reduce the ability of existing domestic wells of average depth to produce adequate water for domestic purposes (drought resilience). • Cause significant financial burden to those who rely on the groundwater basin. • Interfere with other SGMA Sustainability Indicators. .91 Page 379 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.4.1.2 Potential Causes of Undesirable Results - §354.26(b)(1) Conditions that could theoretically lead to an undesirable result include the following: Continuation of current levels of Edna Valley pumpage without development of additional water supply projects, or development of additional municipal or agricultural pumping at significantly higher rates than are currently practiced. Maintenance of current or additional non -de minimis pumping may result in continued decline in groundwater elevations and exceedance of the proxy minimum threshold. Expansion of de minimis pumping. Adding domestic de minimis pumpers in the areas of the Basin administered by the County may result in lower groundwater elevations, and an exceedance of the proxy minimum threshold. Extensive, unanticipated drought. Minimum thresholds are established based on reasonable anticipated future climatic conditions. Extensive, unanticipated droughts more severe than those on record may lead to excessively low groundwater recharge and unanticipated high pumping rates that could cause an exceedance of the proxy minimum threshold. 8.4.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses - §354.26 (b)(3) The primary effects on the beneficial users occurs from allowing multiple exceedances of the MTs in a small geographic area. Allowing two exceedances in a network of 10 RMS wells is reasonable if the exceedances are distributed throughout the Basin. If the exceedances are clustered in a limited area, it indicates that significant unreasonable effects are being experienced by a localized group of landowners. Any exceedances will require investigation to determine the significance and causes of the observed conditions. 8.4.2 Minimum Thresholds - §354.28(c)(1) Section §354.28(c)(1) of the SGMA regulations states that "The minimum threshold for chronic lowering of groundwater levels shall be the groundwater elevation indicating a depletion of supply at a given location that may lead to undesirable results". After the 10 RMS had been selected and discussed at public meetings, numerous alternative draft MTs were developed based on the evaluation of historical groundwater elevations over the available period of record (including consideration of average water levels over various time periods, long term trends, response to the recent drought, etc.), consideration of likely future use of groundwater, well construction data, assessment of remaining available saturated thickness, and public input from stakeholders. The following sections present details on the development of MTs for specific RMSs in the Basin. 8.4.2.1 Information and Methods Used for Establishing Chronic Lowering of Groundwater Level Minimum Thresholds - §354.28(b)(1) The primary source of data that was evaluated for the Sustainability Indicator of chronic lowering of groundwater levels is historical groundwater elevation data collected by the County. The information used for establishing the MOs and MTs for the chronic lowering of groundwater levels Sustainability Indicator included: • Historical groundwater elevation data from wells monitored by the County of San Luis Obispo. • Depths and locations of existing wells. • Maps of current and historical groundwater elevation data. • Input from stakeholders regarding significant and unreasonable conditions and desired current and future groundwater elevations communicated during public meetings and solicitation of public comment on various options of MTs and MOs presented in the public forum. • Results of modeling of various project scenarios of future groundwater level conditions. It is observed that historical trends of water levels are significantly different in the San Luis Valley and the Edna Valley. For this reason, the approach for setting MTs is different in the San Luis Valley than in the Edna Valley. Q Page 380 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO San Luis Valley In the San Luis Valley, there have been no long-term water level declines in any of the monitoring wells or RMS (Figure 5-11). All four of the RMS hydrographs in San Luis Valley (SLV-09, SLV-12, SLV-16, and SLV-19) display a significant temporary decline in water levels in the early 1990s. This corresponds to the period when the City increased pumping from their wells during the drought of the late 1980s and early 1990s. After 1992-1993, the City reduced pumping and water levels have been in relative equilibrium since seasonal fluctuations continue, but water levels have been essentially stable. However, City staff and City GSA participants have communicated their desire to maintain flexibility to develop groundwater in the future to potentially augment their water supply portfolio to supply the public with drinking water in their service area. Therefore, the City wishes to avoid the definition of MTs that would prevent this. For this reason, MTs in the San Luis Valley are set 10 to 20 feet lower than previously observed low water levels, to allow for potential future groundwater development by the City. The GSAs will coordinate during GSP implementation to ensure such future development does not lead to undesirable results in the Basin. The GSAs considered historical groundwater elevations, available saturated thickness, proximity of nearby wells, and general hydrogeologic judgement when setting these MTs. Figure 7-1 displays the locations of representative wells in the Basin. MTs are presented in Table 8-1. Figures 8-1 through 8-4 present historically observed water levels in the four RMS in the San Luis Valley portion of the basin, and the MTs set at these wells. Edna Valley In Edna Valley, by contrast, four wells show water level declines over the past 20-30 years (EV-04, EV-09, EV-12, and EV-16). Various alternative approaches were considered to establish MTs including designation of current water levels, water levels higher than current water levels, historical low water levels (usually those that occurred in 2015 at the end of the recent drought), and levels lower than the historical low. Not all of the Edna Valley hydrographs show the same trends. Each hydrograph has unique characteristics depending on the local hydrogeologic setting in the immediate vicinity of the well, and this leads to the consideration of different definitions of MTs for different wells, as discussed below. RMS EV-12, EV-04, and EV-09 display declining water levels over the past 20-25 years, with historical low elevations occurring around Fall 2015 at the end of the recent drought. The hydrographs for all three of these wells display recovery of water levels since then (Figures 8-5, 8-6, 8-7). Agricultural stakeholders in the Edna Valley communicated concern that setting the MT at the 2015 water levels in these wells would not provide them adequate operational flexibility to protect their long investments in the production of agriculture in the area. At the April 7, 2021 GSC meeting they requested consideration of an MT for these three RMSs to be defined 10 feet lower than 2015 drought water level. They communicated their desire for a slightly greater factor of safety for their operations and investments in the event of another drought during the planning horizon of SGMA activities. Members of the GSC were polled, and a majority of the GSC members agreed that this was a reasonable request to protect the significant investments in vineyard agriculture in the valley, and would not be considered an undesirable condition in this part of Edna Valley. Therefore, for these three wells, the MTs were defined to be 10 feet lower than the historical low groundwater elevation observed in 2015, at the height of the recent drought. (The measurement for EV-04 represents the Spring 2015 measurement; the Fall measurement was not collected. It is assumed that the Fall measurement would be lower than the Spring measurement, so the MT is set slightly lower than the Spring measurement.) In order to assess the risk of having groundwater elevations lower than recent drought low levels, an analysis was performed to evaluate potential water level of MTs compared to the depths of private domestic wells identified in County data. The basin -wide Fall 2015 groundwater elevations were mapped and compared to the total depths of domestic wells in the County's well permitting database. Then the 10 Page 381 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 2015 groundwater elevation arrays were reduced by 25 feet, and then 50 feet, to project conditions of lowered water levels. These revised lowered groundwater elevations were then compared to the total depths of the identified domestic wells. If in any of these comparison evaluations, the water level was below the total depth of a domestic well, that well was marked as "dry" in the analysis. The objective of this analysis is to assess the level of impact to domestic wells associated with water level reduction of these magnitudes. This is not intended to be a definitive analysis, given that depth and location data of the domestic wells are imperfect (many wells in the database are placed on the same point location, an artifact of the practice of assigning locations to the center of a section if better information is not available.) However, it is intended to provide a general indication of how many additional domestic wells might be impacted if water levels were decreased. For the analysis of 2015 water levels, the data indicated 15 wells as "dry". (In reality, anecdotal information indicates knowledge of four known wells that needed to be replaced or stopped being used during the drought in Edna Valley). For water levels 25 feet lower than 2015 water levels, 29 wells were identified as "dry". For water levels 50 feet lower than 2015 water levels, 40 wells were identified as "dry". This evaluation was performed to give a relative idea as to the potential impact on domestic wells of lowered water levels. The conclusion of this analysis was that water levels 25 feet and 50 feet lower than the drought minimums would result in an unacceptable condition in which the number of domestic supply wells at risk of adverse operating conditions was too high. Afterward, an additional iteration of this analysis was performed in which water levels 10 feet lower than the 2015 water levels were assessed. At 10 feet of groundwater elevation reduction, no domestic wells in the County database were indicated as "dry", beyond those identified as dry using 2015 water levels. Therefore, the conclusion of this analysis is that lowering water levels 25 to 50 feet below 2015 conditions constitutes an unreasonable risk to domestic well owners, but that water levels 10 feet below the 2015 drought levels constitutes an acceptable level of risk for all stakeholders, and the definition of MTs for wells in this area 10 feet lower than 2015 levels does not constitute unreasonable or undesirable conditions. RMS EV-16 displays a relatively steady decline in water levels of about 3.25 feet/year at the Varian Ranch Mutual Water Company (VRMWC) service area since the year 2000. The 2011-2015 drought is not apparent in this hydrograph as a period of historical low groundwater elevations. For this well, the MT was set at an elevation of 150 feet, lower than current groundwater elevations of about 180 feet, to allow for the various mutual water companies in the area to implement projects to slow and stabilize the observed water level declines (Figure 8-10). Consideration of the recent rate of groundwater elevation decline, amount of available saturated thickness, and hydrogeologic judgement regarding the amount of time likely required to mitigate this trend, were used in defining the MTs at this well. (VRMWC owns property and wells in the adjacent Arroyo Grande sub -basin of the Santa Maria Valley Groundwater Basin, which may be useful in reversing this trend, and will be discussed in Chapter 9.) 8.4.2.2 Relationship between Individual Minimum Thresholds and Relationship to Other Sustainability Indicators - §354.28(b)(2) Section 354.28 of the SGMA regulations requires that the description of all MTs include a discussion of the relationship between the MTs for each Sustainability Indicator. In the SMC Best Management Practices document (DWR, 2017), DWR has clarified this requirement. First, the GSP must describe the relationship between each Sustainability Indicator's MT by describing why or how a water level MT set at a particular RMS is similar to or different to water level thresholds in a nearby RMS. Second, the GSP must describe the relationship between the selected MT and MTs for other Sustainability Indicators; in other words, describe how (for example) a water level minimum threshold would not trigger an undesirable result for land subsidence. 11 Page 382 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Groundwater elevation MTs are derived from examination of the historical record reflected in hydrographs at the RMS. They were tested for achievability through model simulations (as described in Chapter 9). Because the MOs are largely based on observed historical groundwater conditions, the minimum thresholds derived from these objectives are not expected to conflict with each other. Groundwater elevation MTs can theoretically influence other Sustainability Indicators. Examples are listed below: 1. Change in groundwater storage. Changes in groundwater elevations are directly correlated to changes in the amount of stored groundwater. Pumping at or less than the sustainable yield will maintain or raise average groundwater elevations in the Basin. The groundwater elevation MTs are set to establish a minimum elevation that will not lead to undesirable conditions, and that are acceptable to the stakeholders in the area. Therefore, if the groundwater elevation MTs are met, they will not result in long term significant or unreasonable changes in groundwater storage. 2. Subsidence. A significant and unreasonable condition for subsidence is permanent pumping - induced subsidence that substantially interferes with surface land use. One cause for subsidence is dewatering and compaction of clay -or peat -rich sediments in response to lowered groundwater levels. As discussed in Chapter 5, significant subsidence was observed along Los Osos Valley Road in the early 1990s, which resulted in the City paying significant damages to affected local businesses. No observed subsidence has been reported in the Edna Valley. If MTs are maintained higher than the historically low water levels that were observed during the subsidence episode, this will minimize the risk of additional subsidence in the Basin. The groundwater elevation MT in RMS SLV- 09 along Los Osos Valley Road is set 15 feet higher than the historically low groundwater elevation observed in the early 1990s. Therefore, if this MT is met, it should minimize the risk of further subsidence along Los Osos Valley Road. No subsidence MTs based on water levels are established in Edna Valley (the actual MTs for subsidence will be based on InSAR data provided annually by DWR, and are discussed later in this chapter). Should new subsidence be observed due to lower groundwater elevations, the groundwater elevation MTs will be raised to mitigate this subsidence and avoid future subsidence. 3. Degraded water quality. Protecting groundwater quality is critically important to all groundwater users in the Basin, particularly for drinking water and agricultural uses. Maintaining groundwater levels protects against degradation of water quality or exceeding regulatory limits for constituents of concern in supply wells due to actions proposed in the GSP. Water quality in the Basin could theoretically be affected through two processes: a. Low groundwater elevations in an area could theoretically cause deeper, poorer -quality groundwater to flow upward from bedrock into existing supply wells. Should groundwater quality degrade due to lowered groundwater elevations, the groundwater elevation MTs may be raised to avoid this degradation. However, since MTs are set to avoid significant declines of groundwater elevations below historically observed levels, and the historical low water levels did not result in water quality degradation, this is not expected to occur. b. Changes in groundwater elevation due to actions implemented to achieve sustainability could change groundwater gradients, which could cause poor quality groundwater to flow towards supply wells that would not have otherwise been impacted. However, MTs are established so as not to change the basin patterns or gradients of groundwater flow, so this is not expected to occur in the Basin. 4. Depletion of Interconnected Surface Water. Groundwater levels measured at representative monitoring wells (SLV-12, EV-01, EV-11) will serve as a proxy for depletion of interconnected surface water. In addition, stream flow gages along SLO Creek will continue to measure surface water conditions in San Luis Valley, and proposed stream gages along Corral de Piedras Creek will serve to generate information on surface water inflow and outflow in Edna Valley, allowing for direct measurement of surface water gains and losses to the groundwater systems based on future hydrologic and pumping conditions in the Basin. However, MTs along the Creeks are defined at 12 Page 383 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO levels designed to avoid significant water declines in these areas, with the goal of minimizing any potential significant depletion of interconnected surface water flows. 5. Seawater intrusion. This Sustainability Indicator is not applicable to this Groundwater Basin. 8.4.2.3 Effect of Minimum Thresholds on Neighboring Basins - §354.28(b)(3) Two neighboring groundwater basins share a boundary with the San Luis Obispo Basin; the Los Osos Basin to the northwest, and the Arroyo Grande Subbasin of the Santa Maria Valley Groundwater Basin to the southeast. The shared boundary with both of these basins is not extensive, and the Hydrogeologic Conceptual Model (HCM) posits that a groundwater divide separates the groundwater between those basins and the San Luis Obispo Basin. In the San Luis Valley there have been no trends indicating groundwater declines that would affect the Los Osos Basin. In Edna Valley the areas with observed declines are over two miles downgradient from the Arroyo Grande Subbasin boundary. It is not anticipated that actions associated with the GSP will have any significant impact on either the Los Osos Basin or the Arroyo Grande Subbasin. Additionally, the SLO Basin GSAs have developed a cooperative working relationship with both the Los Osos Groundwater Basin — Basin Management Committee and the GSAs working in the Arroyo Grande Subbasin. Hydrogeologic conditions near the basin boundaries will be monitored, and any issues potentially affecting those basins will be communicated. 8.4.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses - §354.28(b)(4) Agricultural land uses and users The agricultural stakeholders in the Edna Valley have maintained an active role during the development of this GSP. The groundwater elevation MTs place a practical limit on the acceptable lowering of groundwater levels in the Basin, thus conceptually restricting the current level of agriculture in the region without projects to supplement water supply to the Basin, or management actions to reduce current pumping. In the absence of other mitigating measures, this has been the practical effect of potentially limiting the amount of groundwater pumping in the Basin. Limiting the amount of groundwater pumping could limit the additional amount and type of crops that can be grown in the Basin, which could result in a reduction of economic viability for some properties. The groundwater elevation MTs could therefore limit the Basin's agricultural economy. This could have various effects on beneficial users and land uses: • There could be an economic impact to agricultural employees and suppliers of agricultural production products and materials, as well as the tourism industry supported by the wineries in the Basin. Many parts of the local economy rely on a vibrant agricultural industry and they too will be hurt proportional to the losses imparted to agricultural businesses. • Growth of city, county, and state tax rolls could be slowed or reduced due to the limitations imposed on agricultural growth and associated activities. However, it should be noted that projects and management actions discussed in Chapter 9 will be pursued to allow for alternatives to reductions in agricultural pumping. Urban land uses and users The groundwater elevation MTs effectively limit the amount of groundwater pumping in the Basin. However, the MTs in the San Luis Valley are established below currently observed groundwater elevations to allow for reasonable future development of groundwater for potable supply to City residents. If groundwater elevations decline in the immediate vicinity of SLO Creek, this could potentially result in less groundwater discharge to the creek due to areas of interconnected groundwater and surface water. 13 Page 384 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Impacts to stream flows will be monitored with the augmentation of current data collection programs in San Luis Valley, and the addition of new stream gauges in the Basin. Domestic land uses and users The groundwater elevation MTs are established to protect as many domestic wells as possible. Therefore, the MTs will likely have an overall beneficial effect on existing domestic land uses by protecting the ability to pump from domestic wells within the Edna Valley portion of the Basin. However, limited saturated thickness in some localized areas in the Basin of the shallowest domestic wells may require owners to drill deeper wells if water levels are decreased. Additionally, the groundwater elevation MTs may limit the increase of non -de minimis groundwater use in order to limit future declines in groundwater levels caused by non -de minimis domestic pumping. Ecological land uses and users Groundwater elevation MTs protect the groundwater resource and the existing ecological habitats that rely upon it because they are set to avoid long term declines in groundwater levels. As noted above, groundwater level MTs may limit increases in non -de minimis and agricultural groundwater uses. Ecological land uses and users may benefit by this reduction in non -de minimis and agricultural groundwater uses. 8.4.2.5 Relevant Federal, State, or Local Standards - §354.28(b)(5) No Federal, State, or local standards exist for chronic lowering of groundwater elevations. 8.4.2.6 Method for Quantitative Measurement of Minimum Thresholds - §354.28(b)(6) Conformance of Basin conditions to the established groundwater elevation MTs will be assessed through direct measurement of water levels from existing RMS. During planned 5-year revisions to this GSP, additional RMS may be stablished for the SMC evaluations, and direct water level measurements at these wells will be the method for quantitative measurement of MTs in the future. Groundwater level monitoring will be conducted in accordance with the monitoring plan outlined in Chapter 7 and will comply with the requirements of the technical and reporting standards included in SGMA regulations. As noted in Chapter 7, the existing groundwater monitoring network in the Basin includes 12 wells. The GSP monitoring network developed in Chapter 7 increases the groundwater monitoring network to 40 wells to be used for water level measurements. 8.4.3 Measurable Objectives - §354.30(a)-(g) The MOs for chronic lowering of groundwater levels represent target groundwater elevations that are established to achieve the sustainability goal by 2042. MOs are groundwater levels established at each RMS. MO groundwater levels are higher than MT groundwater levels, and provide operational flexibility above MTs to ensure that the Basin be sustainably managed over a range of climate and hydrologic variability. MOs are subject to change by the GSAs after GSP adoption as new information and hydrologic data become available. 8.4.3.1 Information and Methods Used for Establishing Chronic Lowering of Groundwater Level Measurable Objectives §354.30(b) Preliminary MOs were established based on historical groundwater level data, along with input and desired future groundwater levels from domestic groundwater users, agricultural interests, environmental interests, and other Basin stakeholders. The input and desired conditions were used to formulate a range of alternative MO options, which were discussed by the GSAs and the GSC. Final MOs were voted on by the GSC members to recommend to the GSAs for approval as part of the full GSP. Preliminary MOs were established based on historical groundwater level data and input regarding desired future groundwater levels from domestic groundwater users, agricultural interests, environmental 14 Page 385 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO interests, and other public stakeholders. The input and desired conditions were used to formulate a range of conceptual MO scenarios. These scenarios were evaluated using the groundwater model developed during this GSP preparation to project the effects of future Basin operation and to select measurable objectives for the GSP. As previously discussed in Chapter 5 and Section 8.4.2, groundwater conditions in San Luis Valley and Edna Valley are significantly different. Therefore, as with the MTs, the approach to the MOs is different in the two valleys. San Luis Valley In San Luis Valley, definition of MOs within the historically observed range of groundwater elevations, but about 20 feet lower than fall 2020 water levels, was considered to preserve the City's desired flexibility to pursue reasonable and managed groundwater development to augment its potable water supply portfolio to serve its customer base. MOs for SLV-09, SLV-16, SLV-19, and SLV-12 were set within the range of historical data, but lower than current water levels (Table 8-1) (Figures 8-1 through 8-4). Edna Valley In Edna Valley, if recovery from drought levels is evident (EV-04, EV-09, EV-12), MOs were set at the high- water levels observed immediately prior to the drought (Spring 2011, in most cases) (Figures 8-5 through 8- 7). The rationale for this selection was that if the antecedent conditions before the recent drought are replicated, and no significant new groundwater pumping is occurring in the Basin, then the water level declines observed from 2012-2015 in the Basin will not be significantly exceeded in a similar drought. To the extent that groundwater elevations can recover to levels higher than the 2011 levels, the Basin will be more resilient to drought. For the wells in Edna Valley to monitor surface water/groundwater conditions (EV-01, EV-11), MOs were set at approximately the average of seasonal high water levels over the period of record (Figures 8-8, 8-9). RMS EV-01 shows that similar high water levels occur with regularity during wet periods, going back to the late 1950s. Therefore, this level was selected for the MOs for these wells because they are the naturally occurring water levels that have been observed for decades. The MO for RMS EV-16, located in the southeast area of Tiffany Ranch Road near the upgradient extent of the Basin, was set slightly below current water levels (Figure 8-7). This approach is to try to prevent further significant reductions in water levels at this location, since it does not appear to have experienced any recovery of water levels since 2015, and needs to maintain sufficient saturated thickness to sustain production for the service area. Since there is data uncertainty due to significant data gaps, MTs and MOs will be reviewed every 5 years during GSP updates throughout the twenty-year SGMA planning horizon to assess if the RMSs and the assigned MOs and MTs remain protective of sustainable conditions in the Basin. MTs and MOs may be modified in the future as hydrogeologic conditions are monitored through the implementation phase of SGMA. 8.4.3.2 Interim Milestones§354.30(a)(e) Interim milestones (IMs) are required to be included in the GSP. IMs at 5-year intervals for the MOs established at each RMS are included on Table 8-1. Preliminary IMs were developed for the 10 RMS established for the basin. In San Luis Valley, because there have been no historic declines in water levels, IMs were simply defined as being numerically equivalent to the MO throughout the SGMA period. In Edna Valley, Interim milestones were generally selected to define 15 Page 386 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO a smooth linear increase in water levels between the observed groundwater elevation at the RMS in 2020, and the MO as presented in Table 8-1. IMs may be adjusted at any time during the SGMA timeline. It is expected that they will be reconsidered at 5-year intervals when the Basin GSP is revised and updated. The monitoring of basin conditions during the initial 5-year period will provide good indicators on if the IMs are close to being met. Failure to meet IMs is not in and of itself an indication of undesired conditions, but is meant to provide information determining whether the 20-year goals are on track to being achieved. Alternative projects and management actions may be considered or pursued if the IMs are not being met. Table 8-1 summarizes the interim milestones for the RMS. 8.5 REDUCTION OF GROUNDWATER STORAGE SUSTAINABILITY INDICATOR §354.28(C)(2) 8.5.1 Undesirable Results As per §354.26 of the SGMA regulations, locally defined significant and unreasonable conditions were assessed based on review of historical groundwater data and stakeholder input during numerous public meetings, analysis of available data, and discussions with GSA staff. It is recognized based on well - established hydrogeologic principles that the Reduction of Groundwater Storage Sustainability Indicator is directly correlated to the lowering of water level Sustainability Indicator. Significant and unreasonable changes in groundwater storage in the Basin are those that: • Lead to long-term reduction in groundwater storage. • Interfere with other Sustainability Indicators. Assessment of groundwater in storage will initially be evaluated with the same RMS and associated water level MTs and MOs as the chronic lowering of groundwater levels sustainability criteria. As additional data is collected in the monitoring network described in Chapter 7, new RMS may be established, and appropriate SMCs determined by the GSAs. For the purposes of this GSP, the definition of undesired conditions for the Reduction of Groundwater Storage Sustainability Indicator is as follows: The Basin will be considered to have undesirable results if two or more than two RMS for groundwater storage within a defined area of the Basin (i.e., San Luis Valley or Edna Valley) display exceedances of the MTs for two consecutive Fall measurements. Geographically isolated exceedances will require investigation to determine if local or basin wide actions are required in response. 8.5.1.1 Criteria for Establishing Undesirable Results §354.2(b)(2) Significant and unreasonable Reduction of Groundwater Storage in the Basin are those that: • Reduce the ability of existing domestic wells of average depth to produce adequate water for domestic purposes (drought resilience). • Cause significant financial burden to those who rely on the groundwater basin. • Interfere with other SGMA Sustainability Indicators. 8.5.1.2 Potential Causes of Undesirable Results §354.2(b)(1) Conditions that could theoretically lead to an undesirable result include the following: 16 Page 387 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Continuation of current levels of Edna Valley pumpage without development of additional water supply projects, or development of additional municipal or agricultural pumping at significantly higher rates than are currently practiced. Maintenance of current or additional non -de minimis pumping may result in continued decline in groundwater elevations and exceedance of the proxy minimum threshold.. Expansion of de minimis pumping. Adding domestic de minimis pumpers in the areas of the Basin administered by the County may result in lower groundwater elevations, and an exceedance of the proxy minimum threshold. Extensive, unanticipated drought. Minimum thresholds are established based on reasonable anticipated future climatic conditions. Extensive, unanticipated droughts more severe than those on record may lead to excessively low groundwater recharge and unanticipated high pumping rates that could cause an exceedance of the proxy minimum threshold. 8.5.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses §354.2(b)(3) The effects of these undesirable results on the beneficial users and uses are the same effects as those discussed for the Chronic Lowering of Groundwater Levels Sustainability Indicator. The primary effects on the beneficial users (§354.26 (b)(3)) occurs from allowing multiple exceedances of the MTs in a small geographic are. Allowing a minimum of two exceedances in a network of 10 RMS wells is reasonable if the exceedances are distributed throughout the Basin. If the exceedances are clustered in a limited area, it indicates that significant unreasonable effects are being experienced by a localized group of landowners. Any exceedances will require investigation to determine the significance and causes of the observed conditions. 8.5.2 Minimum Thresholds §354.28(c)(2) Section §354.28(c)(2) of the SGMA regulations states that "The minimum threshold for reduction of groundwater storage shall be a total volume of groundwater that can be withdrawn from the basin without causing conditions that may lead to undesirable results. Minimum thresholds for reduction of groundwater storage shall be supported by the sustainable yield of the basin, calculated based on historical trends, water year type, and projected water use in the basin." This GSP will monitor changes in groundwater level at the RMSs as a proxy for the change in groundwater storage metric. As allowed in §354.36(b)(1) of the SGMA regulations, groundwater elevation data at the RMS will be reported annually as a proxy to track changes in the amount of groundwater in storage. Based on well -established hydrogeologic principles, stable groundwater elevations maintained above the MTs will limit depletion of groundwater from storage. Therefore, using groundwater elevations as a proxy, the MT is that the groundwater surface elevation averaged across all the wells in the groundwater level monitoring network will remain stable above the MT for chronic lowering of groundwater levels. In accordance with the SGMA regulation cited above, GSAs have the option of defining the MT metric as a calculated volume of groundwater in storage. As discussed in Chapter 6, separate estimates for total groundwater in storage were generated for the San Luis Valley and Edna Valley using methodology described in Chapter 6. Figure 6-21 presents these estimates. After the monitoring network described in Chapter 7 is established, and several years of water level data have been collected, a robust and repeatable method for directly quantifying groundwater in storage using the monitoring network may be developed and finalized. It is possible that in future versions of the GSP, the MT may be changed to be defined as the directly calculated amount of groundwater in storage. However, for the current 5-year planning horizon, water levels at the RMS will be used as a proxy for the groundwater in storage Sustainability Indicator. 17 Page 388 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.5.2.1 Information and Methods Used for Establishing Reduction of Storage Minimum Thresholds §354.28(b) (1) As with the chronic reduction of groundwater levels Sustainability Indicator, the primary source of data that was evaluated for the Sustainability Indicator of reduction of groundwater storage is historical groundwater elevation data maintained by the County. The information used for establishing the MOs and MTs for the chronic lowering of groundwater levels Sustainability Indicator included: • Historical groundwater elevation data from wells monitored by the County of San Luis Obispo. • Depths and locations of existing wells. • Maps of current and historical groundwater elevation data. • Input from stakeholders regarding significant and unreasonable conditions and desired current and future groundwater elevations communicated during public meetings and solicitation of public comment on various options of MTs and MOs presented in the public forum. • Results of modeling various project scenarios of future groundwater level conditions. Storage MTs will be measured by collecting water level measurements at the RMS sites in the monitoring network. The monitoring network and protocols used to measure groundwater elevations at the RMS are presented in Chapter 7. The Water Level Monitoring Network is presented in Figure 7-1. This data will be used to monitor groundwater elevations and assess changes in groundwater storage. 8.5.2.2 Relationship between Individual Minimum Thresholds and Other Sustainability Indicators §354.28(b) (2) The MTs for reduction in groundwater storage is a single value of average groundwater elevation over the entire Basin. Therefore, the concept of potential conflict between MTs at different locations in the Basin is not applicable. The reduction in groundwater storage MT could influence other Sustainability Indicators. The reduction in groundwater storage MT was selected to avoid undesirable results for other Sustainability Indicators, as outlined below: • Chronic lowering of groundwater levels. Because groundwater elevations will be used as a proxy for estimating groundwater pumping and changes in groundwater storage, the reduction in groundwater storage would not cause undesirable results for this Sustainability Indicator. • Seawater intrusion. This Sustainability Indicator is not applicable to this Basin. • Degraded water quality. The minimum threshold proxy of stable groundwater levels is not expected to lead to a degradation of groundwater quality. • Subsidence. Because future average groundwater levels will be stable, they will not induce any additional subsidence. • Depletion of interconnected surface waters. Groundwater levels measured at representative monitoring wells (SLV-12, EV-01, EV-11) will serve as a proxy for depletion of interconnected surface water. In addition, stream flow gages along SLO Creek will continue to measure surface water conditions in San Luis Valley, and proposed stream gages along Corral de Piedras Creek will serve to generate information on surface water inflow and outflow in Edna Valley, allowing for direct measurement of surface water gains and losses to the groundwater systems based on future hydrologic and pumping conditions in the Basin. However, MTs along the creeks are defined to avoid significant water declines in these areas, with the goal of minimizing any potential significant depletion of interconnected surface water flows. 8.5.2.3 Effects of Minimum Thresholds on Neighboring Basins §354.28(b)(3) Two neighboring groundwater basins share a boundary with the SLO Basin; the Los Osos Basin to the northwest, and the Arroyo Grande sub -basin of the Santa Maria Valley Groundwater Basin to the southeast. Neither of these shared boundaries are extensive, and the HCM posits that a groundwater divide separates the groundwater between them and the SLO Basin. In the San Luis Valley there have been no Page 389 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO trends indicating groundwater declines that would affect the Los Osos Basin. In Edna Valley the areas with observed declines are one to two miles from the Arroyo Grande Basin boundary in a downgradient direction. It is not anticipated that actions associated with the GSP will have any significant impact on either the Los Osos Basin or the Arroyo Grande Basin. The SLO Basin GSAs have developed a cooperative working relationship with the Los Osos Groundwater Basin — Basin Management Committee and the GSAs working in the Arroyo Grande Subbasin. Groundwater conditions near the borders with these basins will be monitored and shared. 8.5.2.4 Effects of Minimum Thresholds on Beneficial Uses and Users §354.28(b)(4) The MT for reduction in groundwater storage will maintain stable average groundwater elevations, but may require a reduction in the amount of groundwater pumping in the Basin, or development of sources of supplemental water as discussed in Chapter 9. Reducing pumping may impact the beneficial uses and users of groundwater in the Basin. The practical effect of this GSP for protecting against the reduction in groundwater storage undesirable result is that it encourages minimal long-term net change in groundwater elevations and storage. Seasonal and drought cycle variations are expected, but during average conditions and over the long-term, beneficial users will have access to adequate volumes of water from the aquifer to service the needs of all water use sectors. The beneficial users of groundwater are protected from undesirable results. Agricultural Land Uses and Users The MT for reduction in groundwater storage may limit or reduce non -de minimis production in the Basin by reducing the amount of available water. The practical effect of these MTs on agricultural users is that current levels of agricultural pumping may not be sustainable without development of additional sources of water to the Basin. Owners of undeveloped agricultural lands that are currently not irrigated may be particularly impacted because the additional groundwater pumping needed to irrigate these lands could increase the Basin pumping beyond the sustainable yield, violating the MT. Existing agricultural operations may also be limited in their use of more water -intensive crops, expansion of existing irrigated lands, and by periods of extended drought that decrease the quantity of water naturally returning to the basin. Urban Land Uses and Users Potential future increases of groundwater pumping in the City of San Luis Obispo could decrease the cost of water for municipal users in the City, because groundwater may be the cheapest water supply alternative. However, in order to avoid undesirable results, the City is unlikely to pursue groundwater pumping in the quantity that it did during the 1980s-90s drought without the use of groundwater recharge. Domestic Land Uses and Users Existing domestic groundwater users may generally benefit from this MT. Many domestic groundwater users are de-minimis users whose pumping may not be restricted by the projects and management actions adopted in this GSP. By restricting the amount of groundwater that is pumped from the Basin, the de- minimis users would be protected from overdraft that could impact their ability to pump groundwater or require them to drill deeper wells. Ecological Land Uses and Users. Groundwater dependent ecosystems would generally benefit from this MT. Maintaining groundwater levels close to current levels keeps groundwater supplies near present levels, which will continue to support groundwater dependent ecosystems. 8.5.2.5 Relation to State, Federal, or Local Standards §354.28(b)(5) No federal, state, or local standards exist for reductions in groundwater storage. 19 Page 390 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.5.2.6 Methods for Quantitative Measurement of Minimum Threshold §354.28(b)(6) The quantitative metric for assessing compliance with the reduction in groundwater storage MT is monitoring groundwater elevations. The approach for quantitatively evaluating compliance with the MT for reduction in groundwater storage will be based on evaluating groundwater elevations semi-annually. All groundwater elevations collected from the groundwater level monitoring network will be analyzed and averaged. In the future, after the monitoring network is established and multiple years of data are available for analysis, a robust and repeatable method for calculating groundwater in storage utilizing the monitoring well network may be developed and finalized. At that time, the metric for defining the SMC of reduction of groundwater in storage may possibly be changed to direct calculation of groundwater in storage for the two areas of the basin, but this will be reviewed after additional data has been collected during the implementation phase of the GSP. 8.5.3 Measurable Objectives §354.30(a)-(g) The change in storage Sustainability Indicator uses groundwater levels as a proxy for direct calculation of groundwater in storage. The same MTs and MOs are used as are defined in the chronic lowering of groundwater level indicator to protect against significant and unreasonable reduction in groundwater storage. 8.5.3.1 Information and Methods Used for Establishing Reduction of Groundwater Storage Measurable Objectives §354.30(b) Input from stakeholders suggested that they would prefer more groundwater in storage to maintain resiliency against future droughts. Therefore, the conservative approach of simply maintaining stable groundwater levels was adopted for the MO. MOs for the RMS are identical to the MOs for the chronic lowering of groundwater elevations MOs (Table 8-1). 8.5.3.2 Interim Milestones §354.30(a)(e) Interim milestones for groundwater storage are the same as those established for chronic lowering of groundwater elevations. Achieving the groundwater elevation interim milestones will also eliminate long term reductions in groundwater in storage. Interim milestones are included on Table 8-1. 8.6 SEAWATER INTRUSION SUSTAINABILITY INDICATOR §354.28(C)(3) This Sustainability Indicator does not apply to the Basin since the Basin is not a coastal basin. 8.7 DEGRADATION OF GROUNDWATER QUALITY SUSTAINABILITY INDICATOR §354.28(C)(4) The purpose of the Degraded Water Quality Indicator in SGMA is to prevent any degradation in groundwater quality as a result of groundwater management under the GSP. SGMA is not intended to serve as impetus to improve water quality within the Basin. The Basin's current water quality is not considered degraded. For these reasons, the SMC in this section are set to maintain current conditions in the Basin, protecting from potential degradation as a result of groundwater management under this GSP. 8.7.1 Undesirable Results §354.26(a)-(d) Section §354.28(c)(2) of the SGMA regulations states that "The minimum threshold shall be based on the number of supply wells, a volume of water, or a location of an isocontour that exceeds concentrations of constituents determined by the Agency to be of concern for the basin." 20 Page 391 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO By SGMA regulations, the Degraded Groundwater Quality undesirable result is a quantitative combination of groundwater quality minimum threshold exceedances. The undesirable results for the Degraded Water Quality Sustainability Indicator as defined for the purposes of this GSP are as follows: The Basin will be considered to have Undesirable Results if, for any year, an increase in groundwater quality minimum threshold exceedances are observed at 20 percent or more of the representative monitoring sites in the Basin, in relation to 2015 Basin conditions, as a result of groundwater management implemented as part of the GSP. The undesirable conditions for degraded water quality in the Basin are based on the goal of fewer than 20% of the RMSs for water quality exceedances that can occur as a result of GSP groundwater management activities over the next 5-year management period. Based on the current number of wells in the existing water quality monitoring network described in Chapter 7, the percentage defined equates to a maximum of two wells that can exceed the minimum thresholds. Specifics regarding the definition of the MTs used in defining the Undesirable Results are detailed in the following sections. A summary of the MTs defined for the Degradation of Water Quality Sustainability Indicator are presented in Table 8.2. Table 8-2. San Luis Obispo Basin Groundwater Basin Water Quality Minimum Thresholds ID TDS MT NO3 MT Arsenic MT TCE, PCE (PPM) (PPM) (Ppb) (ppb) WQ-1 900 10 10 5 WQ-2 900 10 10 5 WQ-3 900 10 10 5 WQ-4 900 10 10 5 WQ-5 900 10 10 5 WQ-6 900 10 10 5 WQ-7 900 10 10 5 WQ-8 900 10 10 5 WQ-9 900 10 10 5 8.7.1.1 Criteria for Establishing Undesirable Results §354.26(b)(2) Criteria used to establish the Undesirable Results for Degraded Water Quality Sustainability Indicator are observed water quality data and trends that: • Reduce capacity of public water supply systems or unreasonably increase costs for public or private water supply. • Reduce crop production. • Result in constituent concentrations above regulatory primary drinking water standards at supply wells. • Results in constituent concentrations above the RWQCB Basin Objectives for secondary standards (TDS) 21 Page 392 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.7.1.2 Potential Causes of Undesirable Results §354.26(b)(1) Conditions that may lead to an undesirable result include the following: • Changes to Basin Pumping: If the location and rates of groundwater pumping change as a result of projects implemented under the GSP, these changes could cause movement of one of the constituents of concern towards a supply well at concentrations that exceed relevant water quality standards. • Groundwater Recharge: Active recharge with imported water or captured runoff could cause movement of one of the constituents of concern towards a supply well in concentrations that exceed relevant water quality standards. • Recharge of Poor -Quality Water: Recharging the Basin with water that exceeds a primary or secondary MCL or concentration that reduces crop production could lead to an undesirable result. However, permitting requirements generally preclude this circumstance. 8.7.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses §354.26(b)(3) As defined in this GSP, undesirable results are established to prevent degradation of water quality within the Basin prior to the implementation of any actions inherent in the management of groundwater in the Basin. This limits the potential impacts of undesirable water quality on beneficial users in the Basin. However, potential effects of undesirable results include: • Increased water treatment costs for public or private supply wells • Reduced agricultural production 8.7.2 Minimum Thresholds § 354.28(c)(4) 8.7.2.1 Information and Methods Used for Establishing Degradation of Water Quality Minimum Thresholds § 354.28 (b)(1) Locally defined significant and unreasonable conditions were assessed based on federal and state mandated drinking water and groundwater quality regulations, the Sustainable Management Criteria survey, public meetings, and discussions with GSA staff. Significant and unreasonable changes in groundwater quality in the Basin are increases in a chemical constituent that either: • Result in groundwater concentrations in a public supply well above an established primary or secondary MCL, or • Lead to reduced crop production. The information used for establishing the degraded groundwater quality minimum thresholds included: • Historical groundwater quality data from production wells in the Basin • Federal and state primary drinking water quality standards • RWQCB Basin objectives for groundwater quality (2019) for TDS • Feedback about significant and unreasonable conditions from GSC members, GSA staff members, and public stakeholders The historical groundwater quality data used to evaluate groundwater quality minimum thresholds are presented in Chapter 5 (Figures 5-16 through 5-18). As stated in Section 8.7.1, the SGMA regulations allow three options to develop an approach for setting degraded water quality minimum thresholds (number of wells, volume of water, or location of concentration isocontour). In the Basin, degraded water quality minimum thresholds are based on EPA - published water quality standards (EPA, 2018) for constituents of concern with a primary or secondary MCL is to avoid degrading the existing water quality with respect to these constituents in the Basin. (Primary standards refer to chemical constituents in groundwater with a potential impact on human health; secondary standards refer to constituents that may affect taste or odor of drinking water.) 22 Page 393 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO As noted in Section 354.28 (c)(4) of the SGMA regulations, minimum thresholds are based on a degradation of groundwater quality, not an improvement of groundwater quality. Therefore, this GSP was developed to avoid taking actions that may inadvertently move groundwater constituents that have already been identified in the Basin in such a way that they have a significant and unreasonable impact that would not otherwise occur. Based on the review of groundwater quality in Chapter 5, water quality in the basin is generally good. The primary constituents of concern that exist for both agricultural wells and public supply wells are: • Total Dissolved Solids (TDS) • Nitrate • Arsenic • Volatile Organic Compounds (PCE and TCE) As noted in Section 5.6.3, based on available information there are two known groundwater contamination plumes in the Basin: The TCE plume along Buckley Road south of the airport, and a PCE plume within the City. Both of these cases are under active investigation with oversight by the RWQCB. The MTs for the constituents of concern are presented in Table 8-2. 8.7.2.2 Relation of Minimum Thresholds to Other Sustainability Indicators § 354.28(b)(2) The groundwater quality minimum thresholds were set for each of four constituents previously discussed. These minimum thresholds were derived from existing data measured at individual wells and applicable regulatory criteria. There are no conflicts between the existing groundwater quality data. Because the underlying groundwater quality distribution is reasonable and realistic, there is no conflict that prevents the Basin from simultaneously achieving all minimum thresholds. No actions regarding the MTs for Water Quality will directly influence other Sustainability Indicators. However, preventing migration of poor groundwater quality (for example, actions required to prevent additional migration of contaminant plumes) could theoretically limit activities needed to achieve minimum thresholds for other Sustainability Indicators, as discussed below: • Change in groundwater levels. Groundwater quality minimum thresholds could influence groundwater level minimum thresholds by limiting the types of water that can be used for recharge to raise groundwater levels or locations where it could be recharged. Water used for recharge cannot exceed any of the groundwater quality minimum thresholds. • Change in groundwater storage. Nothing in the groundwater quality minimum thresholds promotes pumping in excess of the sustainable yield. The groundwater quality minimum thresholds will not result in an exceedance of the groundwater storage minimum threshold. • Seawater intrusion. This Sustainability Indicator is not applicable to this basin. • Subsidence. Nothing in the groundwater quality minimum thresholds promotes a condition that will lead to additional subsidence and therefore, the groundwater quality minimum thresholds will not result in a significant or unreasonable level of subsidence. • Depletion of interconnected surface waters. Nothing in the groundwater quality minimum thresholds promotes additional pumping or lower groundwater elevations in areas where interconnected surface waters may exist. Therefore, the groundwater quality minimum thresholds will not result in a significant or unreasonable depletion of interconnected surface waters. 23 Page 394 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.7.2.3 Effect of Minimum Thresholds on Neighboring Basins § 354.28(b)(3) Because there is a groundwater divide between the SLO Basin and the adjacent Los Osos Basin and Arroyo Grande sub -basin, there is no anticipated effect of the degraded groundwater quality minimum thresholds on each of the two neighboring Basins. 8.7.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses § 354.28(b)(4) The practical effect of the MTs for the Degraded Groundwater Quality Sustainability Indicator is that it deters any significant long-term changes to groundwater quality in the Basin. Therefore, Basin management that prevents the undesirable results from occurring will not constrain the use of groundwater, nor have a negative effect on the beneficial users and uses of groundwater. Agricultural land uses and users. The degraded groundwater quality minimum thresholds generally benefit the agricultural water users in the Basin by maintaining groundwater quality suitable for use in agriculture. For example, limiting the number of additional agricultural supply wells that may exceed constituent of concern concentrations (for example, TDS) that could reduce crop production ensures that a supply of usable groundwater will exist for beneficial agricultural use. Urban land uses and users. The degraded groundwater quality minimum thresholds generally benefit the urban water users in the Basin. Limiting the number of additional wells where constituents of concern could exceed primary or secondary MCLs ensures an adequate supply of quality groundwater for municipal use. Management of the Basin to prevent occurrences of these MTs may also result in lowered costs for water treatment. Existing State, Federal, Public Health or Municipal regulations may require that a well not be used if MCLs are exceeded and may supersede any actions related to SGMA-related MT exceedances. Wells in violation of federal, state, and local water quality regulations will have to comply with the specific regulations. Domestic land uses and users. The degraded groundwater quality minimum thresholds generally benefit the domestic water users in the Basin by maintaining current and acceptable water quality. Ecological land uses and users. Although the groundwater quality minimum thresholds do not directly benefit ecological uses, it can be inferred that the degraded groundwater quality minimum thresholds generally benefit the ecological water uses in the Basin. Preventing constituents of concern from migrating will prevent unwanted contaminants from impacting ecological groundwater supply. 8.7.2.5 Relevant Federal, State, or Local Standards § 354.28(b)(5) The Degraded Groundwater Quality minimum thresholds specifically incorporate federal and state drinking water standards. 8.7.2.6 Method for Quantitative Measurement of Minimum Thresholds § 354.28(b)(6) The Degraded Groundwater Quality minimum thresholds will be directly measured using analytical laboratory results of sampling conducted at the RMSs of the Water Quality Monitoring Network presented in Chapter 7. Groundwater quality will initially be measured using existing monitoring programs. • Exceedances of primary or secondary MCLs will be monitored by reviewing water quality reports submitted to the California Division of Drinking Water by municipalities and small water systems for the wells that are included in the Water Quality Monitoring Network. 8.7.3 Measurable Objectives § 354.30(a)-(g) Groundwater quality should not be degraded due to actions taken under this GSP and, therefore, the measurable objectives are defined as zero exceedances as a result of groundwater management, in samples from the Water Quality Monitoring Network wells over the 20-year SGMA planning horizon. 24 Page 395 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.7.3.1 Information and Methods Used for Establishing Degradation of Water Quality Measurable Objectives § 354.30(b) Because protecting groundwater quality is important to the beneficial users and uses of the resource, the measurable objective for the Degradation of Water Quality Sustainability Indicator is defined as zero exceedances of the MTs over the 20-year SGMA planning horizon. Any exceedance will be reviewed by the GSAs to determine its significance and potential responses. 8.7.3.2 Interim Milestones § 354.28(a)(e) Interim milestones show how the GSAs anticipate moving from current conditions to meeting the measurable objectives. For water quality, measurable objectives are set at the current number of water quality exceedances, which in this case is zero. Interim milestones are set for each five-year interval following GSP adoption. The interim milestones for degraded groundwater quality are defined as zero exceedances of the MT for each constituent of concern for 5, 10 and 15 years after GSP adoption. 8.8 LAND SUBSIDENCE SUSTAINABILITY INDICATOR § 354.28(C)(5) 8.8.1 Undesirable Results § 354.26(a)-(d) Locally defined significant and unreasonable conditions for the Land Subsidence Sustainability Indicator were assessed based on public meetings and discussions with GSA staff. Significant and unreasonable rates of land subsidence in the Basin are those that lead to a permanent subsidence of land surface elevations that impact infrastructure. For clarity, this Sustainable Management Criterion references two related concepts: • Land Subsidence is a gradual settling of the land surface caused by, among other processes, compaction of subsurface materials due to lowering of groundwater elevations from groundwater pumping. Land subsidence from dewatering subsurface clay layers can be an inelastic process, and the potential decline in land surface could be permanent. • Land Surface Fluctuation is the periodic or annual measurement of the ground surface elevation. Land surface may rise or fall in any one year. Declining land surface fluctuation may or may not indicate long-term permanent subsidence. Subsidence was documented in the Los Osos Valley in the early 1990s. Currently, InSAR data provided by DWR shows that significant land subsidence did not occur in the Basin during the period between June 2015 and June 2018. By regulation, the ground surface Land Subsidence undesirable result is a quantitative combination of subsidence minimum threshold exceedances. For the Basin, no long-term subsidence that impacts infrastructure (including commercial buildings, homes, utility infrastructure, etc.) is acceptable. The Undesirable Results for the land subsidence Sustainability Indicator as defined for the purposes of this GSP are as follows: The Basin will be considered to have Undesirable Results if measured subsidence using InSAR data, between June of one year and June of the subsequent year is greater than 0.1 foot in any 1-year, or a cumulative 0.5 foot in any 5-year period, as a result of groundwater management under the GSP, or any long-term permanent subsidence is attributable to groundwater management. 25 Page 396 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO Should potential subsidence be observed, the GSAs will first assess whether the subsidence may be due to elastic processes. If the subsidence is not elastic, the GSAs will undertake a program to correlate the observed subsidence with measured groundwater levels. 8.8.1.1 Criteria for Establishing Undesirable Results § 354.26(b)(2) Criteria used to establish the Undesirable Results for Land Subsidence Sustainability Indicator are satellite - measured subsidence data (InSAR data) collected by DWR. 8.8.1.2 Potential Causes of Undesirable Results § 354.26(b)(1) Conditions that may lead to an undesirable result include: • A shift in pumping locations, which could lead to a substantial decline in groundwater levels. • Shifting a significant amount of pumping and causing groundwater levels to fall in an area that is susceptible to subsidence, such as certain areas underlaying the City, could trigger subsidence in excess of the minimum threshold. 8.8.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses § 354.26(b)(3) The effects of these undesirable results on the beneficial users and uses (§354.26 (b)(3)) include the damage of critical infrastructure, and the damage of private or commercial structures that would adversely affect their uses. Staying above the minimum threshold will avoid the subsidence undesirable conditions. 8.8.2 Minimum Thresholds § 354.28(c)(5) Section 354.28(c)(5) of the SGMA regulations states that "The minimum threshold for land subsidence shall be the rate and extent of subsidence that substantially interferes with surface land uses and may lead to undesirable results." Based on an analysis of potential errors in the InSAR data, as discussed in the following section, the subsidence minimum threshold is: The InSAR measured subsidence between June of one year and June of the subsequent year shall be no more than 0.1 foot in any single year and a cumulative 0.5 foot in any five- year period, resulting in no long-term permanent subsidence. Although InSAR data is the official minimum threshold value for the land subsidence Sustainability Indicator, the GSAs have included one well to monitor for water levels as a proxy for potential subsidence. Regular data collection from this well could alert the GSAs to conditions that may lead to subsidence before InSAR data are available. RMS SLV-09 along Los Osos Valley Road is in the area of the basin that experienced significant subsidence in the early 1990s. Therefore, this well has been selected to monitor for conditions that could lead to subsidence. The minimum threshold for this well is set at 102 feet, 15 feet higher than the observed low water level in the early 1990s. 8.8.2.1 Information and Methods Used for Establishing Land Subsidence Minimum Thresholds § 354.28(b)(1) Minimum thresholds were established to protect groundwater supply, land uses and property interests from substantial subsidence that may lead to undesirable results. Changes in surface elevation are measured using InSAR data available from DWR. The general minimum threshold is the absence of long- term land subsidence due to pumping in the Basin. The InSAR data provided by DWR, however, are subject to measurement error. DWR has stated that, on a statewide level, for the total vertical displacement measurements between June 2015 and June 2018, the errors are as follows (GSP, Paso Robles Basin, 2020): 1. The error between InSAR data and continuous GPS data is 16 mm (0.052 feet) with a 95% confidence level. 2. The measurement accuracy when converting from the raw InSAR data to the maps provided by DWR is 0.048 feet with 95% confidence level. 26 Page 397 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO For the purposes of this GSP, the errors for InSAR data is considered the sum of errors 1 and 2, combined total error of 0.1 foot. Thus, measured land surface change of greater than 0.1 feet will be assessed as potential subsidence. As discussed previously, land surface elevations can fluctuate naturally. Therefore, subsidence will be monitored at the same time each year to reduce the effect of general fluctuations of elevation on observed data. Additionally, if subsidence is observed, a correlation to lowered groundwater elevations at RMS SLV-09 must exist for the minimum threshold to be exceeded. Locally defined significant and unreasonable conditions are assessed based on historically observed water levels in areas of known past land subsidence, satellite -based measurements of land subsidence provided by DWR, public meetings, and discussions with GSA staff. 8.8.2.2 Relation of Minimum Thresholds to Other Sustainability Indicators § 354.28(b)(2) Land Subsidence minimum thresholds have little or no impact on other minimum thresholds, as described below: • Chronic lowering of groundwater elevations. The Land Subsidence minimum thresholds will not result in significant or unreasonable groundwater elevations. • Change in groundwater storage. The Land Subsidence minimum thresholds will not change the amount of pumping, and will not result in a significant or unreasonable change in groundwater storage. • Seawater intrusion. This Sustainability Indicator is not applicable in the Basin. • Degraded water quality. The Land Subsidence minimum thresholds will not change the groundwater flow directions or rates, and therefore and will not result in a significant or unreasonable change in groundwater quality. • Depletion of interconnected surface waters. The Land Subsidence minimum thresholds will not change the amount or location of pumping and will not result in a significant or unreasonable depletion of interconnected surface waters. 8.8.2.3 Effect of Minimum Thresholds on Neighboring Basins § 354.28(b)(3) The ground surface subsidence minimum thresholds are set to prevent any long-term subsidence that could harm infrastructure. Therefore, the subsidence minimum thresholds will not prevent the Los Osos Basin or the Arroyo Grande Basin from achieving sustainability. 8.8.2.4 Effects of Minimum Thresholds on Beneficial Users and Land Uses § 354.28(b)(4) The Land Subsidence minimum thresholds are set to prevent subsidence that could harm infrastructure. Available data indicate that there is currently no subsidence occurring in the Basin that affects infrastructure, and reductions in pumping are already required by the reduction in groundwater storage Sustainability Indicator. Therefore, the Land Subsidence minimum thresholds do not require any additional reductions in pumping. However, in general the amount of pumping in the Los Osos Valley Road area must be kept at levels significantly lower than implemented in the 1990s. Staying above the minimum threshold will avoid the Land Subsidence undesirable result and protect the beneficial uses and users from impacts to infrastructure and interference with surface land uses. 8.8.2.5 Relevant Federal, State, or Local Standard § 354.28(b)(5) There are no federal, state, or local regulations related to subsidence. 8.8.2.6 Method for Quantitative Measurement of Minimum Thresholds § 354.28(b)(6) Minimum thresholds will be assessed using DWR-supplied InSAR data. 27 Page 398 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.8.3 Measurable Objectives § 354.30(a)-(g) The measurable objectives for subsidence represent target subsidence rates in the Basin. Long-term ground surface elevation data do not suggest the occurrence of permanent subsidence in the Basin. Therefore, the measurable objective for subsidence is maintenance of current ground surface elevations. 8.8.3.1 Information and Methods Used for Establishing Land Subsidence Measurable Objectives 0§ 354.3(b) The measurable objectives are set based on maintaining current conditions and changes are measured by DWR-supplied InSAR data. 8.8.3.2 Interim Milestones § 354.28(a)(e) Interim milestones show how the GSAs anticipate moving from current conditions to meeting the measurable objectives. Interim milestones are set for each five-year interval following GSP adoption. Land Subsidence measurable objectives are set at current conditions of no long-term subsidence. There is no change between current conditions and sustainable conditions. Therefore, the interim milestones are identical to the minimum thresholds and measurable objectives. 8.9 DEPLETION OF INTERCONNECTED SURFACE WATER SUSTAINABILITY INDICATOR § 354.28(C)(6) Natural hydraulic connections can exist between shallow groundwater systems and some surface water bodies. These surface water bodies can be gaining (receiving discharge from the alluvial aquifer) or losing (discharging water to the alluvial aquifer). These relationships may change in magnitude and direction across wet and dry cycles, and in response to changes in surface water operations or groundwater management practices. Depletions of interconnected surface water occurs when there are decreased gains or increased losses in volumes of streamflow caused by lowered groundwater elevations associated with groundwater use. At certain levels, depletions may have adverse impacts on beneficial uses of the surface water and may lead to undesirable results. Direct measurement of flux between an aquifer and an interconnected stream is not feasible using currently available data. A number of proposals to improve the collection of surface water and interconnected groundwater data are discussed in Chapter 7 (Monitoring Networks), and proposed details for these tasks are discussed in Chapter 10 (Implementation Plan). Until immediately adjacent such time as this data is available, this GSP uses water level measurements in representative wells located immediately adjacent to Basin creeks as the SMCs for the Depletion of Interconnected Surface Water Sustainability Indicator. 8.9.1 Undesirable Results § 354.26(a)-(d) The undesirable result for Depletions of Interconnected Surface Water is a result that causes significant and unreasonable adverse effects on beneficial uses of interconnected surface water within the Basin over the planning and implementation horizon of this GSP. As discussed in Section 8.9, measurement of the fluxes between the aquifer and Basin creeks is not feasible with currently available data. Therefore, water level measurements at the RMSs designated for the Depletion of Interconnected Surface Water Sustainability Indicator will be used as the basis MTs and Undesirable Results until better data becomes available under future monitoring activities. The statement defining undesirable results for the Depletion of Interconnected Surface Water for this GSP is as follows: W. Page 399 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO The Basin will be considered to have undesirable results if any of the representative wells monitoring groundwater/surface water interaction display exceedances of the minimum threshold values for two consecutive Fall measurements. 8.9.1.1 Criteria for Establishing Undesirable Results § 354.26(b)(2) Criteria used to define undesired conditions for this Sustainability Indicator are those that: • Impact the ability of the stream system to meet instream flow requirements and maintain groundwater dependent ecosystems (GDEs) • Impact the ability to provide surface water supplies to direct diverters • Interfere with other SGMA Sustainability Indicators. The information used for establishing the criteria for undesirable results for the Depletion of Interconnected Surface Water Sustainability Indicator is water levels data collected from three RMS wells (i.e., SLV-12 and EV-01, and EV-11) that are located immediately adjacent to San Luis Obispo and Corral de Piedras Creek systems. For the present, water levels in these wells will be used as a proxy indicator of undesirable results. 8.9.1.2 Potential Causes of Undesirable Results § 354.26(b)(1) Potential causes of undesirable results include increases in pumping in the proximity of a Basin creeks, or instream projects that could alter the natural flow regimes of the creeks. 8.9.1.3 Effects of Undesirable Results on Beneficial Users and Land Uses § 354.26(b)(3) If depletions of interconnected surface water were to reach undesirable results, adverse effects could include the reduced ability of the stream flows to meet instream flow requirements for local fisheries and critical habitat, or reduced ability to deliver surface water supplies to direct users of surface water in the Basin. 8.9.2 Minimum Thresholds Section 354.28(c)(6) of the SGMA regulations states that "The minimum threshold for depletions of interconnected surface water shall be the rate or volume of surface water depletions caused by groundwater use that has adverse impacts on beneficial uses of the surface water and may lead to undesirable results." Current data are insufficient to determine the rate or volume of surface water deletions in the creeks. Therefore, groundwater elevations in the RMSs intended to monitor surface water/groundwater interaction (SLV-12, EV-01, EV-11) are used as a proxy for the Depletion of Interconnected Surface Water Sustainability Indicator. If in the future, data from a more comprehensive monitoring program (as discussed in chapter 7 and Chapter 10) succeed in quantifying surface water depletions, those data may be used to re -define minimum thresholds for areas of interconnection. Minimum thresholds for these representative wells are presented in Table 8-1 and Figures 8-4, 8-98, and 8-10. RMS EV-01 is located along West Corral de Piedras Creek just where it enters the Basin, and EV-11 (Greengate) is located near the junction of East and West Corral de Piedras, near the outlet of the Basin. These wells are screened at least partially in the alluvial sediments associated with the creek, and therefore, reflect groundwater conditions in the alluvial sediments. Hydrographs for these wells display seasonal fluctuation of about 50 feet, which occur during wet and dry climatic periods. To avoid management conditions that allow for lower groundwater elevations than those historically observed, MTs for these wells were set at the historic low water levels indicated on the hydrographs, which occur with regularity during every extended dry period evident in the record (Figures 8-9, 8-10). 29 Page 400 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO San Luis Obispo Creek is a significant feature in the Basin. It is an unregulated (Le., undammed) creek. Some reaches of San Luis Obispo Creek in the Basin have been observed to maintain flow year-round, and some reaches go dry in the summer. A more extensive description and quantification of the stream/aquifer interaction is included in Chapter 5 — Groundwater Conditions and Chapter 6 — Water Budget. The water budget shows that flow conditions in the creek are highly variable depending on rainfall events and the hydrologic year type. In wetter years, when flows in the San Luis Obispo Creek are high there is greater amounts of discharge from the creek to the groundwater system. In drier years, when flows in the San Luis Obispo Creek are low, there is less stream recharge to the groundwater system. In both cases the amount of flux between the surface water and the groundwater system is small compared to the volume of water flowing down the creek. Inspection of hydrographs for RMS SLV-12, intended to monitor conditions along near San Luis Obispo Creek (Figure 8-4) do not indicate any significant declines of water levels since the drought of the early 1990s. Therefore, this data suggests that the mechanisms of surface water/groundwater interaction at this location have not been negatively impacted since the early 1990s. East and West Corral de Piedras Creeks meet to form Pismo Creek just south of the basin boundary in Edna Valley. Corral de Piedras Creeks are significant features in the Edna Valley portion of the SLO Basin. West Corral de Piedras is affected by a private dam that impounds water at the Righetti Reservoir upstream from the basin. To the extent that captured flows impounded in Righetti Reservoir do not naturally flow downstream, the amount of stream flow is reduced and ancillary basin recharge via streamflow percolation is less than it would be under natural (Le., undammed) conditions in the Edna Valley. East and West Corral de Piedras Creeks in the Basin are not observed to maintain flow year-round in most of the Basin. Inspection of hydrographs for RMS EV-01, intended to monitor conditions near West Corral de Piedras Creeks where it enters the Basin (Figure 8-9, 8-10) indicate highly seasonal groundwater conditions which fluctuate between well -established high points near ground surface and low points significantly deeper than the assumed creek bed elevation, and do not reflect any significant long-term declines of water levels in the observed period of record dating back to the late 1950s. This hydrograph pattern indicates that surface water in Corral de Piedras Creeks recharges the underlying aquifer when the creek is flowing, and is disconnected from the underlying aquifer system when the creek is dry. As described in Chapter 4, Hydrogeologic Conceptual Model and Chapter 5, Groundwater Conditions, there are insufficient data to quantitatively assess the extent of the connection between surface water and groundwater in the Basin. As described in Chapter 7, Monitoring Networks, a more expansive monitoring network will be developed during GSP implementation to improve understanding of interconnection between surface water and groundwater in the Basin. Chapter 10 (Implementation Plan) addresses details of the plan to accumulate better data for this Sustainability Indicator. If in the future, better data are generated to quantify the connection between surface water and groundwater, undesirable results may be revised to reflect this data. However, for this GSP, groundwater elevations in SLV-12, EV-01, and EV-11 will be used as a proxy for the Depletion of Interconnected Surface Water Sustainability Indicator. 8.9.2.1 Information and Methods Used for Establishing Depletion of Interconnected Surface Water Minimum Thresholds As with the other Sustainability Indicators, the primary methods for development of SMCs for this Sustainability Indicator is monitoring of groundwater elevations in the three RMSs established for the purpose of monitoring hydrogeologic conditions in the adjacent creeks. As with the chronic reduction of groundwater levels Sustainability Indicator, the primary source of data that was evaluated for the Depletion of Interconnected Surface Water Sustainability Indicator is historical groundwater elevation data maintained by the GSAs. The information used for establishing the MOs and MTs for the chronic lowering of groundwater levels Sustainability Indicator included: 30 Page 401 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO • Historical groundwater elevation data from wells monitored by the County of San Luis Obispo. • Construction details of RMS wells • Long-term trends displayed in hydrographs of the RMS wells identified for this Sustainability Indicator. The use of groundwater elevation as a proxy metric for the Depletion of Interconnected Surface Water Sustainability Indicator is adopted given the challenges and cost of direct monitoring of depletions of interconnected surface water. The depletion of interconnected surface water is driven by the gradient between water surface elevation in the surface water body and groundwater elevations in the connected, shallow groundwater system. By defining minimum thresholds in terms of groundwater elevations in shallow groundwater wells near surface water, the GSAs will monitor and manage this gradient, and in turn, manage potential changes in depletions of interconnected surface. 8.9.2.2 Relationship between Individual Minimum Thresholds and Other Sustainability Indicators The MTs for the Depletion of Interconnected Surface Water Sustainability Indicator are defined as the lowest water levels observed in the period of record for each of the three RMSs. Therefore, the concept of potential conflict between MTs at different locations in the Basin is not applicable. The Depletion of Interconnected Surface Water Sustainability Indicator could influence other Sustainability Indicators. The Depletion of Interconnected Surface Water Sustainability Indicator MTs was selected to avoid undesirable results for other Sustainability Indicators, as outlined below: • Chronic lowering of groundwater levels. Because groundwater elevations will be used as a proxy for estimating Depletion of Interconnected Surface Water Sustainability Indicator, and the definitions of the MTs are set at historically observed conditions, the MTs will not cause undesirable results for this Sustainability Indicator. • Depletion of Groundwater Storage. Because groundwater elevations will be used as a proxy for estimating Depletion of Interconnected Surface Water Sustainability Indicator, and the definitions of the MTs are set at historically observed conditions, the MTs will not cause undesirable results for this Sustainability Indicator. • Seawater intrusion. This Sustainability Indicator is not applicable to this Basin. • Degraded water quality. The minimum threshold proxy of stable groundwater levels is not expected to lead to a degradation of groundwater quality. • Subsidence. Because future groundwater levels will be above historically observed conditions, they will not induce any additional subsidence. 8.9.2.3 Effects of Minimum Thresholds on Neighboring Basins Two neighboring groundwater basins share a boundary with the SLO Basin; the Los Osos Basin to the northwest, and the Arroyo Grande Subbasin of the Santa Maria Valley Groundwater Basin to the southeast. Neither of these shared boundaries are extensive, and the HCM posits that a groundwater divide separates the groundwater between them and the SLO Basin. In addition, the Basin streams are relatively far from the Basin boundaries shared with the neighboring basins. In the San Luis Valley there have been no trends indicating groundwater declines that would affect the Los Osos Basin. In Edna Valley the areas with observed declines are one to two miles from the Arroyo Grande Basin boundary in a downgradient direction. It is not anticipated that actions associated with the GSP will have any significant impact on either the Los Osos Basin or the Arroyo Grande Subbasin. The SLO Basin GSAs have developed a cooperative working relationship with the Los Osos Groundwater Basin — Basin Management Committee and the GSAs working in the Arroyo Grande Subbasin. Groundwater conditions near the borders with these basins will be monitored and shared. 31 Page 402 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 8.9.2.4 Effects of Minimum Thresholds on Beneficial Uses and Users The MT for Depletion of Interconnected Surface Water is defined to maintain historically observed groundwater elevations. The practical effect of this GSP for protecting against the Depletion of Interconnected Surface Water MTs is that it encourages minimal long-term net change in groundwater elevations in the vicinity of the Basin streams. Seasonal and drought cycle variations are expected, but during average conditions and over the long-term, beneficial users will have access to adequate volumes of water from the aquifer to service the needs of all water use sectors. The beneficial users of groundwater are protected from undesirable results. ricultural Land Uses and Users The water levels set as MTs are within the historical range of data, implying that surface water/groundwater interaction will be within historical norms. Therefore, existing agricultural operations are not expected to be affected by the Depletion of Interconnected Surface Water MTs. Urban Land Uses and Users Development of real estate along streams and creeks is generally constrained by prohibiting development in mapped floodplains in the Basin. Therefore, the Depletion of Interconnected Surface Water MTs are not anticipated to affect urban land users in the Basin. Domestic Land Uses and Users Development of real estate along streams and creeks is generally constrained by prohibiting development in mapped floodplains in the Basin. Therefore, the Depletion of Interconnected Surface Water MTs are not anticipated to affect urban land users in the Basin. Ecological Land Uses and Users. Groundwater dependent ecosystems would generally benefit from this MT. Maintaining groundwater levels close to within historically observed ranges will continue to support groundwater dependent ecosystems. More detailed mapping of GDEs, installation of gages in Edna Valley, and development of discharge rating curves for the San Luis Creek gages, all will clarify the effects of these MTs on ecological uses. 8.9.2.5 Relation to State, Federal, or Local Standards Agreements with NOAA mandate a minimum delivery for environmental flows of 1.6 MGD of effluent flow from the City Wastewater Treatment Plant located along San Luis Obispo Creek near the outlet of the Basin in San Luis Valley. SWRCB permit requirements with respect to outflow from Righetti Reservoir may impact flow conditions along West Corral de Piedras Creek. 8.9.2.6 Methods for Quantitative Measurement of Minimum Threshold The quantitative metric for assessing compliance with the Depletion of Interconnected Surface Water MTs is monitoring groundwater elevations at the three RMSs designated for this Sustainability Indicator (SLV-12, EV-01, EV-11). The approach for quantitatively evaluating compliance with the MT for reduction in groundwater storage will be based on evaluating groundwater elevations semi-annually. All groundwater elevations collected from the groundwater level monitoring network will be analyzed and averaged. 8.9.3 Measurable Objectives Similar to minimum thresholds, measurable objectives were defined using water level data based on the historical water level data observed in RMSs intended to monitor streamflow conditions. Measurable objectives for these wells are presented in Table 8-1 and Figures 8-4, 8-9, and 8-10. If future data from a 32 Page 403 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO more comprehensive surface water monitoring program documents quantitative estimates of stream flow depletion, those data may be used to re -define the measurable objectives for areas of interconnection. 8.9.3.1 Method for Quantitative Measurement of Measurable Objectives The measurable objectives are set based on maintaining current conditions of seasonal high water level elevations observed in the RMS wells during rainy periods. The quantitative method for assessing compliance with the MOs is monitoring of groundwater elevations at the selected RMSs. 8.9.3.2 Interim Milestones Interim milestones show how the GSAs anticipate moving from current conditions to meeting the measurable objectives. Interim milestones are set for each five-year interval following GSP adoption. MOs for the Depletion of Interconnected Surface Water are set at historically observed conditions of high groundwater elevations during wet climatic periods. Therefore, the interim milestones are defined to be identical to the water levels associated with the MOs. 8.10 MANAGEMENT AREAS Management areas are not established in the Basin. The GSAs and GSC members did not find it necessary to sub -divide the Basin into smaller management areas with specific administrative requirements. 33 Page 404 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO RMS SLV-19 (315112E-14C011 140 120 100 9 s0 60 3 40 20 Q Sustainable Management Criteria (§ 354.22) MEN MEN room MEN Ki 0 W I 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 CHRONICLOWERING OF GROUNIMAND49WTERER LEVELS REDUCTION OF GROU N 647LhT ER STORAGE �.�tiL i `r •i..�i 4,. J \ Figure 8-1 HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-19. 130 110 90 70 50 30 10 -10 -30 50 RMS SLV-16 (31S112E-10H03 ) Irl If ISM 0 1100110011001100 0 M■ 1980 1990 2000 2010 2020 2030 2040 CHRONIC LOWERING OF GROUNDWATER LEVELS REDUCTION OF 0 GROUNDWATER STORAGE Figure 8-2 HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-16. 34 Page 405 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 70 60 1985 SLV-09 (Pacific Beach Well 41) 1995 2005 2015 2025 2035 Sustainable Management Criteria (§ 354.22) LAND SUBSIDENCE CHRONIC LOWERING OF GROUNDWATER LEVELS REDUCTION GROUND4'JATERER STORAGE Figure 8-3. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-09. SLV-12 (31SJ12E-10DO3) 13a +IIIIIIIIIIIII6 INTER -CONNECTED 110 90 a V 70 c O 50 w a 30 10 3 -10 -30 r0 M9 - IOOtl MF•&iR 8S R Sa2ursaed ihihnesa - - - - - - - - - - - - - - - - - - - - +oase.�ed ■ IMs SURFACE WATER DEPLETIONS CHRONIC LOWERING OF GROUN HATER LEVELS REDUCTION OF GROUNDWATER STORAGE 1990 2000 2010 2020 2030 2040 ;`im� Figure 8-4. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS SLV-12. 35 Page 406 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 300 2S0 200 150 100 50 0 -50 i00 RMS EV-12 {315/13E-27M63 Sustainable Management Criteria (§ 354.22) CHRONIC LOWERING OF GROUNDWATER LEVELS REDUCTION OF GROUNDWATER STORAGE j —�} f�� CC 1 rr ,_ 'p 1 1990 2000 2010 2020 2030 2040 Figure 8-5. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-12. RMS EV-64 [31S/13E-19HO1 } 275 u a suAxe ummon 2 50 nso - 247 R 225 ! 200 175 D q50 }�S xlr - Sca k W v 125 l0U obse ved ■ M5 `160RSalurrted Thkimess 75 50 25 geprxt Ekwtari I+cvraxl 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 CHRONIC LOWERING OF GRDUNIAVATER LEVELS REDUCTION OF GROUNDWATER Q) STORAGE Figure 8-6. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-04 36 Page 407 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 250 200 150 a 100 so � a -5a -1oa -150 2d0 RMS EV-09 i315/13E-19RO3 j Sustainable Management Criteria (§ 354.22) MA M=1 ■ 1990 2000 2010 2020 2030 2040 CHRONIC LOWERING OF GROUNDV'dATER LEVELS REDUCTION OF 0 GROUNDWATER STORAGE Figure 8-7. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-09. RMS EV-16 (VRMWC #I) 340 320 309 280 260 240 4 a 220 w 244 ISO 160 9 140 120 xw so 60 i --�■ 1-• . . N N N N N N N N . u �a o 0 0 0 o v v v 4!1 O 4�i O l�ii O N 4 H 4 N p CHRONIC LOWERING OF GROUNDWATER LEVELS REDUCTION OF GRGU 0 GROl1NDV9WTERER STORAGE Figure 8-8. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-16. 37 Page 408 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 33a 320 310 300 o 290 ., 280 v 270 260 250 240 230 RMS EV-01 (31S/13E-16N01) Sustainable Management Criteria (§ 354.22) INTER -CONNECTED SURFACE WATER DEPLETIONS k � l cp 5 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 �1-� Figure 8-9. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-01. RMS EV-11(31Sj13E-29F06-CASGEM/Greengate) 280 260 a 240 m LaM SuRa[e EkreuM G 220 My • rn n 1200 a 180 MT. 177 H —Observed 1,60 ■ IMS 140 2010 2015 2020 2025 2030 2035 2040 INTER -CONNECTED SURFACE WATER �y DEPLETIONS Figure 8-10. HYDROGRAPH, MINIMUM THRESHOLD, AND MEASURABLE OBJECTIVE FOR RMS EV-11. 38 Page 409 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO REFERENCES Balance Hydrologics. 2008. Hydrology and Geology Assessment of the Pismo Creek Watershed, San Luis Obispo County, California. 2008. Blaney. 1963. Utilization of the Water of the Santa Ynez River Basin in Southern Santa Barbara County California, United Stated Deparment of Agriculture. 1963. -. 1933. Ventura County Investigation, Bulletin No. 46, California Deparment of Public Works, Division of Water Resources. 1933. Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. CIMS. 2019. Station 52, San Luis Obispo - Central Coast Valleys. 2019. City of San Luis Obispo. 2016.2015 Urban Water Management Plan. 2016. -. 2018. General Plan. 2018. -. 2015. Water Resources Status Report. 2015. -. 2000. Water Use Factors. 2000. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. -. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists. 2018. Groundwater Flow Analysis, Recycled Water Recharge Project, San Luis Valley Subarea, San Luis Obispo Valley Groundwater Basin. 2018. -. 2019. Optional Task 2.4B Geophysical Survey. 2019. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. -. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. -. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (IRWMP). 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2015. Consumptive Use Program Plus (CUP+) Model, in California Water Plan Update 2013, Volume 4. Reference Guide, Developed by DWR and UC Davis. 2015. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. 39 Page 410 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 1996. South Central Coast Land Use Survey. 1996. -. 1987. Southern Central Coast Land Use Survey, 1985. Morro Bay South 54-30 and San Luis Obispo 54-31 Survey Maps. 1987. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. -. 2016. Water Budget Best Management Practices for the Sustainable Management of Groundwater. 2016. -. 2002. Water Resources of the Arroyo Grande - Nipomo Mesa Area. 2002. EPA. 2008. Water Sense Factsheet - Indoor Water Use in the United States, EPA-832-F-06-004. 2008. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study. September. 1994. Fugro West and Cleath & Associates. 2002. Paso Robles Groudnwater Study, Final Report. 2002. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. Hall, C.A. 1979. Geologic map of the San Luis Obispo - San Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. -. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. ITRC. 2020. Official Cal Poly Precipitation Data, Cal Poly/NOAA Station Rain Gage. 2020. Johnson, A.I. 1967. Specific Yield - Compilation of Specific Yield for Various Materials, U.S. Geological Survey Water -Supply Paper 1662-D, prepared in cooperation with the California Deparment of Water Resources. 1967. National Land Cover Database. Multi -Resolution Land Characteristics Consortium. 2016. Multi -Resolution Land Characteristics Consortium. Rosenberg, L.I. 2001. Potential Aquifer Recharge Areas: Monterey County, California. s.l.: Monterey County Planning Department, 2001. San Luis Obispo County Deparment of Agriculture/Weights and Measures. 2019. Crop Surveys for San Luis Obispo Valley Groundwater Basin 2013-2018. 2019. San Luis Obispo County Department of Public Works. 2020. Andrews Street Bridge Stream Flow Gage 745. 2020. -. 2020. Gas Company Rain Sensor 3099. 2020. San Luis Obispo County Engineering Department. 1974. Hydrologic & Climatological Data, Seasons of 1970-71 & 1971-72. 1974. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. SWRCB. 1990. Ernest Righetti & Sons Application 28883, Decision 1627. 1990. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.1.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. Page 411 of 1183 SLO Basin Groundwater Sustainability Plan Sustainable Management Criteria (§ 354.22) County of SLO and City of SLO 41 Page 412 of 1183 DRAFT Chapter 9 - Projects and Management Actions Chapter 10 - Implementation Plan San Luis Obispo Valley Basin Groundwater Sustainability Plan Available for viewing in the June 21, 2021 Agenda Packet: June 16, 2021 Recommended the GSAs to receive and file for public comments: June 21, 2021 Available for public comments on www.slowaterbasin.com: June 22, 2021 Close of public comment period: July 22, 2021 Per the GSC's recommendation on June 21, 2021, GSP Draft Chapter 9 - Projects and Management Actions and Chapter 10 Implementation Plan will be distributed to the City and County GSAs to receive and file. This draft document is now posted on the web portal: www.slowaterbasin.com for public comments. Comments from the public are being collected using a comment form available at www.slowaterbasin.com by clicking on "Submit Comment". If you require a paper form to submit by postal mail, please contact your local Groundwater Sustainability Agency (GSA). All comments submitted will also be posted online for viewing. Page 413 of 1183 Draft Groundwater Sustainability Plan Chapter 9 and 10 — Projects and Management Actions and Implementation Plan forthe San Luis Obispo Valley Groundwater Basin Groundwater Sustainability Agencies Prepared by Ws c WATER SYSTEMS CONSULTING, INC. C'HG GE1 c Gsi co�s�icant5 T Stillwater Sciences WaterSoloNons,Inc. 6/14/2021 Page 414 of 1183 SLO Basin Groundwater Sustainability Plan Table of Contents County of SLO and City of SLO TABLE OF CONTENTS Tableof Contents........................................................................................................................................... i Listof Figures................................................................................................................................................ v Tables........................................................................................................................................................... vi Appendices.................................................................................................................................................. vii Listof Terms Used...................................................................................................................................... viii ExecutiveSummary....................................................................................................................................... 1 9 Projects and Management Actions (§ 354.44)..................................................................................... 2 9.1 Introduction.................................................................................................................................. 2 9.2 Overview of Potential Projects and Management Actions........................................................... 3 9.2.1 Project and Management Actions Development.................................................................. 3 9.2.1.1 Screening and Ranking of Projects................................................................................ 3 9.2.1.2 Summary of Projects.....................................................................................................3 9.2.2 Addressing Sustainability Indicators (§ 354.44 (1))..............................................................9 9.2.3 Overdraft Mitigation (§ 354.44 (2))...................................................................................... 9 9.3 Integrated Surface Water and Groundwater Modeling...............................................................9 9.4 Projects.......................................................................................................................................11 9.4.1 State Water Project for Agricultural Irrigation....................................................................11 9.4.1.1 Project Benefits (§ 354.44.5)....................................................................................... 12 9.4.1.2 Supply Reliability (§ 354.44.6)..................................................................................... 12 9.4.1.3 Project Costs (§ 354.44.8)........................................................................................... 13 9.4.1.4 Project Implementation (§ 354.44.4)..........................................................................13 9.4.1.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 13 9.4.1.6 Legal Authority (§ 354.44.7)........................................................................................ 14 9.4.1.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................14 9.4.1.8 Public Notice and Outreach (§ 354.44B)..................................................................... 14 9.4.2 City of SLO Recycled Water for Agricultural Irrigation........................................................16 9.4.2.1 Project Benefits (§ 354.44.5)....................................................................................... 16 9.4.2.2 Supply Reliability (§ 354.44.6)..................................................................................... 16 9.4.2.3 Project Costs (§ 354.44.8)........................................................................................... 17 9.4.2.4 Project Implementation (§ 354.44.4)..........................................................................17 9.4.2.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 18 9.4.2.6 Legal Authority (§ 354.44.7)........................................................................................ 18 9.4.2.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................18 Page 415 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 9.4.2.8 Public Notice and Outreach (§ 354.44B).....................................................................18 9.4.3 State Water Project Recharge Basin................................................................................... 18 9.4.3.1 Project Benefits (§ 354.44.5)....................................................................................... 19 9.4.3.2 Supply Reliability (§ 354.44.6).....................................................................................19 9.4.3.3 Project Costs (§ 354.44.8)........................................................................................... 19 9.4.3.4 Project Implementation (§ 354.44.4)..........................................................................19 9.4.3.5 Basin Uncertainty (§ 354.44.9d).................................................................................20 9.4.3.6 Legal Authority (§ 354.44.7)........................................................................................ 20 9.4.3.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................22 9.4.3.8 Public Notice and Outreach (§ 354.44B).....................................................................22 9.4.4 State Water Project to Golden State Water Company....................................................... 22 9.4.4.1 Project Benefits (§ 354.44.5)....................................................................................... 22 9.4.4.2 Supply Reliability (§ 354.44.6)..................................................................................... 23 9.4.4.3 Project Costs (§ 354.44.8)........................................................................................... 23 9.4.4.4 Project Implementation (§ 354.44.4)..........................................................................23 9.4.4.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 23 9.4.4.6 Legal Authority (§ 354.44.7)........................................................................................ 23 9.4.4.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................23 9.4.4.8 Public Notice and Outreach (§ 354.44B).....................................................................23 9.4.5 City of SLO Potable Water to Golden State Water Company ............................................. 25 9.4.5.1 Project Benefits (§ 354.44.5)....................................................................................... 25 9.4.5.2 Supply Reliability (§ 354.44.6)..................................................................................... 25 9.4.5.3 Project Costs (§ 354.44.8)........................................................................................... 25 9.4.5.4 Project Implementation (§ 354.44.4)..........................................................................25 9.4.5.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 26 9.4.5.6 Legal Authority (§ 354.44.7)........................................................................................ 26 9.4.5.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................26 9.4.5.8 Public Notice and Outreach (§ 354.44B).....................................................................26 9.4.6 Varian Ranch Mutual Water Company Arroyo Grande Subbasin Wells ............................. 26 9.4.6.1 Project Benefits (§ 354.44.5)....................................................................................... 27 9.4.6.2 Supply Reliability (§ 354.44.6)..................................................................................... 27 9.4.6.3 Project Costs (§ 354.44.8)........................................................................................... 27 9.4.6.4 Project Implementation (§ 354.44.4)..........................................................................27 9.4.6.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 27 9.4.6.6 Legal Authority (§ 354.44.7)........................................................................................ 27 ii Page 416 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 9.4.6.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................28 9.4.6.8 Public Notice and Outreach (§ 354.44B)..................................................................... 28 9.4.7 State Water Project to the Mutual Water Companies....................................................... 28 9.4.7.1 Project Benefits (§ 354.44.5)....................................................................................... 28 9.4.7.2 Supply Reliability (§ 354.44.6)..................................................................................... 28 9.4.7.3 Project Costs (§ 354.44.8)........................................................................................... 28 9.4.7.4 Project Implementation (§ 354.44.4)..........................................................................28 9.4.7.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 29 9.4.7.6 Legal Authority (§ 354.44.7)........................................................................................ 29 9.4.7.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................29 9.4.7.8 Public Notice and Outreach (§ 354.44.13)....................................................................29 9.4.8 Price Canyon Discharge Relocation..................................................................................... 29 9.4.8.1 Project Benefits (§ 354.44.5)....................................................................................... 30 9.4.8.2 Supply Reliability (§ 354.44.6)..................................................................................... 30 9.4.8.3 Project Costs (§ 354.44.8)........................................................................................... 30 9.4.8.4 Project Implementation (§ 354.44.4)..........................................................................30 9.4.8.5 Basin Uncertainty (§ 354.44.9d)................................................................................. 30 9.4.8.6 Legal Authority (§ 354.44.7)........................................................................................ 31 9.4.8.7 Permitting and Regulatory Processes (§ 354.44.3).....................................................31 9.4.8.8 Public Notice and Outreach (§ 354.44.13)....................................................................31 9.4.9 Modeling of Multiple Projects............................................................................................ 33 9.5 Management Actions.................................................................................................................. 35 9.5.1 Expand Monitoring Network...............................................................................................35 9.5.2 Groundwater Extraction Metering and Reporting Plan......................................................35 9.5.2.1 De Minimis Self-Certification...................................................................................... 35 9.5.2.2 Non -De Minimis Extraction and Reporting Program..................................................36 9.5.3 Demand Management Plan................................................................................................ 36 9.5.3.1 Water Conservation Measures................................................................................... 36 9.5.3.2 Irrigation Efficiency Improvements.............................................................................37 9.5.3.3 Volunteer Water Efficient Crop Conversion...............................................................39 9.5.3.4 Volunteer Land Fallowing........................................................................................... 39 9.5.3.5 Pumping Reductions................................................................................................... 39 9.6 Adaptive Management (§ 354.44A)............................................................................................40 10 Implementation Plan..........................................................................................................................41 10.1 GSP Implementation, Administration, and Management..........................................................41 Page 417 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table of Contents 10.1.1 Administrative Approach/Governance Structure...............................................................41 10.1.2 Implementation Schedule...................................................................................................41 10.1.3 Implementation Costs.........................................................................................................43 10.1.3.1 Administration and Finance........................................................................................43 10.1.3.2 Monitoring Network Implementation........................................................................43 10.1.3.3 Project Implementation..............................................................................................43 10.1.3.4 Reporting.....................................................................................................................44 10.1.4 Outreach and Communication............................................................................................44 10.2 Funding....................................................................................................................................... 44 10.2.1 GSP Implementation Funds................................................................................................44 10.2.2 Fee Study............................................................................................................................. 44 10.2.3 Grant/Low Interest Financing.............................................................................................44 10.3 Reporting.....................................................................................................................................45 10.3.1 Annual Reports....................................................................................................................45 10.3.1.1 General Information...................................................................................................45 10.3.1.2 Basin Conditions..........................................................................................................45 10.3.1.3 Implementation Progress............................................................................................45 10.3.2 Five -Year Evaluation Reports..............................................................................................47 10.3.2.1 Sustainability Evaluation.............................................................................................47 10.3.2.2 Plan Implementation Progress....................................................................................47 10.3.2.3 Reconsideration of GSP Elements...............................................................................47 10.3.2.4 Monitoring Network Description................................................................................47 10.3.2.5 New Information.........................................................................................................47 10.3.2.6 Regulations or Ordinances..........................................................................................48 10.3.2.7 Legal or Enforcement Actions.....................................................................................48 10.3.2.8 Plan Amendments.......................................................................................................48 10.3.2.9 Coordination...............................................................................................................48 10.3.2.10 Reporting to Stakeholders and the Public..................................................................48 11 References.......................................................................................................................................... 12 Appendices......................................................................................................................................... iv Page 418 of 1183 SLO Basin Groundwater Sustainability Plan List of Figures County of SLO and City of SLO LIST OF FIGURES Figure 9-1. Project Location Map.................................................................................................................. 8 Figure 9-2 Anticipated Future Availability of District SWP Supplies Based on the Historic Hydrologic Period(1922-2003)..................................................................................................................................... 13 Figure 9-3 SWP with In -Lieu Agricultural Pumping Reduction - 1,000 AFY — Project Scenario 1 ...............15 Figure 9-4. SWP Recharge Basin — 500 AFY — Project Scenario 2............................................................... 21 Figure 9-5 SWP Purveyor In -Lieu Pumping Reduction — GSWC = 200 AFY, VRMWC & ERMWC = 50 AFY — ProjectScenario 3....................................................................................................................................... 24 Figure 9-6. Relocation of Price Canyon Discharge Point — 500 AFY............................................................ 32 Figure 9-7Model Results from the Combined Modeled Project Scenarios — Project Scenario 5 ...............34 Figure 10-1. SLO Basin GSP Implementation Schedule...............................................................................42 v Page 419 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Tables Table 9-1. Initial Project Screening Evaluation Criteria................................................................................. 5 Table 9-2. Project Evaluation Scoring Results............................................................................................... 6 Table 9-3 Projects and Management Actions Strategies.............................................................................. 7 Table 9-4 Summary of Project and Management Action Benefits and Impacts on Sustainability Indicators. ...................................................................................................................................................................... 9 Table 9-5. Consumptive Use of Applied Water and Total Irrigated Acreage by Land Use/Land Cover Type .................................................................................................................................................................... 39 Table 10-1 GSP Implementation Costs(2022-2027)...................................................................................46 vi Page 420 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO APPENDICES Appendices Appendix A - City of San Luis Obispo Resolution to form GSA Appendix B - County of San Luis Obispo Resolution to form GSA Appendix C - Memorandum of Agreement — Preparation of GSP Appendix D Communications and Engagement Plan Appendix E Surface Water/Groundwater Modeling Approach Appendix F Stakeholder Workshop Summary — Building a Shared Vision for a "Sustainable SLO Basin" Appendix G Sustainable Goal Setting Workshop Appendix H Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin Appendix I Groundwater Level Measurement Procedures for the San Luis Obispo Valley Groundwater Basin GSP Appendix J Streamflow Measurement in Natural Channels Appendix K Data Management Plan Appendix L Response to Public Comments vii Page 421 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used LIST OF TERMS USED Abbreviation Definition AB Assembly Bill ADD Average Day Demand AF Acre Feet AFY Acre Feet per Year AMSL Above Mean Sea Level Basin Plan Water Quality Control Plan for the Central Coast Basin Cal Poly California Polytechnic State University CASGEM California State Groundwater Elevation Monitoring program CCR California Code of Regulations CCRWQCB Central Coast Regional Water Quality Control Board CCF One hundred cubic feet CCGC Central Coast Groundwater Coalition CDFM Cumulative departure from the mean CDPH California Department of Public Health CIMIS California Irrigation Management Information System City City of San Luis Obispo County County of San Luis Obispo CPUC California Public Utilities Commission CPWS-52 Cal Poly Weather Station 52 CRWQCB California Regional Water Quality Control Board CWC California Water Code DDW Division of Drinking Water Du/ac Dwelling Units per Acre DWR Department of Water Resources EPA Environmental Protection Agency ERMWC Edna Ranch Mutual Water Company ETo Evapotranspiration EVGMWC Edna Valley Growers Ranch Mutual Water Company °F Degrees Fahrenheit FAR Floor Area Ratio FY Fiscal Year GAMA Groundwater Ambient Monitoring and Assessment program GHG Greenhouse Gas GMP Groundwater Management Plan GPM Gallons per Minute GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Commission GSP Groundwater Sustainability Plan GSWC Golden State Water Company IRWMP San Luis Obispo County Integrated Regional Water Management Plan kWh Kilowatt -Hour LUCE Land Use and Circulation Element LUFTs Leaky Underground Fuel Tanks MAF Million Acre Feet viii Page 422 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO List of Terms Used Abbreviation Definition MCL Maximum Contaminant Level MG Million Gallons MGD Million Gallons per Day Mg/L Milligrams per Liter MOA Memorandum of Agreement MOU Memorandum of Understanding MWR Master Water Report NCDC National Climate Data Center NOAA National Oceanic and Atmospheric Administration NWIS National Water Information System O&M Operations and Maintenance PPWTP Polonio Pass Water Treatment Plant RW Recycled Water RWQCB Regional Water Quality Control Board SB Senate Bill SGMA Sustainable Groundwater Management Act SGMP Sustainable Groundwater Management Planning SGWP Sustainable Groundwater Planning SLO Basin San Luis Obispo Valley Groundwater Basin SLOFCWCD San Luis Obispo Flood Control and Water Conservation District SCML Secondary Maximum Contaminant Level Sol Sphere of Influence SNMP Salt and Nutrient Management Plan SWP State Water Project SWRCB California State Water Resources Control Board TDS Total Dissolved Solids TMDL Total Maximum Daily Load USGS United States Geological Survey USFW United States Fish and Wildlife Service USTs Underground Storage Tanks UWMP Urban Water Management Plan UWMP Act Urban Water Management Planning Act UWMP Guidebook Department of Water Resources 2015 Urban Water Management Plan Guidebook VRMWC Varian Ranch Mutual Water Company WCS Water Code Section WMP Water Master Plan WPA Water Planning Areas WRF Water Reclamation Facility WRCC Western Regional Climate Center WRRF Water Resource Recovery Facility WSA Water Supply Assessment WTP Water Treatment Plant WWTP Wastewater Treatment Plant ix Page 423 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO EXECUTIVE SUMMARY This section to be completed after GSP is completed Executive Summary Page 424 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9 PROJECTS AND MANAGEMENT ACTIONS (§ 354.44) 9.1 INTRODUCTION This chapter describes the Projects, Management Actions and Adaptive Management information that satisfies Sections 354.42 and 354.44 of the SGMA regulations. These projects, actions, and their benefits are intended to help achieve sustainable management goals in the Basin. Under the Regulations, § 354.44, the Groundwater Sustainability Plan (GSP, Plan) is to include the following: • Each Plan shall include a description of the projects and management actions the Agency has determined will achieve the sustainability goal for the basin, including projects and management actions to respond to changing conditions in the basin. Each Plan shall include a description of the projects and management actions that include the following: o A list of projects and management actions proposed in the Plan with a description of the measurable objective that is expected to benefit from the project or management action. The list shall include projects and management actions that may be utilized to meet interim milestones, the exceedance of minimum thresholds, or where undesirable results have occurred or are imminent. The Plan shall include the following: ■ A description of the circumstances under which projects or management actions shall be implemented, the criteria that would trigger implementation and termination of projects or management actions, and the process by which the Agency shall determine that conditions requiring the implementation of particular projects or management actions have occurred. ■ The process by which the Agency shall provide notice to the public and other agencies that the implementation of projects or management actions is being considered or has been implemented, including a description of the actions to be taken. o If overdraft conditions are identified through the analysis required by Section 354.18, the Plan shall describe projects or management actions, including a quantification of demand reduction or other methods, for the mitigation of overdraft. o A summary of the permitting and regulatory process required for each project and management action. o The status of each project and management action, including a timetable for expected initiation and completion, and the accrual of expected benefits. o An explanation of the benefits that are expected to be realized from the project or management action, and how those benefits will be evaluated. o An explanation of how the project or management action will be accomplished. If the projects or management actions rely on water from outside the jurisdiction of the Agency, an explanation of the source and reliability of that water shall be included. o A description of the legal authority required for each project and management action, and the basis for that authority within the Agency. o A description of the estimated cost for each project and management action and a description of how the Agency plans to meet those costs. o A description of the management of groundwater extractions and recharge to ensure that chronic lowering of groundwater levels or depletion of supply during periods of drought is offset by increases in groundwater levels or storage during other periods. 2 Page 425 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO • Projects and management actions shall be supported by best available information and best available science. • An Agency shall take into account the level of uncertainty associated with the basin setting when developing projects or management actions. 9.2 OVERVIEW OF POTENTIAL PROJECTS AND MANAGEMENT ACTIONS 9.2.1 Project and Management Actions Development The projects and management actions concepts were developed over a series of working sessions with GSA staff, meetings with GSC members and in six public GSC meetings between December 9, 2020 and June 21, 2021. The projects and management actions are focused in the Edna Valley (Figure 9-1) where the overdraft was documented in Chapter 6 Water Budget. The effectiveness of the projects and management actions will be assessed by the ability to mitigate undesirable results such as groundwater level declines in the Edna Valley Representative Monitoring Sites (RMS) described in Chapter 8 Sustainable Management Criteria. 9.2.1.1 Screening and Ranking of Projects An initial screening of the projects was performed using the evaluation criteria shown in Table 9-1. The Evaluation Criteria developed collaboratively with the GSC members were applied to the list of projects deliberated by the GSA Staff, GSC members, and the public. The results of the initial screening and ranking are displayed in Table 9-2. The scoring of each project was weighted to better represent the ease/likelihood of implementation and the impacts of the project on the sustainability goals described in Chapter 8. 9.2.1.2 Summary of Projects Table 9-3 provides a summary of the projects and management actions considered in this GSP. The table shows the status, timing for implementation (years), capital costs ($), annual Operations and Maintenance (0&M) ($/Year), quantity of water delivered (AFY), and the unit cost ($/AFY) for each project and management action. The projects discussed in this GSP are centered around supplemental water sources that could be brought into the SLO Basin to mitigate the overdraft. The projects considered supplemental water from three sources all of which have existing conveyance infrastructure within or in close proximity to the Basin; State Water Project, City of SLO recycled water, and Price Canyon discharge. The project costs included in this GSP were prepared in conformance with industry practice and, as planning level cost opinions, and ranked as a Class 4 Conceptual Opinion of Probable Construction Cost as developed by the Association for the Advancement of Cost Engineering (Association for the Advancement of Cost Engineering, 2011). The AACE classification system is intended to classify the expected accuracy of planning level cost opinions and is not a reflection on the effort or accuracy of the actual cost opinions prepared for the GSP. According to AACE, a Class 4 Estimate is intended to provide a planning level conceptual effort with an accuracy that will range from -30% to +50% and includes an appropriate contingency for planning and feasibility studies. The conceptual nature of the projects and associated costs presented in this Chapter are based upon limited design information available at this current stage of the projects. At this planning -level stage, two percentages were applied to the estimated construction costs, 30% for construction contingency and 25% for implementation costs (which incorporates anticipated Design, Construction Management, and Environmental and Construction Engineering costs). In order to estimate annual payments, a loan period of 30 years at a 5% interest rate was assumed. The $/AFY values were calculated using the total annual cost, which include capital repayment and operations and maintenance costs, divided by the estimated yield from each project, see Section 9.4 for further detail. It is important to 3 Page 426 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO note that the cost estimates shown in Table 9-3 do not include the cost of the water as the costs to purchase the water are subject to negotiation between the supplier and the purchasing party. The projects were further evaluated with the integrated model to quantify the benefit of the projects respect to the SMCs in the Edna Valley. Model results are described in more detail in Section 9.4. n Page 427 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO Table 9-1. Initial Project Screening Evaluation Criteria Criteria Scoring 1- <250 AFY 2- 250-500 AFY Quantity of Water 3- 500-750 AFY 4- 750-1000 AFY 5- > 1,000 AFY 1->$5M Capital Cost 3- $2,500,000 5- $0 1- >$4,000/AFY 2- $3,000 - $4,000/AFY Water Cost 3- $2,000 - $3,000/AFY 4- $1,000 - $2,000/AFY 5- < $1,000/AFY 1- >$2,000/AFY 2- $1,000 - $2,000/AFY O&M Cost 3- $500 - $1,000/AFY 4- $100 - $500/AFY 5- < $100/AFY 1- Higher TDS to ambient groundwater GW Water Quality Impact 3- Equivalent TDS than ambient groundwater 5- Lower TDS than ambient groundwater 1- Highly variable Reliability/Resiliency 3- Moderately reliable 5- Highly reliable 1- > 10 years 2- 7 years Timeline to Implement 3- 5 years 4- 3 years 5- < 1 year 1- Significant regulatory, environmental, political, or social challenges 2- Feasibility/Complexity 3- Potential significant regulatory, environmental, political, or social challenges 4- 5- Limited regulatory, environmental, political, or social challenges 1- Detrimental Environmental impacts Environmental Impacts 3- Neutral Environmental impacts 5- Beneficial Environmental impacts 1- Detrimental Socioeconomic impacts Socioeconomic Impacts 3- Neutral Socioeconomic impacts 5- Beneficial Socioeconomic impacts 1- Limited grant funding opportunities Eligible for Grant Funding 3- Moderate grant funding opportunities 5- Significant grant funding opportunities 1- Minimal Effect on Groundwater Levels Groundwater Level Benefit 3- Average Effect on Groundwater Levels 5- Highest Effect Groundwater Levels Page 428 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table 9-2. Project Evaluation Scoring Results Projects and Management Actions (§ 354.44) Weighting Factor 3 2 2 2 1 1 1 2 1 1 1 4 LL U1 v U C LL C m Projects and v �, CO v v a CL E a, Management U U U +' is a) E o F +� (D a', U H Actions Description O ° a`, ' o `� T o L L ':t Q U o2f +�+ SZ 0 +�� 2i H L O O O U- W N w O i U SWP to Ag Irrigation Connection to SWP to offset Ag groundwater pumping through direct delivery of SWP Water 1000 5 2 3 4 3 3 3 3 4 4 3 73 SWP Recharge Connection to SWP to provide water for groundwater recharge 500 3 2 3 4 5 3 3 3 3 4 4 4 71 City of SLO Potable Connection to City of SLO potable water system to offset Golden Water to GSWC State Water Company groundwater pumping through direct delivery 400 2 4 1 4 5 5 4 3 4 3 3 4 70 City of SLO Recycled Connection to City of SLO Recycled Water System to offset Ag Water to Ag groundwater pumping through direct delivery 500- 3 3 1 4 4 5 4 4 3 4 4 3 69 Irrigation 700 SWP to GSWC Connection to SWP project to offset GSWC groundwater pumping through direct delivery of SWP Water 400 2 2 3 4 5 3 4 3 3 4 4 4 69 Price Canyon Relocation of Sentinel Peak Produced Water Discharge location to Discharge Relocation upper Corral de Piedra Creek or direct delivery to agriculture 500 2 2 5 4 5 5 4 2 4 3 4 3 69 Varian Ranch MWC Connection to Varian Ranch MWC wells in Arroyo Grande Subbasin AG Subbasin Wells to offset Varian Ranch groundwater pumping through direct delivery 35 3 5 4 3 4 4 3 3 4 4 3 67 of imported groundwater SWP to Mutual Connection to SWP to offset Edna and Varian Ranch MWC Water Companies groundwater pumping through direct delivery of SWP Water 200 4 3 4 5 3 3 3 3 4 4 3 65 East Corral de Piedra Capture of high flow stormwater in East Corral de Piedra Creek and Stormwater Capture percolation in a recharge basin 50 3 5 4 5 1 4 3 5 3 5 2 64 and Recharge Page 429 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO Table 9-3 Projects and Management Actions Strategies Projects and Implementation Annual Total Annual Quantity Unit Cost Management Status Timing Capital Cost Capital O&M Annual of Water ($/AF)l Actions Payment _ Payment (AF) Feasibility study: 0 to SWP to Ag Not begun 1 years $ 890,000 $ 58,000 $ 5,000 $ 63,000 1,000 $ 60 Irrigation yet Design/Construction: 1 to 5 years Evaluated as City of SLO part of the Feasibility study: 0 to Recycled Water City of SLO 1 years $ 1,004,000 $ 65,000 $ 88,000 $153,000 600 $ 260 Recycled Design/Construction: to Ag Irrigation Water Study 1 to 3 years (2017) Feasibility study: 0 SWP Recharge Not begun to 1 years $ 3,624,000 $ 236,000 $ 101,000 $ 337,000 500 $ 670 yet Design/Construction: 1 to 5 years Feasibility study: 0 SWP to GSWC Not begun to 1 years $ 2,685,000 $ 175,000 $ 17,000 $ 192,000 200 $ 960 yet Design/Construction: 1 to 5 years City of SLO Feasibility study: 0 Potable Water to Not begun to 1 years $ 1,739,000 $ 127,000 $ 14,000 $ 127,000 200 $ 640 yet Design/Construction: GSWC 1 to 3 years Varian Ranch Feasibility study: 0 MWC AG Not begun to 1 years $ 2,701,000 $ 176,000 $ 34,000 $ 210,000 50 $ 4,200 Subbasin Wells Yet Design/Construction: 1 to 3 years Feasibility study: 0 SWP to Mutual Not begun to 1 years $ 835,000 $ 54,000 $ 5,000 $ 59,000 50 $ 1,180 Water Companies yet Design/Construction: 1 to 5 years Price Canyon Mitigated Feasibility study: 0 Discharge Negative Dec to 1 years $ 4,909,000 $ 319,000 $ 56,000 $ 375,000 500Z $ 750 Relocation Completed in Design/Construction: 2015 1 to 3 years East Corral de Feasibility study: 0 Piedra Stormwater Not begun to 1 years $ 3,169,000 $ 206,000 $ 101,000 $ 307,000 50 $ 6,140 Capture and Yet Design/Construction: Recharge 1 to 3 years Groundwater Not begun Extraction yet 1 year Metering Plan Demand Not begun Management As needed Strategies yet 1. Does not include the cost of the water. 2. Quantity of water at the discharge point. Page 430 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Projects and Management Actions (§ 354.44) Explanation _ MOA Participating Parties "t j r ` W "' Edna Valley Growers a MWC i4 t, Edna Ranch MWC - East r' Golden Stale WC -Edna Varian Ranch MWC i, Groundwater Sustainability Agencies �• San Luis Obispo Water .� r c. ♦ . �- ' , Department City of SLO '' ® GSof san Luis Obispo Recycled Water <`. t for Ag Irrigation ti<� ,•" •i - 4ty- County of San Luis Obispo GSA r r '— N �r ,., ''• •' S Surface Water Sources SWP forAg Irrigation ^ �. Lakes and Reserviors Surface Water ' City of SLO �SWP for GSWCo f ,4 Potable Water to ? J GSWCo F _ •` �,r • — `,�1 iii _ x Explanation SWP for Project Infrastructure Recharge Conveyance Pipeline SWPTurnouti-ti i • Discharge Point _ Lske�-- I` .. SWP for y rice Canyon MWCS 1 ❑P Proposed Recharge Site Discharge i Existing Infrastructure + 4j• _ Relocation • �. VRMWC • Discharge Point -Z AG Sub - - `i Basin Coastal Branch SWP r l'�I �a `1 Wells ' Recycled Water Pipeline If _ tar E rF,a:r=75, JSDA, U5G5, Aero G i.. and che'�IS L=_er Pmpared for: r.r References: NOfes: p r`I Project Ota ion a 1qI 10 DavL'errrz� 1 in. 1.1 mi Roeuo�r., M1lncalor Auxiliary Spr�ere b Merca[o�Hur y p re 12 0 03]5 0.75 San Luis Dbisoo Veffey 8asn �5r� �- GraunQwater Sustainability Plan Foe non.: r�a�res� proi.o:s �pano�Map_�2 0 o.s i 2 s. Figure9-1 Figure 9-1. Project Location Map 8 Page 431 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.2.2 Addressing Sustainability Indicators (§ 354.44 1 Table 9-4 shows the project and management action benefits and impacts on specific sustainability indicators and associated measurable objectives and minimum thresholds. Table 9-4 Summary of Project and Management Action Benefits and Impacts on Sustainability Indicators. SWPtoAg Irrigation Increases water levels inthe Edna Valleytoavoid minimumthresholds i Yes .. . .,,...., l ........... .... ...... „ .. ....,. Increases water levels In the Edna Valleyto avoid minimumthresholds City of SLO Recycled Water to Ag Irrigation _ Yes Supplemental Waterto Edna Valley , SWP Recharge Increases water levels in the Edna Valley to avoid minimumthresholds 1 Yes . ........ SWPto GSWC Reduces localized groundwater production 1 _ Yes Supplemental Watertothe Edna Valley O .. ....... . ....... ..... , .... .... , .. ..,, „ ....,....,. Reduces localized groundwater production City of SLO Potable Water to 65WC Yes Supplemental Water tothe Edna Valley Reduces localized groundwater production Varian Ranch MWCAGSubbasin Wells Yes Supplemental Water tothe Edna Valley Reduces localized groundwater production SWPto Mutual Water Companies Yes Supplemental Water tothe Edna Valley 1 _ Increases recharge tothe Edna Valley Price Canyon Discharge Relocation - Yes Increases streamflow in West Corral de Piedrasfor Steelhead .... ..... ..... ... ... ..... . East Corral de Pledra Stormwater Capture and Increased Recharge to the Edna Valley Yes Recharge .. ............ ... .... .... ,,.... ,,.... .... . ...... .... , .... .... , .... .... ,...... .... ,,.... „ .. ...,. Improve understanding ofthe Basin Groundwater Extraction Metering Plan No Abilityto managethe Basin Reduces groundwater production inthe Edna Valley Voluntary Fallowing of Agricultural Land Yes improved Irrigation Efficiency Reduces groundwater production In the Edna Valley Limited Notes: OChronic Lowering of Groundwater Levels Reduction of Groundwater Storage Depletion of Interconnected Surface Water Degradation of Groundwater Quality 9.2.3 Overdraft Mitigation (§ 354.44 (2)) The proposed projects and management actions are intended to maintain groundwater levels above minimum thresholds through in -lieu pumping reductions or increased recharge. Overdraft is caused when pumping exceeds recharge and inflows in the Basin over a long period of time. Improving the management of groundwater in the Basin will help to mitigate overdraft. 9.3 INTEGRATED SURFACE WATER AND GROUNDWATER MODELING As part of the development of this GSP, the GSAs incorporated the development of an integrated groundwater -surface water model of the Basin. A brief overview of the development and application of the model is presented herein. This discussion is not intended to be complete; more detailed documentation of the model is included in Appendix E, Surface Water/Groundwater Modeling Documentation. The integrated model was developed using GSFLOW, a modeling code developed and maintained by the United States Geological Survey (USGS). GSFLOW incorporates two existing USGS modeling codes under a single structure. The first is the Precipitation Runoff Modeling System (PRMS), which models rainfall, plant Rl Page 432 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO uptake, evapotranspiration, and runoff to streams, using a water budget approach applied to a gridded domain of the model area. The second is MODFLOW, which simulates groundwater flow and surface water/groundwater interaction in the aquifers of the model area. GSFLOW operates by first running PRMS, using climatological input and daily time steps to calculate the movement of rainfall that falls onto the Basin area through plant canopy, root zone, runoff to streams, and deep percolation to the groundwater environment. GSFLOW then transmits necessary data to MODFLOW (e.g., streamflow, deep percolation, etc.) at times and locations significant to the simulation of groundwater flow for the completion of the GSFLOW run. The areal model grid was established utilizing 500-foot square model grid cells that cover the entire contributing watershed of the Basin. The vertical grid was discretized into three layers to correspond to the three water bearing formations in the Basin (Alluvium, Paso Robles Formation, and Pismo Formation). The bedrock in the contributing watershed area was also discretized into three layers so that lateral hydraulic communication could be simulated between the bedrock and all three formations in the Basin. A historical calibration period from water years 1987 through 2019 was selected to correspond to the period of the historical water budget analysis documented in Chapter 6 of this GSP. The pumping estimates developed in the water budget analysis were used in the model calibration runs. Surface water flow data is unavailable for creeks in either the San Luis Valley or Edna Valley, but flow estimates were made for San Luis Obispo Creek based on flow stage or height data from the City's gages. The PRMS model was calibrated to achieve acceptable results for peak flow and flow volume on San Luis Obispo Creek. The MODFLOW model was calibrated to achieve acceptable results for groundwater elevations at wells in the Basin. The model calibration was found to meet industry criteria of a relative error of less than 10% (relative error is the mean error divided by the range of observed groundwater elevations). Therefore, the model was judged to be appropriate to perform predictive simulations to assess the impacts of proposed projects and management actions on water levels at RMS in the Basin. The model was applied to evaluate the GSP projects and management actions using the following methodology. To maintain continuity of results between the historical calibration period and the predictive period, each simulation was run continuously from the historical calibration period through the end of the predictive simulation period, from water years 1987 through 2045. (The SGMA planning ends in 2042, but the model was run through 2045 to make sure model results were stable at the end of the predictive period; model results are presented for the end of the SGMA planning period). The 1995-2019 pumping time series that was developed in the water budget analysis and used in the MODFLOW historical calibration was repeated for the predictive simulation period. Likewise, the climatological time series data used as input for PRMS historical calibration was also repeated for the predictive simulation period. Thus, the pumping and climatological conditions for the predictive simulations replicated the observed conditions from 1995-2019, including the recent drought period. It is assumed that there will be no significant increase in agricultural pumping or acreage during this time period. In order to assess the effect that a simulated project would have on groundwater elevations in the Basin, the following methodology was used. A baseline scenario was simulated in which no projects or management actions occurred. Pumping and climate conditions were repeated for the recent time series as previously discussed. Then a project scenario was incorporated in which a specific project or management action was represented in the model, either through reduction of pumping or introduction of a new source of recharge, as appropriate. The modeled RMS hydrographs for the baseline scenario and the project 10 Page 433 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO scenario are then plotted on the same chart, so the effect of the project can be assessed by the difference in water levels between the baseline and project scenario over the predictive period of the project implementation. The projects discussed herein were represented with only the project under consideration represented in the model, in order to quantify the effect of the individual project discussed. It is likely that more than one of these projects will be required to achieve sustainability, which will be evaluated later in this Chapter. Four separate project scenarios were modeled. However, some of these project model scenarios are intended to represent multiple projects as described in the following sections, but with different options for source water. It is assumed that the groundwater pumping reductions in the modeled project scenarios are offset by supplemental water supplies. For example, one of the project scenarios simulates a 1,000 AFY reduction in agricultural pumping. This reduction could conceivably be offset through import of State Water Project (SWP) water, short-term delivery of City of San Luis Obispo recycled water, or direct transfer of future Sentinel Peak effluent water to agriculture. So, this single model simulation could potentially represent the effects of more than one project, or a combination of projects, depending on the ultimate disposition and feasibility of obtaining the various possible sources of water or implementation of management actions. When this is the case, it will be noted in the text of the specific project descriptions. Additionally, a final project scenario was run in which four projects are represented simultaneously. 9.4 PROJECTS 9.4.1 State Water Project for Agricultural Irrigation The Coastal Branch of the SWP conveys water from the California Aqueduct to San Luis Obispo and Santa Barbara Counties (Figure 9-1). The California Aqueduct is operated by the California Department of Water Resources (DWR). The Coastal Branch provides water to two SWP Contractors: the Santa Barbara County Flood Control and Water Conservation District (via the Central Coast Water Authority (CCWA), a Joint Powers Authority) and the San Luis Obispo County Flood Control and Water Conservation District (District). The CCWA owns, operates, and maintains the Polonio Pass Water Treatment Plant (PPWTP) and operates the portion of the Coastal Branch that is downstream of Polonio Pass. The Coastal Branch transects the Edna Valley subarea and runs along Orcutt Road as shown in Figure 9-1. This project includes the construction of a new turnout to the Coastal Branch along Orcutt Rd south of the Energy Dissipation Valve and 200 feet of 10-inch pipeline to connect to the existing Edna Valley Growers Mutual Water Company distribution system. The project would allow for approximately 1,000 AFY of SWP water based on the availability and cost of SWP water, and will offset an equivalent amount of the irrigation demands currently met by groundwater. The SWP water is a treated water supply and may require dechlorination before being used for agricultural purposes. SWP water for the SLO Basin could be purchased from 1) District subcontractors that receive their SWP water through Lopez and Chorro Valley pipelines, 2) Santa Barbara County Participants or 3) a portion of the District's unsubscribed Table A amount (14,463 AFY). In the first two scenarios the purchaser would hold a sub -agreement with an existing subcontractor and not have a direct relationship with District. The third scenario would require the purchaser to become a new subcontractor to the District. The recent adoption of the Water Management Tools Amendment to the SWP Contracts by the District and the Santa Barbara County Flood Control and Water Conservation District (SBCWCFCD) presents new opportunities for obtaining SWP water supply and delivery capacity to Edna Valley. 11 Page 434 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.1.1 Project Benefits (§ 354.44.5) In order to assess this project's benefits to water levels in the aquifer and effect on sustainability of the Basin, a project scenario was simulated using the integrated GSFLOW model developed as part of the GSP efforts. A baseline simulation was performed in which agricultural pumping and climatological conditions for the predictive time period 2021-2045 was defined as a repetition of the time series used for 1995-2020. As a reminder, agricultural pumping in Edna Valley ranged from about 2,700 AFY to 4,200 AFY during this period. The model was run continuously for the time period from water years 1987 through 2045. Annual agricultural pumping estimates for San Luis Valley and Edna Valley developed during the preparation of the water budget (Chapter 6) were used, and the amounts were distributed among agricultural wells identified from County records. This project simulation assumes that 1,000 AFY of SWP water is available for agriculture to offset irrigation supply currently supplied by groundwater. For the predictive time period, agricultural pumping was reduced by 1,000 AFY in Edna Valley for the period starting in 2026. (These reductions were not applied to San Luis Valley, because no water level declines have been observed in that area.) This assumes it will take five years to implement the project or combination of projects required to make up the water for the pumping reduction. The 1,000 AFY in -lieu pumping reduction was distributed equally among all identified agricultural wells starting in 2026. Figure 9-3 displays the baseline and Project Scenario 1 hydrographs for this project for the four Edna Valley wells identified as the RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator. This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 5 feet at EV-04 to 31 feet at EV-16. (It should be noted that it is recognized that some model results in the vicinity of RMS EV-04 seem anomalous; the well at this location is relatively insensitive to changes in pumping, and the magnitude of the seasonal and drought water level fluctuations is not fully captured. This was identified in the model documentation as an area where the model may be improved, but in general the model results are instructive. In addition, earlier model runs prior to the final calibration displayed less improvement of water levels at EV-16; some re -distribution of agricultural pumping locations was incorporated in the final calibration run, which had an impact on model results at this RMS. 9.4.1.2 Supply Reliability (§ 354.44.6) The latest estimates of anticipated SWP availability under future conditions are included in the Department of Water Resources 2019 SWP Delivery Capability Report (DWR, 2019). The 2019 DCR anticipates approximately 58% of the District's and 59% of the SBCFCWCD's Table A and other contract amounts will be available on average under anticipated future conditions. These estimates are based on outputs from the CALSIM-2 Operations model (DWR, 2019). However, the availability of these SWP water supplies will be variable year by year based on hydrologic conditions. The historical delivery of Annual Allocation from the SWP ranges from 5% to 100% of the contracted amount. The anticipated amounts of SWP available to the District on an annual basis from the recent Water Management Tools study (CCWA, 2021) are shown in Figure 9-2. The CALSIM-2 Model projects future SWP supply availability under current operating conditions and constraints over the historic hydrologic period from 1922 to 2003. Carry-over water represents SWP water not used the previous year that is made available for use the following year by a SWP Contractor. Article 21 Water represents water above a Contractor's Table A allocation that could be available in a given year. 12 Page 435 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 60,000 ■TableAAmeunts ■CarryarerWater ■Artirle2lWater 50,000 A0, a 30,000 CL {/1 EL 2 0, 000 10,000 to .n W *+ v r+ o m 4o m rw .n W .+ W M o ff� YD m -+ a M o m .a .i .a .a .i .y .y w .i ra ry Figure 9-2 Anticipated Future Availability of District SWP Supplies Based on the Historic Hydrologic Period (1922-2003) Given the variable availability of SWP supplies, a project to deliver 1,000 AFY of SWP water to Edna Valley would likely need to be sized to accommodate greater than 1,000 AFY during wet years to balance out lower delivery amounts during dry years. Alternatively, contracts for the purchase of SWP could be structured to ensure a minimum delivery of 1,000 AFY of SWP water (e.g., purchasing Drought Buffer or more Table A Allocation or supply than delivery capacity) to provide a higher level of reliability for the SWP. However, to incorporate this enhanced reliability would likely increase the costs of the SWP supplies. For the purposes of the initial project level evaluation include in this GSP the capacity to deliver and availability of water were assumed to be a constant 1,000 AFY. 9.4.1.3 Project Costs (§ 354.44.8) The estimated capital cost to construct a turnout off from the Coastal Branch Pipeline and infrastructure to connect to the existing Edna Valley Growers Mutual Water Company distribution system is approximately $890,000 equating to an annual payment of $63,000 and a unit cost of $60/AF. These costs do not include the cost to purchase SWP or the work required to negotiate a contract with the District or District subcontractors. 9.4.1.4 Project Implementation (§ 354.44.4) Investigating the use of SWP as a supplemental water source would occur within the first year of implementation. Following the recommendations of the feasibility study, negotiations to acquire SWP from the identified sellers could take up to 5 years. The design and construction of the turnout and pipeline could occur concurrent with the negotiations and occur within 5 years. 9.4.1.5 Basin Uncertainty (§ 354.44.9d) The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the 13 Page 436 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.1.6 Legal Authority (§ 354.44.7) California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water, and privileges. The GSAs have the legal authority to conduct a feasibility study into the use of SWP as a supplemental water supply for the SLO Basin. Following the recommendation from the feasibility study the project could be implemented by the GSAs, GSC members or other parties. 9.4.1.7 Permitting and Regulatory Processes (§ 354.44.3) No permits or regulatory processes would be necessary for development of the feasibility study. However, implementation of this project will likely require a California Environmental Quality Act (CEQA) environmental review process and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require National Environmental Policy Act (NEPA) documentation. A new connection or turnout infrastructure requires coordination and agreements with the District, CCWA, and DWR. 9.4.1.8 Public Notice and Outreach (§ 354.4413) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 14 Page 437 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Ev-o4 250 MO E = zz5 w zoo s ° 175 I50 MT 7T, T o to o v� a w S EV-09 I EV-13 I zso 225 200 r 175 EV 1 1a O 1� � 150 I 225 EV-04: 0�99LE¢P'A", - C e 100 d` sc } is 9� G° as 4z de A 225 I 200 V zk 175 - MO 150 S 6 125 O 3 x 100 71 MT I .�.. S MO egos ei. Mi I EV-13 Prepared for: ^A� References: w aariawn 'I `V b to 25 t eina�e sne a�rvn7��es sva�eaiane cal brnia v Flas eio5 cee� w qp N R ualan'. Lembe�l GONAD 1993 oM 25an WC Oblepo Counry� 0 o.zs as �kw s. uses SAN LOS OBISPO VALLEY BASIN GSP ,. Figure 9-3 SWP with In -Lieu Agricultural Pumping Reduction -1,000 AFY— Project Scenario 1 15 Projects and Management Actions (§ 354.44) Explanation Q Representative Well — Project Pipeline ,.; — Coastal Branch Alignment Q San Luis Obispo Valley Basin Major Road Watercourse 211 Waterbody 225 200 p° 175 150 3 125 100 E V-10 SWP with In -Lieu Agricultural Pumping Reduction - 1,000 AFY — Project Scenario 1 Figure 9-3 Page 438 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.2 City of SLO Recycled Water for Agricultural Irrigation The City owns and operates a Water Resource Recovery Facility (WRRF) that treats municipal wastewater from the City, California Polytechnic State University, San Luis Obispo (Cal Poly), and the San Luis Obispo County Airport. Tertiary treated and disinfected effluent is either distributed for landscape irrigation and construction uses, or/and dechlorinated and discharged to San Luis Obispo Creek. The WRRF is required to maintain a minimum daily average year-round discharge of 2.5 cubic feet per second (cfs) of treated effluent to San Luis Obispo Creek, which equals approximately 1.6 MGD or 1,800 AFY, for protection of downstream biological resources as required by the National Oceanic Atmospheric Association, National Marine Fisheries Service (NOAA NMFS). The City of San Luis Obispo has been utilizing recycled water as a component of its multi -source water supply since 2006. The City's goal is to use this water source to the highest and most beneficial use. The City is committed to the expansion of its non -potable recycled water programs and to the development of a potable reuse program to supplement groundwater and/or surface water supplies. The delivery of the City's recycled water to parties within the Edna Valley area has been identified as a potential short-term augmentation project to offset further lowering of groundwater levels within the Edna Valley. With current in -City recycled water demands and influent, it is anticipated that the City could provide 500- 800 acre-feet of recycled water annually with quantities decreasing as new in -City users come online, indoor water conservation is increased as a result of statewide water efficiency mandates, and as the City develops potable reuse projects to supplement its water supplies. In -City groundwater basin augmentation efforts, new regulations, drought, additional in -City customers, and the like could reduce the quantity available to outside users by several hundred acre-feet per year in the foreseeable future. The project includes the construction of 2,600 feet of 8-inch pipeline, a pumpstation, and a turnout to connect to the existing Edna Valley Growers Mutual Water Company distribution system. The project would allow for approximately 100 AF in the winter months with minimal amounts available during summer months, and will replace some of the irrigation demands currently met by groundwater. 9.4.2.1 Project Benefits (§ 354.44.5) This project is considered to be one of the various projects that may provide portions of the water supply needed to reduce Edna Valley agricultural pumping by 1,000 AFY. As such, it is considered conceptually to be part of the same model scenario (i.e., Project Scenario 1) as described in Section 9.4.1 State Project Water to Agriculture Irrigation. Because of the uncertainty of the supply, no model runs were dedicated specifically to this project. It is one of the sources that would provide benefits to Basin water levels as described in Section 9.4.1.1. 9.4.2.2 Supply Reliability (§ 354.44.6) The quantity of recycled water available for use to City customers is dependent on the quantity of untreated wastewater flowing into the City's WRRF. Unlike most cities that experience relatively uniform recycled water availability throughout the year, the City of San Luis Obispo's recycled water availability is drastically impacted by the students from Cal Poly vacating the community during the summer months and thus decreasing the wastewater influent into the WRRF. This decrease in wastewater influent occurs during the summer months when the City's 50+ recycled water accounts increase irrigation to combat the warm, dry conditions. This decrease in availability, coupled with a substantial increase in demand, abnormally limits the recycled water available during the summer months. Page 439 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO Long -Term Versus Short -Term Availability While there is currently surplus recycled water available year-round, with over 150 acre-feet per month available in some winter and spring months, it is anticipated that the City will not have a significant volume of recycled water supply available to sell to any outside users from June -October once the internal City demands increase to support new residential and commercial developments. Recycled water demands from Avila Ranch, San Luis Ranch, Righetti Ranch, and other future in -City developments are expected to result in increased recycled water demand of roughly 400-500 acre-feet per year with most of this demand occurring during the summer. These developments are currently being constructed with many of the Orcutt Area developments already receiving recycled water deliveries. The City continues to update its recycled delivery projections as any amounts obligated for delivery beyond availability would need to be made up by use of City potable water supplies. This concern will continue to increase as both in -City and Cal Poly users continue to improve in their indoor water use efficiency. As the City continues to develop its groundwater pumping program, it has been identified that there is significant recharge potential (upwards of 400 acre-feet per year) within the City's portion of the SLO Valley Groundwater Basin adjacent to the WRRF. Recharge projects in other areas of the City have not yet been studied but are anticipated to increase the amount of water that could be recharged within the Basin. As the City resumes its groundwater pumping, additional capacity will likely be created within the Basin, increasing the City's need for recycled water for recharge projects that may ultimately be used for a potable reuse project. As surface water supplies are adversely impacted by climate change, augmentation of the Basin will be the City's major water supply expansion strategy and will limit water availability for outside -City interests as augmentation projects come online. Potable reuse through storage in the Basin may also address the issues with seasonal availability by creating a prolonged time lag between highly treated wastewater injection/percolation and its withdrawal for use. Physical Delivery Constraints The City's recycled water storage and distribution system was designed to provide intermittent in -City deliveries within the southern half of the City. The City's storage tank, pumps, telemetry, and pipelines were not designed to provide recycled water to outside -City customers and may require upgrades in order to accommodate continuous 24/7 delivery. Additionally, the two potential pipeline alignments that could be utilized to deliver water to the Edna Valley area are undersized and limit the ability to deliver recycled water during the winter and spring months when it is most abundantly available. One pipeline located along Broad Street near the Airport is 6-inch diameter C900 pipe. The other, located along Tank Farm Road, is 8-inch diameter ductile iron pipe. It is estimated that the larger of the two pipelines could deliver approximately 100 acre-feet of recycled water per month if operated 24-hours per day for a full month. This undersized pipelines constrain the amount of water that could be delivered to outside City customers during the winter and spring months when it is available in its highest quantities. 9.4.2.3 Project Costs (§ 354.44.8) The estimated capital cost to connect the City's recycled water distribution to the existing Edna Valley Growers Mutual Water Company distribution system is approximately $1,004,000 equating to an annual payment of $153,000 and a unit cost of $260/AF. These costs do not include the cost of the water that will be purchased from the City. The City's recycled water is approved to be sold within City limits for approximately $4,000/AF. 9.4.2.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the Basin overdraft conditions in the Edna Valley. The City and representatives from the Edna Valley have been discussing the feasibility of the project during the development of this GSP. It is estimated that the design and construction of the pipeline could occur within 1 to 3 years of the GSP Implementation. 17 Page 440 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.2.5 Basin Uncertainty (§ 354.44.9d) The addition of recycled water as a supplemental water supply source would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the project in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies the uncertainties and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.2.6 Legal Authority (§ 354.44.71 California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. The GSAs have the legal authority to conduct a feasibility study into the use of SWP as a supplemental water supply for the SLO Basin. Following the recommendation from the feasibility study the project could be implemented by the GSAs, GSC members or other parties. The City owns its recycled water and has the legal authority to sell its recycled water. 9.4.2.7 Permitting and Regulatory Processes (§ 354.44.3) This project would require review and approval by the SLO City Council. The project may require a CEQA environmental review process and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. Delivery of recycled water to the Edna Valley may require analysis to confirm that the large-scale, ongoing application of recycled water does not result in recycled water recharging the groundwater basin and thus constituting a potable reuse project. Direct application of recycled water at agronomic rates is allowable under the City's existing recycled water delivery permit. While the City has policy language that allows for the sale of recycled water outside of City limits. Specific findings must be made for this to be permitted. Examples of these findings include requirements for receiving properties to record a conservation, open space, Williamson Act, or other easement instrument to maintain the area being served in agriculture and open space, assurance that recycled water will not be used to increase development potential of the property being served, and that recycled water will not be further treated to make it potable. Contract negotiations related to the sale price of recycled water, term of delivery, etc. would require approval of the San Luis Obispo City Council. 9.4.2.8 Public Notice and Outreach (§ 354.44B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 9.4.3 State Water Project Recharge Basin To enhance recharge in the Edna Valley, a groundwater recharge basin could be constructed to percolate SWP water. A groundwater recharge basin is a bermed basin structure designed for the purpose of efficiently allowing water collected in the basin to infiltrate through the ground surface, percolate through the vadose zone, and ultimately recharge the underlying aquifer. The concept of this project is to construct a recharge basin in the Edna Valley and supply it with water obtained from the SWP to recharge the aquifer. F& Page 441 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO The conceptual location selected for this project is near the southeast corner of Biddle Ranch Road and State Highway 227 (aka, Edna Road, Figure 9-4). This area is classified as having high recharge potential in the Stillwater Percolation zone Study discussed in Chapter 4. This land is currently utilized for agriculture, and it is assumed that a parcel of land adequate to build the recharge basin could be purchased. Water would be conveyed via a 6,000 foot 6-inch pipeline from the SWP pipeline, along Biddle Ranch Rd, to a newly constructed recharge basin on approximately 5 acres of land along Orcutt Road. 9.4.3.1 Project Benefits (§ 354.44.5) In order to assess this project's benefits to the aquifer and effect on sustainability of the Basin in terms of expected water levels, Project Scenario 2 was simulated using the integrated GSFLOW model developed as part of the GSP effort. The project was defined to represent 500 AFY of supplemental water provided from the SWP made available to a newly constructed recharge basin to be located in Edna Valley. Benefits of recharge basins versus direct delivery to offset pumping include the potential to deliver water during seasonal periods when there is less demand for SWP water supplies and capacity in the SWP conveyance systems. A baseline simulation was performed as previously described. The recharge basin is assumed to be less than 500 feet by 500 feet in area, and is simulated in a single cell in the model. Recharge is input as a flux in MODFLOW (feet/day), so a flux rate equivalent to 500 AFY percolating into a 500 ft by 500 ft cell was input into model cell on a constant basis. The project was defined as beginning in 2026, allowing five years for project design and implementation. Figure 9-4 displays the baseline and Project Scenario 2 hydrographs for this project for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator. This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 2 feet at EV-16 to 52 feet at EV-04, which is the closest RMS to the recharge basin location. The water level increase in the SWP recharge basin scenario over baseline was 21 feet at EV-09, and 4 feet at EV-13 9.4.3.2 Supply Reliability (§ 354.44.6) The supply reliability of the SWP is discussed in detail in Section 9.4.1.2 and is applicable to this project. This project assumes a total of 500 AFY would be purchased and recharged in the Edna Valley. If both the SWP for Agricultural Irrigation and the SWP Recharge Basin projects were to be implemented the total capacity of SWP would be 1,500 AFY and contracts would need to be negotiated accordingly. 9.4.3.3 Project Costs (§ 354.44.8) The estimated capital cost to construct a turnout off from the Coastal Branch Pipeline and infrastructure to connect to a newly constructed recharge basin is approximately $3,624,000 which equates to annual payment of $337,000 and a unit cost of $670/AF. If multiple SWP groundwater recharge projects are implemented, the cost of the turnout and other infrastructure can be shared. These costs do not include the cost to purchase SWP or the work required to negotiate a contract with the District or District subcontractors. 9.4.3.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the Edna Valley. The feasibility study evaluation of the use of the SWP as a supplemental water source to recharge groundwater within the Edna Valley could occur within the first year of implementation. Following the recommendations of the feasibility study, negotiations to acquire SWP from the identified sellers could take up to 5 years. The design and construction of the turnout and pipeline could occur concurrent with the negotiations and be completed within 5 years. 19 Page 442 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.3.5 Basin Uncertainty (§ 354.44.9d) The addition of SWP as a supplemental water supply source would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water, and privileges. The GSAs have the legal authority to conduct a feasibility study into the recharge of SWP as a supplemental water supply for the SLO Basin. Following the recommendation from the feasibility study the project could be implemented by the GSAs, GSC members or other parties. 20 Page 443 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO - rv-6n 275 250 zz5 zoo 175 ls6 125 EV-09 225 I 200 E 175 s MO 156 -- w 1 s 1zs � 160 Eo °P3 MT y0 75 Prepared for: N References: o.r e�i<iwn o 1zs zs 1_cmaio �sTe enrvno lees —ia.e cai b���avnas w.os �e� Mies 23an Ww Oblspo0ouniy� 0 0.25 0.5 1Kj� 3. U5�5 SAN UAS OBISPO VALLEY BASIN GSA n Figure 9-4. SWP Recharge Basin — 500 AFY — Project Scenario 2 256 zzs 200 v = 275 150 125 100 21 Projects and Management Actions (§ 354.44) Explanation Representative Well Ak SWP Turnout — Project Pipeline — Coastal Branch Alignment Proposed Recharge Basin E3 San Luis Obispo Valley Basin Major Road Watercourse Waterbody SWP Recharge Basin — 500 AFY — Project Scenario 2 Figure 9-4 Page 444 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.3.7 Permitting and Regulatory Processes (§ 354.44.3) No permits or regulatory processes would be necessary for development of the feasibility study. However, implementation of this project will likely require a CEQA environmental review process and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. A new connection or turnout infrastructure requires coordination and agreements with the District, CCWA, and DWR. 9.4.3.8 Public Notice and Outreach (§ 354.44B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 9.4.4 State Water Project to Golden State Water Company Golden State Water Company (GSWC) currently provides water to a small service area of County administered land in the central part of the Basin, near the boundary of Edna Valley and San Luis Valley. GSWC obtains its supply from groundwater wells within their service area. The recent drought resulted in significant constraints on GSWC's groundwater supplies. Because their service area is relatively small, their ability to site new wells to expand their source locations is limited. For this reason, the conceptual project of obtaining SWP water to augment GSWC's current supplies is evaluated. This project assumes a SWP delivery of 200 AFY to GSWC, representing about 50% of it's long term demand. To implement this project, a turnout to the SWP pipeline along Orcutt Road will be required. From the corner of Orcutt Road and Biddle Ranch Road, approximately 8,000 feet of pipeline along Biddle Ranch Road will be required to convey the water from the SWP pipeline to the edge of the GSWC service area. Infrastructure improvements internal to GSWC's system are not included in this project evaluation. 9.4.4.1 Project Benefits (§ 354.44.5) In order to assess this project's benefits to the aquifer and effect on sustainability of the Basin in terms of expected water levels, Project Scenario 3 was simulated using the integrated GSFLOW model developed as part of the GSP effort. This project assumes a 200 AFY reduction in pumping by GSWC. Edna Ranch MWC and Varian Ranch MWC pumping was also reduced, but these water companies are distant enough that results from one are not expected to have a significant impact on the other. As with the scenarios for agricultural pumping reduction, the water to offset this pumping reduction may come from this project or another source; in this case, additional water for GSWC may come from the SWP or/and City of SLO water (Section 9.4.5). Modeled pumping for GSWC was reduced by 50% from recent annual pumping volumes at their operating wells. It is assumed that the remaining demand for GSWC's service area would be met through supplemental water from the SWP. Figure 9-5 displays the baseline and project scenario hydrographs for this project for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator (EV-04, EV- 09, EV-13, and EV-16). This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 3 feet at EV-13 to 15 feet at EV-09, which is a GSWC well. 22 Page 445 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.4.2 Supply Reliability (§ 354.44.6) The supply reliability of the SWP is discussed in detail in Section 9.4.1.2 and is applicable to this project. This project assumes a total of 200 AFY would be purchased and delivered to GSWC. 9.4.4.3 Project Costs (§ 354.44.8) The estimated capital cost to construct a turnout off from the Coastal Branch Pipeline, infrastructure to connect to the GSWC is approximately $2,685,000 which equates to annual payment of $192,000 and a unit cost of $960/AF. If multiple projects which require SWP water are implemented, the cost of the turnout and other infrastructure can be shared. These costs do not include the cost to purchase SWP or the work required to negotiate a contract with the District or District subcontractors. 9.4.4.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the Edna Valley The feasibility study into the use of the SWP as a supplemental water source to GSWC would occur within the first year of implementation. Following the recommendations of the feasibility study, negotiations to acquire SWP from the identified sellers could take up to 5 years. The design and construction of the turnout and pipeline could occur concurrent with the negotiations and occur within 5 years. 9.4.4.5 Basin Uncertainty (§ 354.44.9d) The addition of SWP as a supplemental water supply source to GSWC would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. The GSAs have the legal authority to conduct a feasibility study into the obtaining SWP as a supplemental water supply for the SLO Basin. Following the recommendation from the feasibility study the project could be implemented by the GSAs, GSC members or other parties. 9.4.4.7 Permitting and Regulatory Processes (§ 354.44.3) No permits or regulatory processes would be necessary for development of the feasibility study. However, implementation of this project will likely require a CEQA environmental review process and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. A new connection or turnout infrastructure requires coordination and agreements with the District, CCWA, and DWR. 9.4.4.8 Public Notice and Outreach (§ 354.44B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 23 Page 446 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO - Ev-on mo zz5 w zoo x v 175 W I50 n 125 77, pp EV-09 225 I 200 175 rno 150 -- 0 3 100 � MT 75 I. EVJ74�B1o0" a e° E V-11 Q QC n Projects and Management Actions (§ 354.44) Explanation Representative Well Ak SWP Turnout — Project Pipeline — Coastal Branch Alignment San Luis Obispo Valley Basin Major Road Watercourse Waterbody EV-16 250 � 225 200 175 P 150 Y \ 125 100 \ EY-16 y V7, A%, il- O A � Prepared for: N Rererencea: SWP Purveyor In -Lieu Pumping Reduction — wy��p o 25 A°�f;mmP;°c^m°'aicoaP1oeC1r°`°aV`"5°OSFet GSWC=200AFY, VRMWCBERMWC=50AFY — '= zs w"moexoco it Project Scenario 3 0 0.25 0.5 1Kj� 3. UGGG SAN UAS OBISPO VALLEY BASIN GSA Figure 9-5 Figure 9-5 SWP Purveyor In -Lieu Pumping Reduction — GSWC = 200 AFY, VRMWC & ERMWC = 50 AFY — Project Scenario 3 24 Page 447 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.5 City of SLO Potable Water to Golden State Water Company The concept of this project is that GSWC would purchase treated drinking water from the City of SLO on an interruptible basis to augment their current supply from wells within their service area. This project would require construction of approximately 4,850 feet of 6-inch pipeline and a pump station to connect the City's existing potable water pipelines along Buckley Road to GSWC's service area. The City of San Luis Obispo has longstanding policy that only allows for non -potable and recycled water to be sold outside of City limits. Policy does not exist to support the sale of potable water outside of City limits. Analysis of this project is included in the GSP so that some basic analysis of cost and feasibility is documented in the event that there was a change in the City's policy regarding the sale of potable water supplies. 9.4.5.1 Project Benefits (§ 354.44.5) This project is considered to be one of the various projects that may provide supply to reduce pumping by the water purveyors in Edna Valley. As such it is considered conceptually similar to the same model scenario as described in 9.4.4, State Project Water to GSWC. Modeled pumping for GSWC was reduced by 50% from recent annual pumping volumes at their operating wells. It is assumed that the remaining demand for GSWC's service area would to be met through supplemental water from the City of SLO. Figure 9-5 displays the baseline and project scenario hydrographs for this project for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator (EV-04, EV- 09, EV-13, and EV-16). This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 3 feet at EV-13 to 15 feet at EV-09, which is a GSWC well. The water level increase over baseline was 4 feet at EV-04, and 7 feet at EV-16 (a MWC well). 9.4.5.2 Supply Reliability (§ 354.44.6) The City of San Luis Obispo's potable water supplies have proven to be reliable in meeting the City's water needs and are projected to safely meet the City's General Plan buildout needs. Analysis of the ability for the City's supplies to continually deliver up to 200 AFY to GSWC, have not been examined and cannot be confirmed. 9.4.5.3 Project Costs (§ 354.44.8) The estimated capital cost to construct a connection from the City of SLO to GSWC is approximately $1,739,000 which equates to annual payment of $127,000 and a unit cost of $640/AF. Because existing policy does not allow for the sale of potable water outside of City limits, the City does not have standard rates adopted for sales to new outside -City customers. However, the City does have a few outside -City accounts that are served water as part of long-standing agreements dating back to the early 1900s. These properties pay twice the City's in -City water rates for potable water, which equal approximately $8,200/AF. The delivery of potable water to GSWC could require upgrades to City's water distribution system (pipelines, storage tanks, pump stations, etc.) in order to safely and effectively deliver potable water to GSWC's service area. Costs for all required infrastructure upgrades would be paid in full by GSWC and are not included in the construction costs referenced above. Additionally, connection to the City's potable water system may require the payment of capacity and connection fees, also commonly known as impact fees, depending on the details of the water sales agreement. These fees have not been included in the construction costs referenced above. 9.4.5.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the Edna Valley specifically in and around the GSWC service area. As the City's current policies effectively prohibit the sale 25 Page 448 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO of potable water outside of City limits, a timeline for the policy changes required for the sale of potable water supplies is unknown. Distribution system infrastructure upgrades that could be triggered by the sale of potable water outside of City limits could take 5 years or longer to construct, depending on the magnitude of required improvements. 9.4.5.5 Basin Uncertainty (§ 354.44.9d) The addition of the City of SLO potable water as a supplemental water supply source to GSWC would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.5.6 Legal Authority (§ 354.44.7) California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. The GSAs have the legal authority to conduct a feasibility study into the delivering the City of SLO potable water as a supplemental water supply for the Edna Valley portion of the SLO Basin. 9.4.5.7 Permitting and Regulatory Processes (§ 354.44.3) This project may require a CEQA environmental review process, and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. This project would require amendments to the City's General Plan to allow for the sale of potable water outside of City limits, even on a short term or interruptible basis, and would require Local Agency Formation Commission (LAFCO) review and approval. 9.4.5.8 Public Notice and Outreach (§ 354.44B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 9.4.6 Varian Ranch Mutual Water Company Arroyo Grande Subbasin Wells The Varian Ranch MWC (VRMWC) is located in the southeastern extent of the Basin and currently supplies its service area from wells within the Basin. However, its service area extends into the neighboring Arroyo Grande Subbasin of the Santa Maria River Valley Groundwater Basin (SMRVGB). Twenty-two of their fifty- one parcels are located outside of the Basin in the adjacent Arroyo Grande Creek watershed. VRMWC owns an existing well, located on its property in the Arroyo Grande Subbasin that has been tested and found to be suitable for use as a domestic supply source for its service area. The concept of this project is to build a conveyance pipeline to deliver approximately 50 AFY of water from the well that VRMWC owns in the Arroyo Grande Subbasin to an interconnection point within its current distribution system in the Basin. The project would also evaluate a connection with the adjacent Edna Ranch MWC (ERMWC). It is estimated that this pipeline will be 6 inches in diameter and approximately 10,850 feet long. The project also includes well pump and well site improvements. Utilization of this well to supply a portion of VRMWC and ERMWC's demand would reduce the pumping required of their wells in the Basin, and would benefit water levels in the area. Page 449 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.6.1 Project Benefits (§ 354.44.5) This project is considered to be one of the various projects that may provide supply to reduce pumping by the small water purveyors in Edna Valley. As such it is considered conceptually to be part of the same scenario as described in Section 9.4.4, SWP to GSWC. Because of the uncertainty of the supply, no model runs were dedicated specifically to this project. Modeled pumping for both ERMWC and VRMWC wells in the Edna Valley were reduced by 50 AFY and is offset by groundwater pumped from the Arroyo Grande Subbasin. Figure 9-5 displays the baseline and project scenario hydrographs for this project for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator (EV-04, EV- 09, EV-13, and EV-16). This figure indicates that the increase in water levels over the baseline scenario in year 2042 is about 7 feet at EV-16 (a MWC well). 9.4.6.2 Supply Reliability (§ 354.44.6) The water source for this project is groundwater from the Arroyo Grande Subbasin. The County and City of Arroyo Grande are currently developing a GSP for the Arroyo Grande Subbasin and will be developing a detailed water budget which will provide information regarding the reliability of the groundwater source. 9.4.6.3 Project Costs (§ 354.44.8) The estimated capital cost to convey groundwater from the Arroyo Grande Subbasin to the Varian Ranch distribution system is approximately $2,701,000 equating to an annual payment of $176,000 and a unit cost of $4,200/AF. These costs do not include any costs to purchase the water since the VRMWC currently owns the well. 9.4.6.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the southeastern portion of Edna Valley. The feasibility study into the use of VRWMC wells in Arroyo Grande Subbasin as a supplemental water source to both VRMWC and ERMWC would occur within the first year of implementation. Following the recommendations of the feasibility study the design and construction of the turnout and pipeline could occur concurrent with the negotiations and occur within 3 years. 9.4.6.5 Basin Uncertainty (§ 354.44.9d) The addition of the Arroyo Grande Varian Ranch MWC wells as a supplemental water supply source to VRMWC and Edna Ranch MWC would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.6.6 Legal Authority (§ 354.44.7) California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. The GSAs have the legal authority to conduct a feasibility study into the utilizing the Arroyo Grande Subbasin as a supplemental water supply for the southeastern portion of Edna Valley. San Luis Obispo County Code Chapter 8.95 currently requires that a permit be obtained for any export of groundwater greater than 0.5 AFY from a Bulletin 118 defined groundwater basin within the County. The ordinance requires that the export permit only be approved if the Director of Public Works finds that the 27 Page 450 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO proposed export will not cause or contribute to significant detrimental impacts to groundwater resources, including such impacts to health, safety and welfare of overlying property owners. 9.4.6.7 Permitting and Regulatory Processes (§ 354.44.3) This project may require a CEQA environmental review process, and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. 9.4.6.8 Public Notice and Outreach (§ 354.44B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 9.4.7 State Water Project to the Mutual Water Companies The VRMWC and ERMWC located in the southeastern extent of the Basin, currently provides water supply to their service areas from wells within the Basin. The recent drought resulted in significant constraints on their supplies. To implement this project, a turnout to the SWP pipeline along Orcutt Road will be required. From the corner of Orcutt Road and Biddle Ranch Road, approximately 8,000 feet of pipeline along Biddle Ranch Road will be required to convey the water from the SWP pipeline to the edge of the ERMWC service area. Infrastructure internal to ERMWC and VRMWC's system is not included in this project evaluation. 9.4.7.1 Project Benefits (§ 354.44.5) This project is considered to be one of the various projects that may provide water supply to reduce pumping by the water purveyors in Edna Valley. As such it is considered conceptually to be part of the same scenario as described in 9.4.4, SWP to GSWC. Because of the uncertainty of the supply, no model runs were dedicated specifically to this project. It is one of the sources that would provide the benefits to Basin water levels described in Section 9.4.4. 9.4.7.2 Supply Reliability (§ 354.44.6) The supply reliability of the SWP is discussed in detail in Section 9.4.1.2 and is applicable to this project. This project assumes a total of 50 AFY would be purchased and served to ERMWC and VRMWC. 9.4.7.3 Project Costs (§ 354.44.8) The estimated capital cost to construct a turnout off from the Coastal Branch Pipeline, infrastructure to connect to the ERMWC and VRMWC is approximately $835,000 which equates to annual payment of $59,000 and a unit cost of $1,180/AF. If multiple projects which require SWP water are implemented, the cost of the turnout and other infrastructure can be shared. These costs do not include the cost to purchase SWP or the work required to negotiate a contract with the District or District subcontractors. 9.4.7.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the Edna Valley The feasibility study into the use of the SWP as a supplemental water source to ERMWC and VRMWC would occur within the first year of implementation. Following the recommendations of the feasibility study, negotiations to acquire SWP from the identified sellers could take up to 5 years. The design and construction of the turnout and pipeline could occur concurrent with the negotiations and occur within 5 years. W. Page 451 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.7.5 Basin Uncertainty (§ 354.44.9d) The addition of SWP as a supplemental water supply source to ERMWC and VRMWC would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.7.6 Legal Authority (§ 354.44.7) California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. The GSAs have the legal authority to conduct a feasibility study into the obtaining SWP as a supplemental water supply for the SLO Basin. Following the recommendation from the feasibility study the project could be implemented by the GSAs, GSC members or other parties. 9.4.7.7 Permitting and Regulatory Processes (§ 354.44.3) No permits or regulatory processes would be necessary for development of the feasibility study. However, implementation of this project will likely require a CEQA environmental review process and may require an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. A new connection or turnout infrastructure requires coordination and agreements with the District, CCWA, and DWR. 9.4.7.8 Public Notice and Outreach (§ 354.44.B) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 9.4.8 Price Canyon Discharge Relocation Sentinel Peak Resources LLC (Sentinel Peak) is an energy company that operates a well field that extracts petroleum hydrocarbons from an area approximately 1-2 miles southwest of Edna Valley in Price Canyon. Sentinel Peak owns and operates a water reclamation facility that treats water to (CSLRCD, 2014) tertiary standards and has an NPDES permit to discharge into Pismo Creek about 1 mile southwest of Highway 227 near Price Canyon Road. The discharge permit is primarily provided for increased flow in Pismo Creek and wildlife propagation with a secondary benefit to agriculture. The proposed project would change the current point of discharge by about 3.5 miles to the upper portion of West Corral de Piedras Creek in the Edna Valley. The new discharge point would be approximately 1 mile east of Orcutt Road. The project would provide increased benefit to fisheries from increased streamflow, and also benefit Edna Valley agriculture by increasing streamflow percolation to the underlying aquifers. For the purpose of this analysis, it is assumed that 500 AFY of water will be available to deliver to the new discharge location, resulting in approximately 350 acre-feet of recharge to the Basin. It is anticipated that a 6-inch diameter 17,760 foot long PVC pipeline would convey the water to the new discharge point. A booster pump would move the water through this pipeline to the new discharge location. The pipeline would cross approximately 6 agricultural properties, whose owners have already expressed their willingness to participate in the project, 4 creek crossings and 1 railroad crossing. 29 Page 452 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.8.1 Project Benefits (§ 354.44.5) In order to assess this project's benefits to the aquifer and effects on the sustainability of the Basin, Project Scenario 4 was simulated using the integrated GSFLOW model developed as part of the GSP efforts. This project assumes a transfer of the 500 AFY of tertiary treated water that is currently discharged from Sentinel Peak's treatment plant to Pismo Creek downstream of the Basin to a new discharge point on West Corral de Piedra Creek near the northern edge of the Basin. Therefore, 500 AFY (0.7 cubic feet per second) was added as inflow to the MODFLOW Stream Flow Routing package in the first model cell representing West Corral de Piedras Creek that is in the Basin. It should be noted that adding this inflow to the stream segment is not equivalent to adding recharge directly to the aquifer. The additional streamflow from the project discharge will be routed downstream in the model, and will ultimately result in an increased amount of streamflow percolation to the aquifer. However, this amount of additional streamflow percolation, which would be additional recharge to the aquifer that will benefit the groundwater users in the Basin, is not directly defined by the model user. It is calculated by the model based on the parameters defined in the SFR package. Evaluation of the model water budget results from the baseline and project scenarios indicates that an average of approximately 350 AFY of the 500 AFY project stream inflow associated with this project ultimately percolates to the aquifer to increase storage in the Basin. Figure 9-6 displays the baseline and project scenario hydrographs for this project for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator (EV-04, EV- 09, EV-13, and EV-16). This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 6 feet at EV-16 and EV-13, to 8 feet at EV-04 and EV-09. Inspection of comparative water levels along West Corral de Piedras Creek indicate a water level increase of over 30 vertical feet along the creek itself. 9.4.8.2 Supply Reliability (§ 354.44.6) The supply reliability of the Price Canyon discharge is tied to the operations related to the extraction of petroleum hydrocarbons from the Price Canyon and the associated permits. The long-term availability of this water source is uncertain. 9.4.8.3 Project Costs (§ 354.44.8) The estimated capital cost to relocate the discharge point approximately 3.5 miles to West Corral de Piedras Creek is $4,909,000 equating to an annual payment of $375,000 and a unit cost of $750/AF. These costs do not include the cost of the water that will be purchased from Sentinel Peak. 9.4.8.4 Project Implementation (§ 354.44.4) The circumstance for implementation of this project is driven by the overdraft conditions in the Edna Valley A mitigated negative declaration/initial study was performed in July 2014 by the Coastal San Luis Resource Conservation District as the lead agency. The feasibility study into the relocation of the Price Canyon discharge point would occur within the first year of implementation. Negotiations between Sentinel Peak and representatives from the Edna Valley Growers MWC have been ongoing throughout the development of this GSP. The design and construction of the turnout and pipeline could occur concurrent with the negotiations and occur within 3 years. 9.4.8.5 Basin Uncertainty (§ 354.44.9d) The increased recharge to the Edna Valley as the result of the relocation of the Price Canyon discharge point would help address the uncertainty of the estimated overdraft described in Chapter 6 - Water Budget in the Edna Valley portion of the Basin. The benefits from the projects in terms of improved water levels in the Basin are evaluated using the integrated GSFLOW model. It should be understood that there is uncertainty that is inherent in the modeling process, including uncertainty with respect to parameters describing the subsurface environment, historical volumes of pumping, etc. The Integrated Model 30 Page 453 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO Calibration TM (Appendix E) identifies uncertainty and the need for additional data collection in the conceptual model, model parameters, and calibration. 9.4.8.6 Legal Authority (§ 354.44.7) California Water Code §10726.2 provides GSAs the authority to purchase, among other things, land, water rights, and privileges. 9.4.8.7 Permitting and Regulatory Processes (§ 354.44.3) This project may require a CEQA environmental review process and an Environmental Impact Report or a Mitigated Negative Declaration (the review could also result in a Negative Declaration or Notice of Exemption). Additionally, permits from a variety of state and federal agencies may be necessary, and any project that coordinates with federal facilities or agencies may require NEPA documentation. In addition, permits from the following government organizations that may be required to relocate the Price Canyon Discharge Point include: ■ United States Army Corps of Engineers (USACE) —A Regional General Permit may be required if there are impacts to wetlands or connections to waters of the United States. ■ California Department of Fish and Wildlife (CDFW) — A Standard Agreement is required if the project could impact a species of concern. ■ Environmental Protection Agency (EPA) Region 9 — National Environmental Policy Act (NEPA) documentation must be submitted for any project that coordinates with federal facilities or agencies. Additional permits may be required if there is an outlet or connection to waters of the United States. ■ National Marine Fisheries Service (NMFS) —A project may require authorization for incidental take, or another protected resources permit or authorization from NMFS. ■ California Department of Transportation (Caltrans) —An Encroachment Permit is required if any state highway will be obstructed 9.4.8.8 Public Notice and Outreach (§ 354.44.13) The public notice and outreach associated with this project would occur through GSA, GSC and/or future governance structure public meetings. If CEQA is required, the project will follow the public noticing requirements required by CEQA. 31 Page 454 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO ns o zz5 w zoo d s vs 3 — MT sso ns._.a n 125 g EV-09 zzs m n T zoo — 175 d 150 _ Mo z 3 I. Vt lao S 75 "s Prepared for: ^�r� Referenws: wr arramn 'I `V b is 25 t e'nale ss mm ^rvn�,aes sva�eaiane cal brnia v rlas cio5 r e� w qp N Rulan Lembe�r GonkrmelGonlc oM� 25an Ww Oblepo Counry� 0 o.zs as ,�� s. uses SAN UAS OBISPO VALLEY BASIN GSA Figure 9-6. Relocation of Price Canyon Discharge Point — 500 AFY EV-13 zsa zzs � m m. zaa 175 MT u 150 3 225 IN Projects and Management Actions (§ 354.44) Explanation Q Representative Well 6d Discharge Point — Project Pipeline r — Coastal Branch Q San Luis Obispo Valley Basin b Major Road Watercourse ti Waterbody � v 225 200 \ 175 ISO EV-13 ?r9 v O � - 125 \ 1W 32 EVA6 Relocation of Price Canyon Discharge Point — 500 AFY Figure 9-8 Page 455 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.4.9 Modeling of Multiple Projects Basin groundwater modeling results for each of the projects previously discussed has represented the project described exclusively, and does not model other projects concurrently. The model results indicate that it is unlikely that any single project presented will, by itself, maintain water levels above the defined MTs at the RMSs. Therefore, an additional model scenario was developed in which multiple projects were represented simultaneously, to demonstrate potential results of a multi -project approach. Technical details of each of the individual projects are presented in the original chapter sections and are not represented here. The projects that are modeled in this multiple -projects scenario are: • Reduction of agricultural pumping by 1,000 AFY (Sections 9.4.1, 9.4.2) • Reduction of Edna Valley water purveyor pumping by 250 AFY (Sections 9.4.4, 9.4.5, 9.4.6, 9.4.7) • State Water Project Recharge Basin — 500 AFY (Section 9.4.3) • Relocation of Sentinel Peak WRF discharge—350AFY (Section 9.4.8) As with the individual modeled project scenarios, all projects are represented as beginning in the year 2026. Figure 9-7 displays the baseline and Project Scenario 5 hydrographs for the combined projects for the four Edna Valley wells identified as RMS for the Chronic Lowering of Groundwater Levels Sustainability Indicator (EV-04, EV-09, EV-13, and EV-16). This figure indicates that the increase in water levels over the baseline scenario in year 2042 at these wells ranges from 39 feet at EV-16 to 63 feet at EV-EV-09. The projected water level increase over baseline was 46 feet at EV-16, and 62 feet at EV-04. This scenario indicates that with all the projects presented incorporated into the management of the Basin, the benefit to water levels is more than required to achieve sustainability. So just as it has been stated previously that no one single project will likely bring the basin into sustainability, this scenario indicates that all of the projects presented are not required to achieve this goal. 33 Page 456 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 275 250 MOB 225 w zoo 175 MT I50 �i' 125 e r• o v� a w S EV-09 225 200 175 = 150 ia 1m 3 100 75 8 250 225 200 m 175 EV-01 a 9 H 150 3 ��.0.RN�N.RO 225 e `ma 100 Projects and Management Actions (§ 354.44) Explanation Q+ Representative Well Project Pipeline — Coastal Branch Alignment Q San Luis Obispo Valley Basin N Major Road w Watercourse 9 '—� Waterbody a R w . ~ l h EV-16 250 225 _ 200 z c 175 2R�.G u 150 ?p 3 \ 125 100 Prepared for: N References: o.r e�i<iwn o rzs zs lcmaio �sTe enrvno lees —ia.e cal br,.avnas Mies 23an Ww OblyoOouniy� 0 o.zs as a�w s. uses SAN LOS OBISPO VALLEY BASIN GSP = Figure 9-7Model Results from the Combined Modeled Project Scenarios — Project Scenario 5 34 EV-16 Model Results from the Combined Modeled Project Scenarios — Project Scenario 5 Figure 9-7 Page 457 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.5 MANAGEMENT ACTIONS The management actions in this plan include the expansion of the monitoring network, development and implementation of a groundwater extraction metering and reporting plan, and the development of a demand management plan. 9.5.1 Expand Monitoring Network This management action expands the monitoring network from the current County monitoring network of 12 wells to the new network of 40 monitoring wells as presented in Chapter 7 within the first two years of the GSP implementation. Chapter 7 describes a proposed monitoring network that has adequate spatial resolution to properly monitor changes to groundwater and surface water conditions relative to SMCs within the Basin. The network will provide data with sufficient temporal resolution to demonstrate short- term, seasonal, and long-term trends in groundwater and related surface conditions. Included in the chapter are recommendations for additional monitoring sites to better understand the groundwater and surface water interactions which include five surface water gages which will be paired with five monitoring wells (Appendix H). 9.5.2 Groundwater Extraction Metering and Reporting Plan As described in Chapter 6 — Water Budget, groundwater extraction from wells is the primary component of outflow within the groundwater budget. Estimates for historical pumping were derived from various sources, including purveyor records, land use data and water duty factors, and daily soil -moisture budgets. The total estimated groundwater production in the SLO Basin during the water budget period of 2016 to 2019 was approximately 6,000 AFY. Of the 6,000 AFY, only about 5% or 300 AFY is metered. Groundwater purveyor meter records were provided by the City of San Luis Obispo, Golden State Water Company, Edna Ranch MWC, and Varian Ranch MWC. A groundwater extraction metering and reporting plan is a foundational component of the GSP that will facilitate the reporting of groundwater extraction data and the development of a groundwater accounting framework. The collection and reporting of this data will enable the GSAs to adaptively manage the groundwater resources. The location and quantity of agricultural pumping was identified as a significant data gap during the development of the water budget and integrated model. The collection of metered groundwater pumping data will provide a key metric to evaluate the effectiveness of the demand management strategies that will be included in the Demand Management Plan. The Groundwater Extraction Metering and Reporting Plan will include a de minimis self - certification and non de minimis extraction and reporting program. SGMA provides the authority of a GSA to meter groundwater production: 10725.8. MEASUREMENT DEVICES AND REPORTING; INAPPLICABILITY OF SECTION TO DE MINIMIS EXTRACTORS (a) A groundwater sustainability agency may require through its groundwater sustainability plan that the use of every groundwater extraction facility within the management area of the groundwater sustainability agency be measured by a water -measuring device satisfactory to the groundwater sustainability agency Under California Water Code §10725.8(e) Measurement Devices and Reporting, SGMA exempts de minimis extractors from metering requirements. 9.5.2.1 De Minimis Self -Certification De minimis extractor means a person who extracts, for domestic purposes, two acre-feet or less per year (CWC 10721). The GSAs will consider developing an approach and process to allow de minimis basin extractors to self -certify that they extract two (2) acre-feet or less per year for domestic purposes. 35 Page 458 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO § 1030 g) "Domestic purposes" has the some meaning as "domestic uses" as defined in section 660 of Division 3 of Title 23 of the California Code of Regulations for the purposes of identifying if an extractor is a de minimis extractor § 660. Domestic Uses. Domestic use means the use of water in homes, resorts, motels, organization camps, camp grounds, etc., including the incidental watering of domestic stock for family sustenance or enjoyment and the irrigation of not to exceed one-half acre in lawn, ornamental shrubbery, or gardens at any single establishments. The use of water at a camp ground or resort for human consumption, cooking or sanitary purposes is a domestic use. De-minimis groundwater extractors will not be regulated under this GSP. Growth of de minimis groundwater extractors could warrant regulated use in this GSP in the future. Growth will be monitored and reevaluated periodically. Estimated groundwater extractions from de-minimis users will be documented in the annual reports. 9.5.2.2 Non -De Minimis Extraction and Reporting Program During the first five years of implementation, the Groundwater Extraction Metering and Reporting Plan will be developed for non deminimis users to report extractions using metering devices or other suitable methods. Water Code § 10725.8 provides GSAs the power through their GSPs to measure the use of groundwater extraction facilities for non de minimis extractions. 9.5.3 Demand Management Plan A demand management plan will be developed and will include the documentation of water conservation measures taken by the purveyors, documentation of irrigation efficiencies of the agricultural fields, water efficient crop conversion, volunteer crop fallowing and pumping reductions. It is intended that the Demand Management Plan will recognize measures already taken by purveyors to increase water conservation or water use efficiency prior to the adoption of the GSP. 9.5.3.1 Water Conservation Measures The purveyors in SLO Basin have implemented significant water conservation measures during the most recent drought. The following sections summarize the water conservation measures that the metered purveyors (City of SLO, GSWC, VRMWC, ERMWC) have taken to reduce their water use and will be described in more detail in the demand management plan. 9.5.3.1.1 City of SLO The City of San Luis Obispo has had a defined water conservation program since the 1970s. As an original signatory to the California Urban Water Conservation Council, the City has not maintained effective water conservation programs for several decades. In an effort to preserve groundwater supplies, the City has made significant investments in three surface water reservoirs and a recycled water program. Today the City's per -capita water use is amongst the lowest in the state and is approximately half of what it was in the late 1980s. The City's current GPCD water demand is approximately 92 and has seen virtually no increase since the end of the 2012-2015 drought. City staff anticipate that GPCD water use within the City will continue to decrease as the State of California adopts enhanced conservation and water use efficiency mandates. 9.5.3.1.2 Mutual Water Companies Edna Ranch East and Varian Ranch MWCs have implemented water conservation measures in response to Basin conditions and the drought since 2014. The MWC's presented a technical memorandum at the December 9, 2020 GSC Meeting which documented the conservation measures taken by the MWC's and is summarized below (Wallace Group, 2020): Page 459 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO New monitoring technology, combined with conservation policies, have resulted in well water production of 35% compared to the 2013 baseline year, and 26% compared to the 10 year period of 2005 through 2014. The combined groundwater production of the MWC's (75 AFY on average over the last 5 years) and represents approximately 2% of the total production in the Edna Valley. 9.5.3.1.3 Golden State Water Company In response to the Governor's Executive Order (B-29-15) the State Water Resources Control Board (Water Board) imposed restrictions to achieve a statewide 25% reduction in potable urban water usage through February 28, 2016. These restrictions will require water consumers to reduce usage as compared to the amount they used in 2013. (GSWC, 2015). A Staged Mandatory Conservation and Ration Plan was developed and implemented in 2015. GSWC's Edna System is currently in Stage 2 which includes the following conservation measures: • Stage 1: Outdoor irrigation limited to two days per week, before 8 AM or after 7 PM; even addresses on Sunday and Wednesday, odd addresses on Tuesday and Saturday • Stage 2: Irrigation restrictions from Stage 1; $2.50 emergency surcharge per CCF over allocation GSWC has reduced the groundwater production from about 318 AFY in 2013 to approximately 210 AFY in 2019. 9.5.3.2 Irrigation Efficiency Improvements Many of the agricultural users of groundwater in the Basin have implemented efficient irrigation methods and more is envisioned by agricultural operations to improve the irrigation efficiencies. There are potential irrigation efficiency benefits to the Basin that can be realized by changing the irrigation methods for some types of crops. Irrigation efficiency refers to the ratio of the amount of water consumed by the crop to the amount of water supplied through irrigation. Some irrigation water may be lost to evaporation, to surface runoff, or to deep percolation past the plant root zone. However, some of the deep percolation water may return to the underlying aquifer as illustrated later in this section. Irrigation methods vary in how efficient they utilize water, thus leaving an opportunity for modification in irrigation methods to result in reductions in water use. For example, flood irrigation is less efficient than spray irrigation, which is less efficient than drip irrigation applied at the surface, which is less efficient than drip irrigation applied directly to the root zone. Other on -farm water conservation measures may be implemented to improve irrigation efficiencies such as irrigation water management practices and measurement of pump flows. If a large enough area of agricultural fields convert to more efficient methods of irrigation, there may be a net benefit to the Basin that could offset needs for direct pumping reductions. A key component to understanding the net benefit (gain) in water savings is the concept of irrigation return flow, i,e, the amount of water that percolates past the root zone, to ultimately reach and recharge the underlying aquifer. The following analysis demonstrates an example of this concept. Figure 9-8 uses data that are approximately representative of conditions in Edna Valley. If it is assumed that the consumptive demand of a specified area of crops is 3,520 AFY, the amount of required water and calculated irrigation return flow to the aquifer under varying assumptions of irrigation efficiency may be significantly different. Figure 9-8 presents a visual presentation of this analysis and documents how improvements to irrigation efficiency can result in recovery of groundwater levels. 37 Page 460 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 80% Irrigation Efficiency IRRIGATION PUMPING OF 4,400 AFY CROP CONSUMPTIVE USE 3,520 AFY Alllllh�" t tRETURN FLOW OF 660 AFY ALLUVIUM LOSS OF 220 AFY NET REMOVAL 3,740 AFY Projects and Management Actions (§ 354.44) 90% Irrigation Efficiency IRRIGATION PUMPING OF 3,911 AFY CROP CONSUMPTIVE USE 3,520 AFY AGRICULTUREE t ROOT ZONE RETURN FLOW OF LOSS OF 293 AFY 98 AFY SWIL ~ ALLUVIUM NET REMOVAL 3,618 AFY NET BENEFIT122 AFY FIGURE 9.8 Irrigation Efficiency Comparison San Luis Obispo, California GSI Figure 9-8 Irrigation Efficiency Comparison Under the assumption of 80% irrigation efficiency, groundwater pumping of 4,400 AFY is required to provide the crop consumptive demand of 3,520 AFY (i.e., 3520/4400 = 80%). This results in 880 AFY of pumped water that is not directly up taken by the crop. For this analysis the assumption used in water budget calculations (Chapter 6) is that 75% of the unused water reaches to the aquifer as return flow. (It is assumed the remainder is lost to evaporation or permanent entrapment in the vadose zone pore space). Therefore, 660 AFY reaches the aquifer as return flow. Thus the net removal from the aquifer in this example is 3,740 AFY (4,400 AFY pumped reduced by 660 AFY of return flow). If it is assumed that conversion to more efficient irrigation methods results in overall irrigation efficiency of 90%, groundwater pumping of 3,911 AFY is required to provide the crop consumptive demand of 3,520 AFY (i.e., 3520/3911= 90%). This results in 391 AFY of pumped water that is not directly up taken by the crop. Under the same assumptions as previously discussed, 293 AFY reaches the aquifer as return flow and 98 AFY is lost. Thus, the net removal from the aquifer in this example is 3,618 AFY (3,911 AFY pumped reduced by 293 AFY of return flow). The difference in net removal from the aquifer under the assumptions of improved irrigation efficiency, displayed on Figure 9-8, is 122 AFY. This, then, is the net benefit to the aquifer of improving irrigation efficiency from 80% to 90%. It is acknowledged that this example calculation is conceptual. Although groundwater pumping is easily measured, it is very difficult to accurately measure irrigation return flow, or the evaporative losses of applied irrigation. However, the hydrologic assumptions behind this analysis are well founded and commonly accepted in the industry. Therefore, this analysis demonstrates that conceptually there will be a net benefit to the aquifer if irrigation efficiency is improved basin wide. 122 AFY of water is approximately Page 461 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 10% of the Edna Valley overdraft calculated in Chapter 6. This indicates that overall improved irrigation efficiency can be a significant contributor to bringing the Basin into sustainability. With the implementation of the Groundwater Extraction and Metering plan, the agricultural entities that implement improved irrigation methods will be able to document the improvements with reported meter readings. 9.5.3.3 Volunteer Water Efficient Crop Conversion Chapter 6 - Water Budget describes the applied water demand by crops within the SLO Basin. These crop types included citrus, deciduous (non -vineyard), pasture, vegetable, vineyard, and turfgrass. Estimates of per -acre annual water demand are shown in the table below: Table 9-5. Consumptive Use of Applied Water and Total Irrigated Acreage by Land Use/Land Cover Type Land Use/ Land Cover Acre-feet per acre per year Acreage Low Med High 2018 Citrus 1.1 1.6 2.2 256 Deciduous 1.8 2.2 2.5 20 Pasture 2.6 3.1 3.7 41 Vegetables' 1.4 1.6 2 768 Vineyard 0.5 0.6 0.8 1 2410 Turfgrassz 2 2.6 4.1 164 160 percent of ET applied water to account for fallow fields 2Turfgrass represents irrigated turf i.e. lawns, golf courses, etc... As shown above, crop types use different quantities of water per year and the conversion from a less efficient crop would reduce the overall groundwater demand. This voluntary water efficient crop conversion program will be included in the Demand Management Plan. 9.5.3.4 Volunteer Land Fallowing The Voluntary Fallowing Program will create a process to convert high water use irrigated agricultural lands to low water use open space or other less water intensive land use on a voluntary basis. The program would be similar to the volunteer water efficient crop conversion program and the resulting benefit would depend on the initial crop type. This voluntary fallowing program will be included in the Demand Management Plan. 9.5.3.5 Pumping Reductions The projects and management actions described above are developed to maintain groundwater levels above minimum thresholds through in -lieu pumping reductions or increased recharge. The Demand Management Plan prioritizes the development of water conservation measures, irrigation efficiencies, volunteer water efficient crop conversion and the volunteer fallowing of crops to avoid mandatory direct pumping reductions. Mandatory pumping reductions may be required if the criteria for undesirable results for the sustainability indicators as described in Chapter 8 is met. The implementation of the mandatory direct pumping reductions will be addressed in the Demand Management Plan. 39 Page 462 of 1183 SLO Basin Groundwater Sustainability Plan Projects and Management Actions (§ 354.44) County of SLO and City of SLO 9.6 ADAPTIVE MANAGEMENT (§ 354.44A) Adaptive management allows the GSAs to react to the success or lack of success of actions and projects implemented in the Basin and to make management decisions to redirect efforts in the Basin to more effectively achieve sustainability goals. The GSP process under SGMA requires annual reporting and updates to the GSP at minimum every 5 years. These requirements provide opportunities for the GSAs to evaluate progress towards meeting its sustainability goals and avoiding undesirable results. Adaptive management triggers are thresholds that, if reached, initiate the process for considering implementation of adaptive management actions or projects. For SLO Bain, the trigger for adaptive management is the following: • If analytical or modeled projections anticipate that future conditions will exceed the undesirable result thresholds, then the preparation for implementation of additional projects and management actions would begin. If actual conditions exceed the undesirable result thresholds, then additional projects and management actions will be implemented. .81 Page 463 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO 10 IMPLEMENTATION PLAN Implementation Plan This section is intended to serve as a conceptual roadmap for each Groundwater Sustainability Agency (GSA) to start implementing the Groundwater Sustainability Plan (GSP) over the first five years and discusses implementation effects in accordance with the Sustainable Groundwater Management Act (SGMA) regulations sections 354.8(f)(2) and (3). A general schedule showing the major tasks and estimated timeline for the GSP implementation is provided in Figure 10-1. The implementation plan provided in this chapter is based on current understanding of SLO Basin (Basin) conditions and includes consideration of the projects and management actions included in Chapter 9, as well as other actions that are needed to successfully implement the GSP including the following: • GSP implementation, administration, and management • Funding • Reporting, including annual reports and 5-year evaluations and updates 10.1 GSP IMPLEMENTATION, ADMINISTRATION, AND MANAGEMENT 10.1.1 Administrative Approach/Governance Structure The City and County (GSAs) and the participating parties will continue to operate under the existing MOA, including the existing governance structure, until actions are taken amending/revising the existing MCA or developing new agreements (e.g., joint power agreement). The existing MOA is included in Appendix A and will automatically terminate upon DWR's approval of the GSP for the Basin. During DWR's GSP review process, the GSAs intend to update the governance structure before the GSP is approved to better serve the implementation of the GSP. For example, the updated governance structure could be established through a new agreement between the GSAs that supersedes the existing MCA. The agreement would outline details and responsibilities for GSP administration and implementation among the participating entities and may include provisions to establish other advisory bodies to advise the GSAs on GSP implementation, updates, etc. 10.1.2 Implementation Schedule Figure 10-1 illustrates the GSP implementation schedule. Included in the chart are activities necessary for ongoing GSP monitoring and updates, as well as tentative schedules for the development of projects and management actions. Additional details about the activities included in the schedule are provided in these activities' respective sections of this GSP. Adaptive management and mandatory demand management would only be implemented if triggering events are reached, as described in Chapter 9, and are shown as ongoing in the schedule. 41 Page 464 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO _ 1 2 Task Name San Luis Basin GSP Implementation GSP Approval Plan Submittal to DWR DWR Review and Approval Administration and Finance Administrative Approach/Governance Structure Duration 5208 days 490 days 0 days 24 mans 5200 days 12 mans Start 2020 Mon 1/31/22 Mon 1/31/22 Mon 1/31/22 Mon 1/31/22 Mon 1/31/22 Mon 1/31/22 3 4 5 6 7 Financing Plan Fee Study 5200 days 12 mans Mon 1/31/22 Mon 1/31/22 8 9 Funding Mechanism Implementation 12 mans Mon 1/2/23 10 Fee Collection 236 mons Mon 12/4/23 11 Public Coordination and Outreach 248 mons Mon 1/2/23 12 Adaptive Management Management Action Implementation Demand Mangement Plan Demand Management Implementation Monitoring Network Implementation Groundwater Metering and Reporting Plan Develop Monitoring Program 260 mons 5200 days 24 mans 236 mans 5200 days 12 mons 12 mans Mon 1/31122 Mon 1/31/22 Mon 1/31/22 Mon 12/4/23 Mon 1/31/22 Mon 1/31/22 Mon 1/31/22 13 14 15 16 17 18 19 Monitoring Program 248 mons Mon 1/2/23 20 Project Implementation 5200 days Mon 1/31/22 21 Supplemental Water Feasibility Study 12 mons Mon 1/31/22 22 Agreement Negotiation 6 mons Mon 1/2/23 23 PI anning/Design 12 mans Mon 6/19/23 24 Construction Operation Reporting Annual Reports 5-Yr G5P Evaluation/Update Evaluate/Refine SMCs 12 mans 218 mans 5209 days 4956 days 5208 days 260 mons Mon 5/20/24 Mon 4/21125 Mon 1/31/22 Fri 4/1/22 Mon 1131/22 Mon 1/31/22 25 26 27 4B 49 50 Update Integrated Model 260 mons Mon 1/31/22 51 5-Yr Report/GSP Evaluation/Integrated Model 0 days Thu 4/1/27 Update 1 5-Yr Report/GSP Evaluation/Integrated Model 0 days Thu 4/1/32 52 Update 2 5-Yr Report/GSP Evaluation/Integrated Model 0 days Wed 4/1/37 53 Update 3 54 GSP Updates (if needed) 193 mons Thu 4/1/27 Implementation Plan 2022 M23 2024 1 2025 1 2026 2027 2028 1 2029 2030 2031 1 2032 2033 - 2034 1 2035 , 2036 2037 1 2038 1 2039 2040 1 2041 1 2042 2043 r2s 1 1 lmm1 0 o a o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Page l 4/1 411 4/1 Figure 10-1. SLO Basin GSP Implementation Schedule 42 Page 465 of 1183 SLO Basin Groundwater Sustainability Plan Implementation Plan County of SLO and City of SLO 10.1.3 Implementation Costs Implementation of this GSP is estimated to cost approximately $965,000 per year for the first five years of implementation, excluding the development of the specific projects listed in Chapter 9. Costs related to the various activities anticipated for the first five years are shown in Table 10-1. Estimates of future annual implementation costs (Years 6 through 20) will be developed during future updates of the GSP, which will include the development of the various anticipated projects. The costs of specific projects and management actions will like vary year by year, based in part on needed adaptive management activities. 10.1.3.1 Administration and Finance The Administration and Finance implementation activities include the following: GSP Administration Development, Ongoing GSP Implementation, Fee Study, Funding Mechanism Implementation, Demand Management Plan. The total estimated cost during the initial five years of the GSP implementation is approximately $2,850,000 and is shown in Table 10-1. It is anticipated that the Administrative and Finance Costs will be paid for by regulatory fees and will be analyzed as part of the fee study as described in Section 10.2.2. 10.1.3.2 Monitoring Network Implementation The Monitoring Network Implementation includes the development of a groundwater metering and reporting plan, development of a monitoring program, and conducting annual monitoring. The Groundwater Metering and Reporting Plan is described in detail in Section 9.5 Management Actions and will provide a key metric to evaluate the effectiveness of the demand management strategies and enable the GSAs to adaptively manage the Basin. The monitoring program is described in detail in Chapter 7- Monitoring Network and the expansion of the monitoring network is targeted to monitor changes to groundwater and surface water conditions relative to SMCs within the Basin. The annual monitoring is the execution of the data collection required to complete the Annual Reports. The total estimated cost during the initial five years of the GSP implementation is approximately $875,000 as shown in Table 10-1. It is anticipated that the Monitoring Network Implementation will be paid for by regulatory fees and will be analyzed as part of the fee study as described in Section 10.2.2. 10.1.3.3 Project Implementation Project implementation is anticipated to include the following steps: Supplemental Water Feasibility Study; Planning and Design; Construction and Operation. The initial step for project implementation is anticipated to include completion a Supplemental Water Feasibility Study to further evaluate the different supplemental water supply options (e.g. SWP, Recycled Water, Price Canyon Discharge Water, etc.) described in Chapter 9. This evaluation will include a more granular analysis of the parameters associated with each of the different supplemental supply options available to address the overdraft in the basin, including assessment of seasonal supply availability and demand patterns, hydraulic capacity, costs of supplemental water, environmental/permitting requirements, and updated infrastructure and operation & maintenance costs. The feasibility study will also include additional groundwater model scenario analysis to further determine beneficiaries of the individual projects to assist in developing equitable project cost sharing mechanisms. The findings from the Supplemental Water Feasibility Study will be utilized to inform agreement negotiations and planning/design of the preferred supplemental water supply projects for the basin. It is anticipated that the Projects will be paid for by project proponents/beneficiaries and costs associated with project implementation is not included in the GSP Implementation Budget estimate shown in Table 10-1. Specific details regarding the cost share mechanisms are anticipated to be determined after the preferred supplemental water projects are identified and further defined. Additionally, it is anticipated that grant funding would be available to assist with project implementation, see Section 10.2.3. 43 Page 466 of 1183 SLO Basin Groundwater Sustainability Plan Implementation Plan County of SLO and City of SLO 10.1.3.4 Reporting SGMA regulations require the GSAs to submit annual reports to DWR on the status of GSP implementation. The reporting requirements are presented in Section 10.3.1. SGMA regulations require the GSAs to evaluate the GSP at least every 5 years and whenever the Plan is amended. The reporting requirements for the periodic evaluation are presented in Section 10.3.2. The initial 5-year GSP evaluation is due for submission to DWR in April 2027. The estimated cost to prepare an annual report is $100,000/year and the cost for the initial Five Year GSP update is estimated to be $500,000, equating to a total of $1,000,000 over the initial five years of the GSP implementation. It is anticipated that the Reporting Costs will be paid for by regulatory fees and will be analyzed as part of the fee study as described in Section 10.2.2. 10.1.4 Outreach and Communication To meet the requirements of SGMA, implementation of the GSP will require additional communication and outreach efforts and coordination among the City and County GSAs and stakeholder groups. The GSP calls for GSAs to routinely provide information to the public about GSP implementation and ongoing sustainable management of the Basin. The GSP calls for a website to be maintained as a communication tool for posting data, reports, and meeting information. The website may also include forms for on-line reporting of information needed by the GSAs (e.g., annual pumping a shown in mounts) and an interactive mapping function for viewing Basin features and monitoring information. 10.2 FUNDING The budget information included in Section 10.1.3 will be used to conduct a fee study which could include development of funding mechanisms to cover the costs of implementing the regulatory programs described in the GSP. This fee could include costs related to monitoring and reporting, hydrogeologic studies, pumping reduction enforcement if necessary, public outreach, and other related costs. Project implementation costs are anticipated to be covered by the project proponents and the associated beneficiaries. Project implementation costs will be evaluated as part of the Supplemental Water Feasibility Study. 10.2.1 GSP Implementation Funds Development of this GSP was partially funded through a Proposition 1 Sustainable Groundwater Planning Grant from DWR, along with in -kind contributions from the GSAs and GSC members. Although ongoing implementation of the GSP could include contributions from its member agencies, which are ultimately funded through customer fees or other public funds, additional funding would be required to implement the GSP. Included in the GSP implementation is a Fee Study that will evaluate multiple approaches for funding the ongoing administration and implementation of the GSP. 10.2.2 Fee Study The GSAs plan to perform a fee study to evaluate and provide recommendations for developing GSP implementation funding mechanisms. This study will include focused public outreach and meetings to educate and solicit input on the potential fee structures/funding mechanisms (i.e. pumping fees, assessments, or a combination of both). California Water Code Sections 10730 and 10730.2 provide GSAs with the authority to impose certain fees, including fees on groundwater pumping. Any imposition of fees, taxes or other charges would need to follow the applicable protocols outlined in the above referenced water code sections and all applicable Constitutional requirements based on the nature of the fee. It is anticipated that the fee study will cover the costs associated with the Administrative and Finance, Monitoring Network Implementation, and Reporting. The Fee Study is not anticipated to cover the costs associated with project implementation. 10.2.3 Grant/Low Interest Financing The GSAs will pursue grants and low -interest financing to help pay for GSP implementation costs to the extent possible. If grants or low -interest financing is obtained for GSP implementation it could be utilized to Page 467 of 1183 SLO Basin Groundwater Sustainability Plan Implementation Plan County of SLO and City of SLO offset costs for the GSAs and basin pumpers. However, as mentioned previously external funding/financing may only be eligible for project and management action implementation and not ongoing GSP administrative expenses. 1[I1i11111NPillZ11IN9I►D4 As part of GSP implementation, SGMA Regulation §356.2 requires the GSAs to develop annual reports and more detailed five-year evaluations, which could lead to updates of the GSP. The following sections describe the reporting requirements for both the annual reports and five-year evaluations. 10.3.1 Annual Reports Annual reports will be developed to address current needs in the Basin and the legal requirements of SGMA. As defined by DWR, annual reports must be submitted for DWR review by April 1st of each year following the GSP adoption, except in years when five-year or periodic assessments are submitted. Annual reports are anticipated to include three key sections: General Information, Basin Conditions, and Implementation Progress. The GSAs will compile information relevant to annual reports and the Basin Point of Contact will coordinate collection of information and submit a single annual report for the Basin to DWR. 10.3.1.1 General Information The General Information section will include an executive summary that highlights the key content of the annual report. This section will include a map of the Basin, a description of the sustainability goals, a description of GSP projects and their progress, as well as an annual update to the GSP implementation schedule. 10.3.1.2 Basin Conditions Basin conditions will describe the current groundwater conditions and monitoring results in the Basin. This section will include an evaluation of how conditions have changed over the previous year and will compare groundwater data for the water year to historical groundwater data. Pumping data, effects of project implementation (if applicable), surface water deliveries, total water use, and groundwater storage data will be included. Key required components include: • Groundwater level data from the monitoring network, including contour maps of seasonal high and seasonal low water level maps • Hydrographs of groundwater elevation data at RMS • Groundwater extraction data by water use sector • Groundwater Quality at RMS • Surface water supply availability and use data by water use sector and source • Streamflow • Total water use data • Change in groundwater in storage, including maps for the aquifer • Subsidence rates and associated survey data 10.3.1.3 Implementation Progress Progress toward GSP implementation will be included in the annual report. This section of the annual report will describe the progress made toward achieving interim milestones as well as implementation of projects and management actions. Key required components include: • GSP implementation progress, including proposed changes to the GSP • Progress toward achieving the Basin sustainability goals 45 Page 468 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Table 10-1 GSP Implementation Costs (2022-2027) Implementation Plan GSP Implementation Activity Description Estimated Cost Unit Anticipated Timeframe Estimated Costs (2022 -2027) Administrative and Finance GSP Administration Development Develop Administrative Approach/Governance Structure for GSP Implementation $100,000 Lump Sum Q1-4, 2022 $100,000 Ongoing GSP Implementation Routine GSP Administration (including staffing, overhead expenses, equipment, outreach and communication, etc.) $500,000 Annual 2021 - 2025 $2,500,000 Fee Study Prepare a fee study to evaluate and provide recommendations for GSP implementation funding mechanisms $150,000 Lump Sum Q1-4, 2022 $150,000 Funding Mechanism Implementation Implement and begin collecting GSP Implementation fees $100,000 Lump Sum Q1-4, 2023 $100,000 Demand Management Plan The demand management plan will include the documentation of water conservation measures, and develop programs for volunteer water efficient crop conversion, volunteer fallowing of crops, and pumping reductions, etc. in a stakeholder driven process. $100,000 Lump Sum 2022 - 2023 $100,000 Monitoring Network Implementation Groundwater Metering and Reporting Plan Develop a plan to establish and maintain a groundwater pumping, metering, and reporting plan (does not include meters and installation) $150,000 Lump Sum Q1-4, 2022 $150,000 Conduct survey of proposed monitoring well network to verify locations and elevations, and video logging if applicable $100,000 Lump Sum Q1-4, 2022 $100,000 Monitoring Program Construction of 5 new monitoring wells and 5 surface water gages for GDEs and GW/SW interaction, transducers and surveying $500,000 Lump Sum Q1-4, 2022 $500,000 Annual Monitoring I Complete annual monitoring (Field work) $25,000 Annual Q1-4, 2022 $125,000 Project Implementation Supplemental Water Feasibility Study Costs estimates for the Supplemental Water Feasibility Study, Planning/Design and Construction of Supplemental Water Projects not included in the initial 5-Yr budget. Planning/Design Construction Reporting Annual Reports Compile data and prepare GSP Annual Report $100,000 Annual 2021 - 2025 $500,000 5-Yr GSP Updates Compile data and prepare 5-yr GSP Updates, including Integrated Model updates $500,000 Lump Sum Q2, 2026 - Q1, 2027 $500,000 Total Estimated Costs (2022 - 2027) $4,825,000 Average Annual Estimated Cost (2022 - 2027) $965,000 Em Page 469 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Implementation Plan Development of an annual report will begin following the end of the water year, September 30, and will include an assessment of the previous water year. The annual report will be submitted to DWR before April 1st of the following year. The 2021 annual report covering water year 2021 will be submitted by the GSAs by April 1, 2022. Five annual reports for the Basin will be submitted to DWR between 2022 and 2026, prior to the first five-year assessment of this GSP, which is to be submitted to DWR in January 2027. 10.3.2 Five -Year Evaluation Reports As required by SGMA regulations, an evaluation of the GSP and the progress toward meeting the approved sustainable management criteria and the sustainability goal will occur at least every five years and with every amendment to the GSP. A written five-year evaluation report (or periodic evaluation report) will be prepared and submitted to DWR. The information to be included in the evaluation reports is provided in the sections below. 10.3.2.1 Sustainability Evaluation A Sustainability Evaluation will contain a description of current groundwater conditions for each applicable sustainability indicator and will include a discussion of overall sustainability in the Basin. Progress toward achieving interim milestones and measurable objectives will be included, along with an evaluation of status relative to minimum thresholds. If any of the adaptive management triggers are found to be met during this evaluation, a plan for implementing adaptive management as described in Section 9.6 of this GSP will be included. 10.3.2.2 Plan Implementation Progress A Plan Implementation Progress section will describe the current status of project and management action implementation and whether any adaptive management actions have been implemented since the previous report. An updated project implementation schedule will be included, along with any new projects identified that support the sustainability goals of the GSP and a description of any projects that are no longer included in the GSP. The benefits of projects and management actions that have been implemented will be described and updates on projects and management actions that are underway at the time of the report will be documented. 10.3.2.3 Reconsideration of GSP Elements As additional monitoring data are collected, land uses and community characteristics change, and GSP projects and management actions are implemented, it may become necessary to reconsider elements of this GSP and revise the GSP as appropriate. GSP elements to be reassessed may include basin setting, management areas, undesirable results, minimum thresholds, and measurable objectives. If appropriate, a revised GSP, completed at the end of the five-year assessment period, will include revisions informed by findings from the monitoring program and changes in the Basin, including changes to groundwater uses, demands, or supplies, and results of project and management action implementation. 10.3.2.4 Monitoring Network Description A description of the monitoring network will be provided. An assessment of the monitoring network's function will be included, along with an analysis of data collected to date. If data gaps are identified, the GSP will be revised to include a method for addressing these data gaps, along with an implementation schedule for addressing gaps and a description of how the GSA will incorporate updated data into the GSP. 10.3.2.5 New Information New information available since the last five-year evaluation or GSP amendment will be described and evaluated. If the new information should warrant a change to the GSP, this will also be included, as described previously in Reconsideration of GSP Elements. 47 Page 470 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Implementation Plan 10.3.2.6 Regulations or Ordinances A summary of the regulations or ordinances related to the GSP that have been implemented by DWR or others since the previous report will be provided. The report will include a discussion of any required updates to the GSP. 10.3.2.7 Legal or Enforcement Actions Legal or enforcement actions taken by the GSA in relation to the GSP will be summarized, including an explanation of how such actions support sustainability in the Basin. 10.3.2.8 Plan Amendments A description of amendments to the GSP will be provided in the five-year evaluation report, including adopted amendments, recommended amendments for future updates, and amendments that are underway. 10.3.2.9 Coordination Ongoing coordination will be required among the GSA, members of the GSC, and the public. The five-year evaluation report will describe coordination activities between these entities such as meetings, joint projects, data collection and sharing, and groundwater modeling efforts. 10.3.2.10 Reporting to Stakeholders and the Public Outreach activities associated with the GSP implementation, assessment, and GSP updates will be documented in the five-year evaluation report. M] Page 471 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO REFERENCES Implementation Plan Association for the Advancement of Cost Engineering, Inc. 2011. ACE International Recommended PracticeNo. 17R-97; Cost Estimate Classification System; TCM Framework: 7.3 - Cost Estimating and Budgeting. 2011. Balance Hydrologics. 2008. Hydrology and Geology Assessment of the Pismo Creek Watershed, San Luis Obispo County, California. 2008. Blaney. 1963. Utilization of the Water of the Santa Ynez River Basin in Southern Santa Barbara County California, United Stated Deparment of Agriculture. 1963. -. 1933. Ventura County Investigation, Bulletin No. 46, California Deparment of Public Works, Division of Water Resources. 1933. Boyle Engineering. 1991. City of San Luis Obispo Groundwater Basin Evaluation. January. 1991. Carollo. 2012. San Luis Obispo County Master Water Report. 2012. CCWA. 2021. Water Management Strategy. 2021. CIMS. 2019. Station 52, San Luis Obispo - Central Coast Valleys. 2019. City of San Luis Obispo. 2016.2015 Urban Water Management Plan. 2016. -. 2018. General Plan. 2018. -. 2015. Water Resources Status Report. 2015. -. 2000. Water Use Factors. 2000. Cleath & Associates, Inc. 2001. Well Construction and Testing Report for Lewis Lane #4, Edna Valley, San Luis Obispo County. Prepared for Southern California Water Company. July. 2001. -. 2003. Well Construction and Testing Report for Water Supply and Irrigation Wells, City of San Luis Obispo, Hayashi Irrigation Wells and Highway 101 Water Supply Well. March. 2003. Cleath-Harris Geologists. 2018. Groundwater Flow Analysis, Recycled Water Recharge Project, San Luis Valley Subarea, San Luis Obispo Valley Groundwater Basin. 2018. -. 2019. Optional Task 2.4B Geophysical Survey. 2019. Cleath-Harris Geologists, Inc. 2010. Edna Valley Water System Groundwater Study. Prepared for Golden State Water Company. May. 2010. -. 2013. Summary of Drilling,. Testing, and Destruction of the Golden State Water Company Country Club Test Well, Edna Road System, 6110 Lewis Lane, San Luis Obispo, California. Prepared for Golden State Water Company. June. 2013. -. 2013. Summary of Exploration and Testing, 5061 Hacienda Avenue, San Luis Obispo, California. Prepared for Golden State Water Company. February. 2013. -. 2014. Summary of Exploration and Testing, Blodgett parcel, Whiskey Run Lane, Country Club Area, San Luis Obispo, California. Prepared for Golden State Water Company. July. 2014. County of San Luis Obispo. 2014. San Luis Obispo County Integrated Regional Water Management Plan (1 RWMP). 2014. CSLRCD, Coastal San Luis Resource Conservation District. 2014. Mitigated Negative Declaration/Initial Study Edna Valley Groundwater Basin Recharge and Steehead Habitat Enhancement Project. 2014. Cuesta Engineering Corporation. 2007. San Luis Obispo Creek Watershed Calibration Study. 2007. Dibble, T.W. 2004. Geologic Map of the Lopez Mountain Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2004. #DF-130. Dibblee, T.W. 2006. Geologic Map of the Arroyo Grande NE Quadrangle, San Luis Obispo County, California. s.l.: Dibble Geology Center Map, 2006. #DF-211. -. 2006. Geologic Map of the Pismo Beach Quadrangle, San Luis Obispo County, California. s.l.: Dibblee Geology Center Map, 2006. #DF-212. -. 2004. Geologic Map of the San Luis Obispo Quadrangle, San Luis Obispo County, California.. s.l.: Dibble Geology Center Map, 2004. #DF-129. DWR. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. . • Page 472 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Implementation Plan -. 2016. California's Groundwater: Bulletin 118 - Interim Update 2016, Working Towards Sustainability. 2016. -. 2003. California's Groundwater: Bulletin 118 - Update 2003, Groundwater Basin Descriptions. 2003. -. 2015. Consumptive Use Program Plus (CUP+) Model, in California Water Plan Update 2013, Volume 4. Reference Guide, Developed by DWR and UC Davis. 2015. -. 2014. DWR Atlas - Aglricultural Lang Use and Irrigated Areas. [Online] 2014. gis.water.ca.gov. -. 1964. San Luis Obispo and Santa Barbara Counties Land and Water Use Survey, 1959.. s.l.: California Department of Water Resources (DWR), 1964. -. 1958. San Luis Obispo County Investigation. State Water Resources Board Bulletin No. 18.. s.l. California Department of Water Resources (DWR). May., 1958. -. 1997. San Luis -Edna Valley Groundwater Basin Study, Draft Report.. s.l.: California Department of Water Resources (DWR)., 1997. -. 1996. South Central Coast Land Use Survey. 1996. -. 1987. Southern Central Coast Land Use Survey, 1985. Morro Bay South 54-30 and San Luis Obispo 54-31 Survey Maps. 1987. -. 2019. Sustainable Groundwater Management Act 2019 Basin Prioritization - Process and Results Document. 2019. -. 2016. Water Budget Best Management Practices for the Sustainable Management of Groundwater. 2016. -. 2002. Water Resources of the Arroyo Grande - Nipomo Mesa Area. 2002. DWR, California Department of Water Resources. 2019. Delivery Capability Report and Studies 2019. 2019. EPA. 2008. Water Sense Factsheet - Indoor Water Use in the United States, EPA-832-F-06-004. 2008. ESA Consultants, Inc. 1994. Hydrologic Investigation, Edna Valley Well Location Study. September. 1994. Fugro West and Cleath & Associates. 2002. Paso Robles Groudnwater Study, Final Report. 2002. GSI Water Solutions. 2018. San Luis Obispo Valley Basin Characterization and Monitoring Well Installation. 2018. GSWC. 2015. Staged Mandatory Conservation and Rationing Plan. 2015. Hall, C.A. 1979. Geologic map of the San Luis Obispo -Son Simeon Region, California. s.l.: U.S. Geological Survey, 1979. Map 1-1097. -. 1973. Geology of the Arroyo Grande Quadrangle, California.. s.l.: California Division of Mines and Geology, 1973. Map Sheet 24. ITRC. 2020. Official Cal Poly Precipitation Data, Cal Poly/NOAA Station Rain Gage. 2020. Johnson, A.I. 1967. Specific Yield - Compilation of Specific Yield for Various Materials, U.S. Geological Survey Water -Supply Paper 1662-D, prepared in cooperation with the California Deparment of Water Resources. 1967. National Land Cover Database. Multi -Resolution Land Characteristics Consortium. 2016. Multi -Resolution Land Characteristics Consortium. Rosenberg, L.I. 2001. Potential Aquifer Recharge Areas: Monterey County, California. s.l.: Monterey County Planning Department, 2001. San Luis Obispo County Deparment of Agriculture/Weights and Measures. 2019. Crop Surveys for San Luis Obispo Valley Groundwater Basin 2013-2018. 2019. San Luis Obispo County Department of Public Works. 2020. Andrews Street Bridge Stream Flow Gage 745. 2020. -. 2020. Gas Company Rain Sensor 3099. 2020. San Luis Obispo County Engineering Department. 1974. Hydrologic & Climatological Data, Seasons of 1970-71 & 1971-72. 1974. SLO-FCWCD. 2014. CASGEM Monitoring Plan for High and Medium Priority Groundwater Basins in the San Luis Obispo County Flood Control & Water Conservation District. September. s.l.: San Luis Obispo Flood Control & Water Conservation District, 2014. 50 Page 473 of 1183 SLO Basin Groundwater Sustainability Plan County of SLO and City of SLO Implementation Plan Stillwater Sciences. 2015. Percolation Zone Study of Pilot -Study Groundwater Basins in San Luis Obispo County, California. September. 2015. SWRCB. 1990. Ernest Righetti & Sons Application 28883, Decision 1627. 1990. TEAM Engineering & Management. 2000. Groundwater Yield Analysis. July. 2000. USBR. 1955. Reconnaissance Report San Luis Obispo County Basin, California.. s.l.: U.S. Bureau of Reclamation, Region 2, Sacramento., 1955. USDA-NRCS. 2007. Soil Survey Geographic Database (SSURGO). s.l.: U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2007. Wallace Group. 2020. Policy Considerations for Groundwater Sustainability Plan. 2020. WSC. 2018. Salinas and Whale Rock Reserviors Safe Annual Yield TM. 2018. 51 Page 474 of 1183 Item 6 GtT Y O.� CouncilAgenda Report Department Name: Cost Center: For Agenda of: Placement: Estimated Time: FROM: Aaron Floyd, Utilities Director Prepared By: Mychal Boerman, Utilities Deputy Director - Water Utilities 6001 December 8, 2020 Consent NA SUBJECT: SUSTAINABLE GROUNDWATER MANAGEMENT ACT (SGMA) GROUNDWATER SUSTAINABILITY PLAN UPDATE RECOMMENDATION Acting as the City of San Luis Obispo Groundwater Sustainability Agency, receive and file an update on Sustainable Groundwater Management Act (SGMA) Groundwater Sustainability Plan (GSP) development, including the Draft Communication and Engagement Plan, Draft Data Management Plan, and Draft Chapters 1-6 of the Groundwater Sustainability Plan. REPORT -IN -BRIEF This report briefly outlines Sustainable Groundwater Management Act requirements related to the production of a Groundwater Sustainability Plan and briefly describes the first six Draft Groundwater Sustainability Plan chapters, as well as associated technical memos and supporting documents. Key initial findings indicate that the portion of the groundwater basin which underlays the City has not experienced continued lowering of groundwater levels, or other undesirable results that are generally associated with Sustainable Groundwater Management Act regulations. However, adjacent portions of the groundwater basin in the Edna Valley area have experienced continued groundwater level decline and will require groundwater basin management actions such as reductions in groundwater pumping, increased conservation, improved irrigation efficiency, agricultural irrigation reductions, and/or water supply augmentation projects. With continued stakeholder input, quantifiable management actions will be defined within the upcoming Groundwater Sustainability Plan chapters and will be returned to the City of San Luis Obispo Groundwater Sustainability Agency for adoption in early 2022. DISCUSSION Background The Sustainable Groundwater Management Act (SGMA) requires sustainable groundwater management in all high and medium priority groundwater basins, including the high priority San Luis Obispo Valley Groundwater Basin (SLO Basin). The SLO Basin, which underlays the City ItIL Figure I - Overview of the SLO Basin Packet PagelTf lof 1183 Item 6 and unincorporated areas outside of the City, was designated high priority by the State due to several factors including the documented lowering of groundwater levels in the eastern portion of the basin, near Edna Valley, and the relatively large number of people overlying the basin in the western (City of San Luis Obispo) portion of the basin. SGMA first required the formation of Groundwater Sustainability Agencies (GSAs) by June 2017. The City of San Luis Obispo (City) and the County of San Luis Obispo (County), completed the GSA formation process, resulting in full coverage of the SLO Basin. The City and County GSAs are working together to develop a Groundwater Sustainability Plan (GSP) that covers the entire SLO Basin. This Groundwater Sustainability Plan needs to be adopted by January 31, 2022. Once adopted by both the City and the County GSAs, and approved by Department of Water Resources (DWR), implementation of the Groundwater Sustainability Plan will occur and will include quantifiable objectives and will achieve groundwater sustainability by 2042. A Groundwater Sustainability Commission (GSC), comprised of significant potential users of groundwater in the SLO Basin, was formed as an advisory body to the City and County GSAs. On the recommendation of this Groundwater Sustainability Commission, this report is intended to inform the City GSA and public on the progress made to date in the development of the Groundwater Sustainability Plan. 11112015: 3131116: SGUA Boundary enacted modification Communication and Engagement Plan Public engagement and stakeholder involvement will be critical to the success of a Groundwater Sustainability Plan. The Communication and Engagement Plan (C&E Plan) (Attachment A) describes the planned activities for engaging interested parties in SGMA implementation efforts in the San Luis Obispo Valley Basin. 6/3012017: 113112022: Goal: Establish Adopt Aohieve GSA GSP sustainability Figure 2 - SGMA Timeline Public vyabW ''"—LOC81 Land Systems ntitle use ntonitoring Planning Planing reporting on groundwater Ag.elevations Agricultural tigers Holdets of a erlying Dlsad, groundwater Other communities rights Interested Domestic users Parties Environmental Native useas of American groundwater tribes Surface water users Fetle ral {if sv4►�s.slacouutlratet:©rg/sgma hydrologic 9+`"1ent cvnnecdan, Figure 3 — SGMA Stakeholders Packet PaljWf 1183 Item 6 It is designed to meet the stakeholder engagement requirements of SGMA and GSP regulations while ensuring local stakeholders are educated, engaged, and given opportunities to participate and to provide feedback. The general purpose of the C&E Plan is to facilitate effective communication and engagement with the multiple and varied stakeholders in the San Luis Obispo Valley Basin. The C&E Plan outlines programs designed to engage stakeholders through a series of public workshops, opportunities for comment at public meetings, education through quarterly digital newsletters, and the use of a user-friendly Groundwater Communication Portal that acts as a hub for SGMA related communications and engagement opportunities. Although COVID-19 related closures have impacted the ability for in -person workshops, public participation has increased through the utilization of virtual meetings during the pandemic. Data Management Plan Development of a Data Management System (DMS) is required to ensure adequate groundwater data tracking per SGMA regulations. This data includes well locations, water level data, and well construction information. The City GSA and County GSA opted to draft a Data Management Plan (DMP) (Attachment B) to capture SGMA data handling requirements, identify data needs and sources, describe the data structure that will be used, and outline the process for collection, review, and upload of data. Since each groundwater basin that is subject to SGMA has twenty years to achieve sustainability, well thought out and well documented data management will be essential to achieving compliance as an organization experiences technological and staffing changes over time. Brief Summary of GSP Chapters 1-6 The chapter summaries presented in this report are draft chapters and are subject to change as comments are received from local agencies and the public regarding the contents. Full chapters are provided as attachments to this staff report and are as follows: Chapter 1: Introduction to the SLO Basin GSP (Attachment C) Chapter 2: Agency Formation (Attachment C) Chapter 3: Description of Plan Area (Attachment D) Chapter 4: Basin Setting (Attachment D) Chapter S: Groundwater Conditions (Attachment E) Chapter 6: Water Budget (Attachment F) Chapter 1: Introduction to the SLO Basin GSP Chapter 1 is largely administrative in nature and is designed to give the reader background information related to why the GSP is being developed. This chapter outlines the purpose of developing the GSP, a high level description of the SLO Basin, and an explanation of how the Department of Water Resources prioritizes basins throughout the state and why the SLO Basin is categorized as a high priority basin. The reader will find information in this chapter that will set the stage for a better understanding of the need for a GSP. Packet Page4l/13)f 1183 Item 6 Chapter 2 - Agency Formation Chapter 2 of the GSP outlines agency information and management structure, including information related to the creation of the City Groundwater Sustainability Agency and the County of San Luis Obispo Groundwater Sustainability Agency. This chapter also discusses the formation of the Groundwater Sustainability Commission, which acts as an advisory body to the City GSA and County GSA, as well as the development of a Memorandum of Agreement (MOA) between the two agencies (Attachment G). The MOA's purpose is for the City GSA and County GSA, with input from other GSC members, to coordinate in the preparation of a single GSP for the entire SLO Basin. Figure 4 below demonstrates the governance structure outlined in the MOA. It is important to note that the City GSA and County GSA are responsible for independently adopting the GSP and implementing the GSP within their respective service areasl. 0 9W CrrYOFSLO GSA A COUNTY OF SLO GSA MYCHALSOERMAN 6SA S IAfF DICKTZOU, FE 0 rryDreVGrpfWWer. Wow Rrsawres �rrs�nr, CrUy of Sam Luis OhhpD County of Smn Luis obkpa ON " EDOA VALLEY GROWERS V�-- M WC ANDY PEASE BOBSCHIEBELHUT BRUCE GIRSON AAR'ON FLOYD GEORGE nOHATI Affernate Atrrmare Mremmfe EDNA RANCHAND VARIAN RANCFI MWr- DENN IS FERNAN DEZ h4emk'er JAMES I.OKEY Akcmp re MARK ZIMMER V re ckm'r TORY MOOR E Ah rrsmrn Figure 4 — Local SGMA Governance Structure Chapter 3: Description of Plan Area Chapters 3 provides an introduction to the SLO Basin with a description of the jurisdictional areas that overlie the basin, details about existing City and County land use plans, density of groundwater wells within the basin, and a detailed description of active groundwater and surface water monitoring and management programs. Not unlike Chapter 1 and Chapter 2, this chapter helps document information that will assist in decision making as subsequent GSP chapters are developed. I City and County GSP adoption requires a simple majority vote. Packet PalMf 1183 Item 6 Chapter 4: Basin Setting Chapter 4 of the GSP is a technical chapter that describes the regional and local basin geology, groundwater aquifer information, and surface water body information. This chapter defines the physical extent and limitations of the SLO Basin as well as the importance of how surface water and groundwater interact locally. Various maps within the chapter document details about the groundwater basin such as infiltration rates within different areas of the basin, bedrock elevations, and land subsidence risk. Additionally, this chapter provides a series of cross - sectional diagrams that document the various types of geologic layers of different parts of the SLO Basin. Chapter 5: Groundwater Conditions Following SGMA regulations, Groundwater Sustainability Agencies must develop and implement a Groundwater Sustainability Plan for managing and using groundwater without causing six specific undesirable results. These undesirable results are defined as: the chronic lowering of groundwater elevations, groundwater storage reductions, seawater intrusion, land subsidence, the depletion of interconnected surface waters, and the degradation of groundwater quality. These undesirable results are also referred to as sustainability indicators. The organization of Chapter 5 aligns with the six sustainability indicators specified in the GSP regulations. Chapter 5 describes the current and historical groundwater conditions in the SLO Basin, including a series of maps showing groundwater flow direction and groundwater level contours over several decades, allowing for the visualization of changes in groundwater elevation over time. These maps document that areas within City limits have not experienced significant reductions in groundwater elevation, and thus groundwater storage, over the examined period of time. On the contrary, areas within the Edna Valley area of the SLO Basin have experienced significant, continual declines in groundwater elevation over time. The stability in groundwater elevation within City limits can be attributed to the City's increased surface water use for potable needs, a reduction in total water demand, and the substantial reduction in groundwater use since the early 1990s. On the contrary, the Edna Valley area's declining water levels can be largely attributed to increases in agricultural operations over time. Packet Page47W 1183 Item 6 Explanation W''Le ,,iiju-1 Gh v Spring IF 1 �v �-aam-zn feel r t �y ryy q-zoM -local to rel CIr Baer NMajor R—d Pr.avea roi: CNnge In Grn d—ter Ei—tion A'i.. sw_.r.anir.wwrr SRNL SAD YALIE Ep4N OSp r • '11i""'" J Rg.. id Figure S- Changes in Groundwater Elevation from 1997 - 2011 sprIng — IE Spnpa 2 1 Just as pumping groundwater for domestic and agricultural uses can remove water from a groundwater basin, infiltration of rain, subsurface inflow from surrounding bedrock, and percolation of streamflow from local creeks can return water to the groundwater basin. This chapter qualitatively describes these, and other various groundwater recharge and discharge types within the SLO Basin. Following discussions related to the connection between groundwater and stream flows, the chapter addresses groundwater quality within the basin. While SGMA is not designed to resolve any specific groundwater contamination issues, it is important that the actions within a GSP not allow for the worsening or exacerbation of groundwater quality issues. Chapter 6: Water Budget Chapter 6 takes the description of water flowing in and out of a basin and attempts to quantify this flow volumetrically. The purpose of a "water budget" is to provide an accounting and assessment of the total annual volume of groundwater and surface water entering and leaving a basin. A water budget identifies and quantifies various components of the hydrologic cycle within a user -defined area, in this case the SLO Basin. Water circulates between the atmospheric system, land surface system, surface water bodies, and the groundwater system, as shown in Figure 6. Packet PaVe4T&f 1183 Item 6 Almosphere Ewapomanspiraiian Evaparawn kr Evaporation krlpaled A�itultur9 Slfaamibw W Preapdstion Recharge 8win Groundwaler Tamp lnjKtipn Waal Agicuhural Supply Well Walls' Mu ni a patllneustria l Ca d rad ft4er Supply Well Unconfined Aqueer Figure 6 — The Hydrologic Cycle. Source: Department of ' Water Resources (Water Budget BMP, 2016) This chapter of the GSP provides an accounting and assessment of the total annual volume of groundwater and surface water entering (inflow) and leaving (outflow) the SLO Basin for historical and current conditions, as well as future conditions with climate change and management actions. The current water budget developed for this chapter was prepared for the two subareas that cover the SLO Basin, the San Luis Valley subarea and the Edna Valley subarea, both individually and combined into a single water budget for the entire Basin. This water budget results in estimates of the preliminary sustainable yield and overdraft, or surplus, for both subareas and for the entire Basin which are outlined in Table 1 and Table 2 below. The water budget equation used within this chapter to account for available water is as follows: Inflow — Outf low = Change In Storage Table 1— Preliminary Sustainable Yield Estimate (Acre -Feet / Year) San Luis Valley Subarea 2,500 Edna Valley Subarea 3,300 Basin Total 5,800 Table 2 — Estimated Overdraft (Acre -Feet / Year) San Luis Valley Subarea -700* Edna Valley Subarea 1,100 Basin Total 400 *Surplus water available Packet PaVeMbf 1183 Item 6 Next Steps Through the first six GSP chapters, no major decisions have been made regarding long-term management of the SLO Basin. The first six chapters have largely served to define an effective governance structure, ensure all stakeholders are included in the GSP development process, and to compile data that will help to better understand local basin geology and groundwater conditions. Chapters 7 and 8, which are currently being drafted, set goals for where groundwater levels should be maintained in the SLO Basin and establish a groundwater monitoring network which will be used to track progress toward meeting these goals. These management goals will become the basis for defining what sustainability looks like in the SLO Basin. In 2021, Chapters 9 and 10 will be drafted, which identify the projects and management actions that will need to be undertaken in order for the basin to achieve sustainability by 2042. These projects and management actions may consist of strategies such as reductions in groundwater pumping, conservation, irrigation efficiencies, agricultural irrigation reductions, and water supply augmentation efforts. Figure 7 below summarizes the five major steps to the GSP development process and where we are currently in the drafting process. 5 Steps to Sustainable Groundwater in the SLO Basin 2019 2020 Ak 2021 JAN. 70.72 WE ARE HERE Figure 7 — GSP Development Steps As Chapter 9 is drafted, augmentation projects will look at all locally available water to potentially supplement supplies in the Edna Valley area. It is likely that delivery of a portion of the City's recycled water supplies will be examined as one of many potential projects and management strategies. When examining augmentation projects and other management actions, it is important to remember that while SGMA goals are not required to be met until 2042, they will need to be perpetually maintained after 2042. Thus, the City must ensure that any participation in management actions, does not prohibit the City from meeting future in -City water demand, even after 2042. Packet Page4Mf 1183 Item 6 ENVIRONMENTAL REVIEW The California Environmental Quality Act (CEQA) does not apply to the recommended action, because the action does not constitute a "Project" under CEQA Guidelines Sec. 15378. FISCAL IMPACTS Budgeted: NA Budget Year: NA Funding Identified: NA There is no fiscal impact with the actions before Council. Staff time dedicated to the SGMA effort are incorporated in the annual budget appropriations. ALTERNATIVES Request staff return to the City Council, acting as the GSA, with additional information regarding GSP development. Attachments: a - Draft Communication and Engagement Plan b - Draft Data Management Plan c - COUNCIL READING FILE - Draft GSP Chapters 1-2 d - COUNCIL READING FILE - Draft GSP Chapters 3-4 e - COUNCIL READING FILE - Draft GSP Chapter 5 f - COUNCIL READING FILE - Draft GSP Chapter 6 g - COUNCIL READING FILE - City and County GSP MOA Packet Page4Mf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin —June 5, DRAFT Communication and Engagement Plan for Groundwater Sustainability Plan Development in the San Luis Obispo Valley Groundwater Basin Prepared for San Luis Obispo County June 5, 2019 0 Packet PaMf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin —June 5, 2019 Table of Contents 1. 2. 3. 4. 5. 6. 7. W Introduction to the San Luis Obispo Valley Basin Goals and Desired Outcomes GSP Participants and the Decision -Making Process Stakeholder Groups Stakeholder Survey Venues and Tools: Opportunities for Engi Evaluation and Assessment Appendices I 1 2 5 6 10 12 13 16 17 Packet Fage4g*f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin —June 5, 2019 The Sustainable Groundwater Management Act (SGMA) requires local governments and water agencies in California's high- and medium -priority groundwater basins, as defined by the California Department of Water Resources (DWR), to form Groundwater Sustainability Agencies (GSAs) and operate under a Groundwater Sustainability Plan (GSP) by the year 2022. Basins subject to critical conditions of overdraft must begin to manage groundwater under a GSP sooner — by January 31, 2020. This Communication and Engagement Plan (C&E Plan) describes the planned activities for engaging interested parties in SGMA implementation efforts in the San Luis Obispo Valley Basin. It is designed to meet the stakeholder engagement requirements of SGMA and the GSP Regulations. The ultimate purpose of the document is to facilitate effective communication and engagement with the multiple and varied stakeholders in the San Luis Obispo Valley Basin. Structure of this UE Plan DWR defines the purpose of its Stakeholder Communication and Engagement Guidance Document (C&E Guidance Document) to: • Demonstrate how a GSA can effectively communicate and engage with multiple and varied stakeholders • Identify the methods and tools to support communication and engagement • Identify how a GSA can conduct meaningful engagement to develop a GSP The C&E Guidance Document describes DWR's seven -step process for communication and engagement: 1. Set Goals and Desired Outcomes 2. Identify Your Stakeholders *=. 3. Stakeholder Survey and Mapping 4. Messages and Talking Points S. Venues for Engaging 6. Implementation Timeline 7. Evaluation and Assessment This C&E Plan is organized to follow the steps suggested above and shown in Figure 1. Figure 1. Engagement Steps from DWR GSP Stakeholder and Engagement Guidance Document G 0 ir' 0 III Set Goals and Identify Stakeholder Messages Venuesfor Implementation Evaluation Desired Your Survey and and Talking Engaging Timeline and Outcomes Stakeholders Mapping Points Assessment Describe the Develop a broad Conduct Del7ne the key Identify Create timeline At certain points situation at high Ustofindividuals, stakeholder messagesyou opportunities to inform the on the timeline evel—set clear goals groups, and survey to develop need to effectively (venues and process and evaluate if (and to and objectives, organizations who a "Lay of the convey to your methods) to highlight when to what degree) you identify overriding need to engage in Land"document various engage engage with are meeting the concerns the process stakeholders stakeholders stakeholders C&Egoals 1 Packet IRaqw-44f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, 2019 1. Introduction to the San Luis Obispo Valley Basin The San Luis Obispo Valley Basin (Groundwater Basin 3-0091) is situated in the San Luis and Edna Valleys in central to southwest San Luis Obispo County. The basin overlies an area of approximately 12,700 acres and is part of the Central Coast Watershed. It is bound on the northeast by the Santa Lucia Range, on the southwest by the San Luis Range, and on all other sides by contact with impermeable Miocene and Franciscan Group rocks. A rise in bedrock south of the San Luis Obispo Airport has created two separate subsurface drainage systems known as the San Luis Valley subbasin and the Edna Valley subbasin. The Edna Valley subbasin covers approximately 4,700 acres and is entirely within the unincorporated San Luis Obispo County (County). The San Luis Valley subbasin spans approximately 8,000 acres and includes both the unincorporated county and city of San Luis Obispo (City). • City of San Luis Obispo. The City of San Luis Obispo is located near the intersection of Highway 101 and Hwy 1. A portion of the City is located within the basin. The City's land uses consist primarily of commercial and residential areas. • San Luis Obispo County. San Luis Obispo County is located in the southern region of California between approximately San Miguel and Santa Maria. The entire basin is located within the County. The County's land uses consist of commercial, agricultural, residential, and undeveloped lands. The primary sources of water supply for uses in the basin include groundwater from the San Luis Obispo Valley Basin and surface water from the Whale Rock Reservoir, Salinas Reservoir, the Nacimiento Water Project, and recycled water through the City's Water Recycling Program.2 Water users in the basin include municipalities, communities, rural domestic residences, and industrial, environmental, and agricultural users. The major water purveyors are the Edna Valley Growers Mutual Water Company, Varian Ranch Mutual Water Company, Edna Ranch Mutual Water Company, and Golden State Water Company. Figure 2 shows the location of the San Luis Obispo Valley Basin and the GSA boundaries. 1 As identified and delineated in California Department of Water Resources Bulletin 118 https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118 2 https://www.sIocity.org/government/department-directory/utilities-department/water/water-sources/recycled- water 2 Packet IRaqw-f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 Figure 2. San Luis Obispo Valley Basin Groundwater Sustainability Agency Boundary San Luis Obispo Valley Basin Groundwater Sustainability Agencies Boundaries and Related Entities ' - DWR - Bulletin 118 ,. 4� San t tis Obispo Val" ff,� ! r :.. Graardwater Basin Boundary a,**' ._� ,? Department if Water } J.FW ` Other Bulletin 118 Gramdwater Basins City of San Luis . Obispo Service Area County of San Luis Obispo Service Area GSAs clb ar aoan San Luis Obispo l�un f d ObiCityspo GSA CSan overage Poverage rMi Area San Ws Obit Valley if Basin - County of San r.. f Luis Obispo GSA 1t r✓ _ CoverageArea Other Potential Pwtners �}^ .J� 1 F' d 101 Him Ranch Blroa YerT Ikutval Waler Company -Earl _�.,a r „L,. Edna lunch Mutual � Water Cain East Service Area J P �r - C 9eawe7silutiuer w�� reenr Golden State Weser J' Company - Edna Service Area F VaAan 3:anoh wvhual WM.r CampanY Marian Ranch Mutual Water Company 1- Service Area a Edna Valk y Growers Muhral Water Company Service Area i d i oe 4 7 a .p I 7 Packet IFaVMbf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 This page intentionally left blank. Packet PaVeMZbf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 2. Goals and Desired Outcomes The goal of this C&E Plan is to describe the planned activities for engaging interested parties in SGMA implementation efforts in the San Luis Obispo Valley Basin and to provide opportunities for interested parties to participate in GSP development. This plan serves as a roadmap to support achieving the desired outcomes identified below. • Educate the public about the importance of the GSP and the value of their input. Stakeholder input is a critical part of the GSP development process. Basin stakeholders define the values of the local community and priorities for groundwater management. This valuable input identifies the unique concerns of the stakeholders and guides decision -making and development of projects and management actions. The C&E Plan is designed to encourage stakeholder participation and to disseminate information about GSP development. • Engage a diverse group of stakeholders. The C&E Plan is developed with thoughtful consideration about how to engage the diverse array of stakeholders in the basin. One size does not fit all when it comes to stakeholder engagement. The C&E Plan outlines multiple venues for communication with varied audiences. • Make stakeholder participation easy and accessible. One way to increase engagement is to make participation easy for the stakeholders. The opportunities for stakeholders to engage in GSP development should be clear and easily accessible. The C&E Plan provides methods to make engagement easy for stakeholders. • Allow interested parties the opportunity to provide meaningful input. Aligning the engagement schedule with the GSP development schedule allows stakeholders to engage at key decision points in the GSP development process. Public meetings will inform interested parties about what decisions need to be made, provide relevant technical information, and request feedback. • Provide a roadmap for GSA leadership. The C&E Plan provides a clear roadmap and schedule for GSA leaders to follow, keeping engagement efforts consistent among stakeholders and on track throughout the duration of the project. The goal and desired outcomes listed above are the drivers for this planning document. They inform and shape the remainder of this C&E Plan. 5 Packet Fage4Mf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 I GSP Participants and the Decision -Making Process Everyone in the basin has a role to play in GSP development. Generally, participants fall into one of the following groups. • GSA Leadership • Technical Experts • Interested Parties Each of these groups provide a unique contribution to the GSP. GSA Leadership To comply with SGMA, two GSAs were formed to manage the groundwater resources of the San Luis Obispo Valley Basin in a sustainable manner as directed under a GSP that must be prepared by 2022 and implemented for the next 40 years • City of San Luis Obispo Groundwater Sustainability Agency • San Luis Obispo Valley Basin - County of San Luis Obispo Groundwater Sustainability Agency In January 2018, the City and the County entered into a Memorandum of Agreement (MOA) with the Edna Valley Growers Mutual Water Company, Varian Ranch Mutual Water Company, Edna Ranch Mutual Water Company, and Golden State Water Company to prepare a single GSP for the San Luis Obispo Valley Basin, establishing the Groundwater Sustainability Commission (GSC or Commission). The GSC serves as an advisory committee to the San Luis Obispo City Council and County of San Luis Obispo Board of Supervisors. The GSC has five members as shown in Table 1. Table 1. Commission Membership San Luis Obispo Valley Groundwater Sustainability Commission Members • One member representing the City • One member representing the County • One member representing Edna Valley Growers Mutual Water Company • One member collectively representing Varian Ranch Mutual Water Company and Edna Ranch Mutual Water Company • One member representing Golden State Water Company All meetings of the Commission are open to the public and interested parties are encouraged to attend. The Commission will make recommendations to the City Council and County Board of Supervisors regarding GSP development (e.g., recommendation to adopt). A public Notice of Intent to adopt the GSP and a public hearing will be held prior to adoption of the GSP. The final decision -making power to adopt the GSP will be executed separately by the City Council and County Board of Supervisors. 6 Packet Fage48171bf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 Technical Experts Technical experts are there to provide subject matter expertise on highly complex issues about the basin and surrounding basins and to inform the Commission and interested parties about the benefits and consequences of potential projects and management actions identified in GSP development. Technical experts may include outside consultants or staff of agencies that are signatories to the MOA. Section 3.2 of the MOA outlines how the City and County will retain consultant services. Interested Parties Interested parties consist of beneficial users of groundwater, stakeholders, and anyone affected/impacted by groundwater in and around basin. The interested parties may represent environmental interests, Native American tribes, agricultural interests, urban groundwater users, etc. GSA Leadership and Technical Experts provide information to interested parties through the engagement venues and tools described in this plan. The interested parties provide input regarding the priorities and values of the community and the likelihood of the success of proposed project concepts and the hurdles that must be overcome to achieve groundwater sustainability. Interested parties may also include agencies, such as the U.S. Department of Fish and Wildlife, with an interest in sustainable groundwater management in the basin. Interested parties can participate in the GSP development process by attending public meetings, commenting on draft documents, and participating in workshops. More information on interested parties is included in Section 4. Stakeholder Groups. GSP Chapter Review Process The San Luis Obispo Valley Basin GSAs formulated a process for reviewing draft GSP chapters, as illustrated in Figure 3. GSA leadership, technical experts, and interested parties have an opportunity to provide feedback on each chapter of the GSP at varying stages of the review process. The individual chapters will be prepared by the consulting team with input from GSA staff. After the draft chapters have been approved by the Commission they will be posted on the Portal to begin a minimum 30-day comment period. Specific dates will be provided for each draft document to allow for adequate review. Public comments will be submitted through the Portal and all comments received will be available for review. The comments will be reviewed by the technical experts and be considered for inclusion in the draft GSP. 7 Packet Fage4Mf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin —June 5, 2019 Figure 3. GSP Chapter Review Process Technical Specialist .............................................................................................................................................................................................................. Consultant X X .............................................................................................. I ...... I .................................................. ,..................................... I ........ GSA Staff X ........................................................................................................................................................................................................ GSA Leadership GSC (the Commission) X ....................................................................................................................................................................................................... Interest Parties X ............................................................................................................................................................................................................. GSA GSP Review Process r r Comments collected during public review of draft chapters will be considered when revising the chapters for the Draft GSP. After the draft GSP has been approved by the Commission it will be posted on the Portal to begin an additional minimum 30-day comment period. The roles of the GSP participants in preparation of the Final Draft GSP will follow the steps shown in Figure 4. Figure 4. GSP Review Process from reviewed chapters 8 Packet PaMf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 GSP Adoption Process Once the GSP has been finalized, the Commission will make a recommendation to the GSAs to adopt the GSP. The City of San Luis Obispo City Council and San Luis Obispo County Board of Supervisors will then consider adoption of the GSP. The GSP participants with responsibilities in this phase are shown in Figure 5. Figure S. GSP Adoption Process J 1 TA / It 1 1 0] Packet PWWL490f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 4. Stakeholder Groups Pursuant to California Water Code sections 10723.8 and 10723.2, the San Luis Obispo Valley Basin GSAs will consider throughout the project the interests of all beneficial uses and users of groundwater, as well as those that are responsible for implementing the actions developed within the basin's GSP. The San Luis Obispo Valley Basin GSAs are committed to an open public review and feedback process, including active and open discussions with all interested parties during the GSP development process. AppendixA includes the initial list of interested parties submitted to the California Department of Water Resources at the time of the GSA's formation. The list includes parties grouped by the categories below. • Agencies • Water corporations regulated by PUC or a Mutual Water Company • Agricultural users • Domestic well owners • Municipal well operators • Public water systems • Local land use planning agencies • Environmental users of groundwater • Surface water users • Federal government • California Native American tribes • Disadvantaged Communities % Stakeholder Group Identification The stakeholder list provided in AppendixA was used to form the Basin's initial interested parties list. The interested parties list was expanded by adding information collected via the SGMA interest e-mail list hosted on the County's website.3 The SGMA interest e-mail list has been online for more than one year and over 280 parties have indicated interest in being added to the Basin's mailing list. Once signed up for the interest list, parties are contacted via email when events related to GSP development are scheduled for the San Luis Obispo Valley Basin. The interested parties list will continue to expand as people answer the stakeholder survey (Section 5) and are encouraged to sign up for communications via the Groundwater Communication Portal described below. Groundwater Communication Portal A web -based outreach tool called the San Luis Obispo Valley Basin Groundwater Communication Portal (Portal) electronically notifies interested parties when the GSAs host events regarding groundwater management. The Portal is used to grow and maintain the interested parties list described above. Interested parties can add themselves to the interest list and access draft chapters for review at any time by registering for portal access at [to be added once domain name has been purchased]. s https://www.slocounty.ca.gov/Departments/Public-Works/Committees-Programs/Sustainable-Groundwater- Management-Act-(SGMA)/San-Luis-Obispo-Valley-Groundwater-Basin.aspx 10 Packet FaVe4Sf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 The Portal will track outreach engagements such as Commission meetings and communications with individuals or groups of stakeholders involved in the development of the GSP and store the information in a database for GSA retrieval. The database will include meeting dates, locations, times, and documents such as meeting agendas. A description of the Portal and its functions is provided in Appendix B. 11 Packet W2)f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 5. Stakeholder Survey DWR created a stakeholder survey template hosted at the Communication and Engagement Digital Toolkit' webpage. The survey is designed to learn about stakeholder interests, issues, and challenges. The survey may include the following questions: • Are you familiar with SGMA regulations? • Are you currently engaged in activity or discussions regarding groundwater management in this region? • Do you own or manage land in this region? • Do you manage water resources? If yes, what is your role? • What is your primary interest in land or water resources management? • Do you have concerns about groundwater management? If so, what are they? • Do you have recommendations regarding groundwater management? If so, what are they? • What else do you want us to know? • Who else should we listen to? The survey has been customized for San Luis Obispo Valley Basin GSP development and is included as Appendix C. The survey is scheduled to be distributed to interested parties in Summer 2019. The results of the survey will be used to inform this plan and will be included in the Final C&E Plan submitted with the Final GSP. ' https://water.ca.gov/Programs/Groundwater-Management/Assistance-and-Engagement 12 Packet ftqw-f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 6. Venues and Tools: Opportunities for Engagement The San Luis Obispo Valley GSAs aim to encourage stakeholders with diverse social, cultural, and economic backgrounds to be actively involved in the GSP development. To achieve this goal, focused engagement and thoughtfully selected venues and tools should be employed. Focused Engagement The initial list of interested parties that was imported into the Portal from the County's SGMA email interest list included 290 entries. To support the diversity of elements and ensure we engage with potentially underrepresented communities on the list, the groups below will be given focused attention when choosing venues and tools for engagement. Disadvantaged Communities. The City is recognized as a Disadvantaged Community (DAC).s Meetings will be held in proximity to this area to allow easy access for interested parties. Information about GSP development and meeting dates/times will be posted in areas that the City has found to be successful in reaching underrepresented populations in previous outreach efforts. These areas include public events such as the Farmer's Market, City kiosks at City facilities such as the finance office where utility bills are paid, the parks and recreation department where after -school programs are coordinated, and other City facilities such as the Senior Citizens Center. Bilingual Residents. The GSAs will gather information regarding the languages spoken in the communities within the basin and provide translation services for the languages as appropriate per the Dymally-Alatorre Bilingual Service Act. • Tribal Governments. Per SGMA §10720.3(c), any federally recognized Indian tribe may voluntarily agree to participate in the planning, financing, and management of groundwater basins. There are no federally recognized Native American tribes within the geographic boundaries of the San Luis Obispo Valley Basin. However, the Northern Chumash Tribal Council community encompasses the County area. Therefore, the San Luis Obispo Valley GSAs will refer to DWR's Engagement with Tribal Governments Guidance Document and will contact the tribal representative to invite participation in GSP development. Stakeholder Workshops Stakeholder workshops are designed to create opportunities for stakeholders and other interested parties to provide meaningful input during GSP chapter development. The workshop schedule is aligned with the GSP development schedule (Appendix D) for this purpose. The workshops will be led by technical experts such as consultants or GSA staff. Workshop dates will vary based on when input is deemed most useful. Suggestions for optimizing the benefit of the workshops are listed below. • Choose workshop venues, dates, and times to maximize stakeholder participation. • Use the Portal to inform interested parties about workshops during GSP development. s Per DWR Disadvantaged Communities Mapping Tool at https://gis.water.ca.gov/app/dacs/; accessed May 28, 2019 13 Packet FaVe4Sbf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 • Announce the Portal at stakeholder workshops and encourage attendees to sign up. Groundwater Sustainability Commission Meetings Regular meetings of the Groundwater Sustainability Commission provide an opportunity for City and County staff, participating parties, and their consultants to present updates on the status of GSP development. Meetings are scheduled every three months (quarterly). See the GSP development schedule (Appendix D) for planned dates. An interested party may sign up on the emailing list using the Portal to receive updates on meeting dates and times. Meetings of the Groundwater Sustainability Commission are subject to the Brown Act and are open to the public. Public Notices and Hearings Meeting notices will be sent in advance of stakeholder workshops and Commission meetings. SGMA requires a publicly noticed hearing at three distinct points in GSP development: • At GSA formation §10723(b) — this process is complete • When a GSP is adopted or amended (§10728.4) • Before imposing or increasing fees Public Draft GSP Documents if I When draft GSP component documents (e.g., chapters) are released by the Commission, they will also be posted to the Portal and will be open for public comment. A comment form will be available on the Portal to submit comments on draft documents by chapter and section. These comments will be considered when revising the public draft documents and finalizing the Final Draft GSP chapters. Tools for Communication Initially, the GSAs anticipate producing the informational materials listed below. GSA Website The County has a webpage dedicated to SGMA implementation in the San Luis Obispo Valley Basin. Both the City and County websites point to this page' to share information on GSP development. The site will be supplemented by the Portal as discussed below. Groundwater Communication Portal (Portal) The GSAs will use the San Luis Obispo Valley Basin Portal as a tool to communicate with interested parties. The Portal will store interested party information and distribute e-mail invitations for events posted to the calendar, these events may include GSC meetings, workshops, and other outreach events. There are additional tools within the Portal that will be used to enhance communication. These tools include the following: • E-Blast. E-mails will be sent to interested parties for those who sign up for email notifications on the Portal using the a -blast tool. E-blasts will be effective for sending reminders of upcoming deadlines, such as the close of a survey or comment period. • Public Comment Form. During public comment periods, a form will be available on the Portal for interested parties to submit comments on draft GSP documents. The form allows comments ' https://www.slocounty.ca.gov/Departments/Public-Works/Committees-Programs/Sustainable-Groundwater- Management-Act-(SGMA)/San-Luis-Obispo-Valley-Groundwater-Basin.aspx 14 Packet IRaqw-4115)f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 by chapter and automatically stores the information for GSA review, reducing the risk of misplaced comments. Direct Mailing Communications about GSP development will be sent only in digital format. For those who don't have access online or prefer to receive direct postal mailings, the agenda and agenda packet will be mailed to those who request it. There may be times when a direct postal mailing is appropriate. The County sent a mailer in May 2019 to provide information about the next two Commission meetings. The mailer also includes a request form for the recipient to fill out and return to the County if he/she desires to receive notification of future events via postal mail. A copy of the mailer is provided as Appendix E. Outreach Materials Given previous outreach efforts within City limits, the City does not believe a direct mail piece would be effective in reaching community members or the DAC population. To reach these community members, the City plans to direct outreach efforts for SGMA meetings to online resources, public events such as a Farmer's Market, and with outreach at several City kiosks at City facilities including the finance office where utility bills are paid, the parks and recreation department where after -school programs are coordinated, and at other City facilities such as the Senior Citizens Center. FA Q A frequently asked questions (FAQ) document will be created and updated periodically throughout the GSP development. The FAQ will address questions about SGMA, San Luis Obispo Valley Basin GSAs, and the development of the GSP. Updates to the FAQ will be posted on the Portal and on the County and City websites. _%W it I 15 Packet Fagel5g&f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 7. Evaluation and Assessment The activities identified in this C&E Plan are designed to meet the goals and objectives identified in Section 2. Below, Table 3 lists tasks compiled from the contents of this C&E Plan. This is a working list that will be modified and updated as needed throughout GSP development. Table 3. Outreach Tasks C&E Plan Task Description Section 4 Launch Groundwater Link to Portal from existing website, announce URL at Communication Portal (GCP) Commission meeting, post future meetings to calendar, send invitations 5 Conduct Stakeholder Survey Modify DWR's stakeholder survey for this basin, collect stakeholder feedback via custom survey (Appendix C) 6 Assess need for translation Document the GSA determination of what constitutes a services substantial number of non-English speaking people per the Dymally-Alatorre Bilingual Service Act and the level to which translation services will be provided 6 Public Postings Post information about GSP development and meetings in public spaces within the City limits such as Farmer's Market and City facilities 6 Conduct Stakeholder Conduct stakeholder workshops per the GSP Workshops Development Schedule (Appendix D) 6 Public Notices Send meeting notices in advance of stakeholder meetings, including Commission meetings 6 Direct Mailing Send direct mail to land owners in unincorporated areas of the basin to announce GSP development and Commission meetings. Stakeholders who request it may have the agenda and agenda packet sent to them 6 Hold a public hearing for GSP Per SGMA § 10728.4, give 60-day notice and hold a adoption public hearing to adopt the final GSP before submitting to DWR 6 Include GCP URL on printed Educate public about where they can find information materials and updates related to groundwater management in the basin 6 Announce GCP at public Educate public about where they can find information meetings and updates related to groundwater management in the basin (GCP) Like the list above, this C&E Plan is a living document to be updated as needed throughout GSP development. Successful use and implementation of the task list and C&E Plan will indicate success. 16 Packet IRAVeF917bf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 8. Appendices Appendix A. Stakeholder lists submitted at time of GSA formations Appendix B. Groundwater Communication Portal (GCP) Appendix C. San Luis Obispo Valley Basin Stakeholder Survey Appendix D. GSP Development Schedule Appendix E. Postal Mailer: Groundwater Sustainability Plan Update Appendix F. References 17 Packet Pa68)f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, Appendix A. Stakeholder lists submitted at time of GSA formations Packet PaSgDf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin - May 29 GSA Formation Exhibit D: List of Beneficial Users InitiM List of Interested Parties within the San Luis 01)ispo Valley Basin Pursuant to the California Water Code Section 107232, the San Luis Obispo Valley Basin - County of San Luis Obispo Groundwater SustainabiI ity Agency, in coordination with other GSA With -in the San Luis Obispo Valley Groundwater Basin (Basin), will consider the interest of all beneficial uses and users, as well as those responsible for implementing a Groundwater Sustainability. Plan (GSP)_ The County of San Luis Obispo has developed a list of interested parties and will revise the listas needed throughout the development of the GSP. An initial list of stakeholders and interested parties within the proposed San Luis Obispo Valley Basin - County of San Luis Obispo GSAservice area, as defined in the water code, follows. AAy,en€� Countyof San Luis Obispo San Luis Obispo County Flood Control & Water Conservation District City of San Luis Obispo Coastal San Luis Resource Conservation District Water Corporations Regulated by PUC or Mutual Water Company: Edna Ranch Mutual WaterCompany - East Golden State Water Comparrf-Edna Varian Ranch Mutual Water Company Edna Valley Growers Mutual Water Company Maxwellton Mutual WVater Azricultural users: Individual agricultural landowners Farm Bureau Coastal San Luis Obispo Resource Conservation District UC Cooperative Extension USDA Conservation Service USDA Farm Service Agency G rower -Shipper Association SLO Wine Country Association Dorresdrwell owners: Individual rural residentialtsuburban landowners Tiffany Ranch CYConnerWay Municipal well operator s: Covered in other categories Pub li€ watersrtems: (per EHS records) 141 Suburban Road Water Supply 200 Suburban Road Water Supply Bea r Va II ey Wa ter Company 617/2U16 P age 11 Packet P99W 300f 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29 GSA Formation Exhibit D. List of Beneficial Users Initial List of Interested Parties within the San Luis Obispo Valley Basin Buttonwood Industrial Park -Inactive CB&I Constru€tors.In€ Chevron -Tank Farm Congregation Beth David Copeland S Investments East Airport Fiero Lane Water Company Edna Valley Vineyard Elks Lodge #322 Ernie Ball Inc Fero Lane Water Company Hidden Hills Mobilodge Higuera Apartments Holdgrafter & Associates Horizon Lane Water Supply Irish Hills J tyl Sims Water Supply Jespersen Ranch Laureate Water Company Madonna Inn Water Company Moll Properties Industrial Park Paragon Triangle Water Supply Poly Ranch R_ Howard Strabaugh Inc San Luis Business Park San Luis Sourdough- Inactive San Luis Water & Power SLO County Farm Bureau SLO Partners Sunset Drive -In Snack Bar Tank Farm Business Park Tank Farm Industrial Plaza Tiger Water Supply Toyota San Luis Obispo Va€hell Water System Wallace Water System Whitson Industrial Park Williams Water Company Edna Ranch West{not in basin) Local land use lap nninga=ncies: City of San Luis Obispo County of San Luis Obispo San Luis Obispo Council o` Government (SLO COG) 1517}2a16 P age 17 Packet P99W JUlof 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, GSA Formation Exhibit D. List of Beneficial Users India[ List of Interested Parties within the San Luis 01)ispo Valley Basin Environmental users oferoundwater:. Central Coast Salmon Enhancement The Nature Conservancy Surface water users. Individual agricultural Iandavvners City of San Luis Obispo Central Coast Salmon Enhancement Federal government: U.S_ Fish & Wildlife Caiifomia dativeArrerican tribes: Chumash — no specific water uses in area Qisadvantay,ed communities Covered under other categories 6/7/2,016 r' B ff= 13 Packet P99W 3jMf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, Appendix B. Groundwater Communication Portal (Portal) Packet P99W 3W3Df 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin —June 5, 2019 San Luis Obispo Valley Basin Groundwater Communication Portal (Portal) GEI Consultants developed a tool to help our clients with their SGMA outreach efforts. The tool, referred to as the [Portal Features Groundwater Communication Portal (Portal), can be I customized for any groundwater basin to track engagement • Maintain the GSAs' list of efforts. The GCP is a web -based tool where you can post interested parties events and automatically inform interested parties with the click of a button. Interested parties can register with the GCP to stay informed about events related to GSP development and register for individual events to receive updates. The GCP serves as a repository for all information about GSA meetings and interested parties. Storing all stakeholder engagement information in one place will be beneficial both for creating the communications section of the GSP and for continued tracking of outreach efforts moving forward to GSP 5-year updates and implementation. The Portal's administrative functions include report generation, so you can easily generate your list of interested parties or details about events (e.g., who was notified). Administrators may also add attachments to the events, including items such as meeting agendas, minutes, and sign -in sheets. 1 . a —ea--e + E C (D Mar. ire I ---- Welcome to the San Luis Obispo GCP • Allow interested parties to self - register • Post meeting details and documents • Automatically notify interested parties with the click of a button • Track who was notified and who replied to your invitation • View a calendar of events • Send e-mail blasts • Track outreach efforts with a communication log • Upload project documents and collect public comments camamms sustmnmle cmbha—,rmanagem,,t nctIs,hul reawres me mrepam ana implemenrmbn m crgrmexarer Slafamabtlity Plans 10SP1. Mgh arrtl McJlum p N grpunOwaler basins_ T. San Luis 0depo Gmumlmmer Basin (SL .l3) rs a blgli prlonry bas'n.lTerefpre, areaz wXbm me 9asn must. Inauraer a GBF by—, 11, 21Ig2 bermrlomeatngmrarmmrm acooperame ca-wm me prnpax mreaama aevenpnemdore-r ror me oecum«m open rer cammem portion ottlm Pa. Robles Basn in San ium Odspo—ty Sv �napigr 5-D IT For more lmmnatlm, please vl9l me Groundaala 5uslalrlabYlly Agenry mebslles aY 0bap[er ]-0 Glap[er e- oRasT •San Luis Dbls{m Valley Basle-Cpunlyd San LUIS q%po Appe A-DPNFT Illyor San l.uls W�spO . Appenaa8 DRAFT TTe Cpppma Comml—meets regulaMtp progress GSP acfrnlies. 0pppemNre OanmMee meetilgs are open to the. public. Pm Apwalle-DRAFT inlefesle[I in lbe management of groan&r in Ne San—Ol Bash aredIb alleM. M1ppend'uD�DRAFT Appenal%,-DRAFT The GmoMw Comlwni—Rmml lG )baOrs Cao,,a Cmnnepre nx hti arm—epeMs relaleh la AppunaR G-DRAFT impkrrentatipn in ple San Lms Obispo Basin. enaplerS F•roleats anb anagemam Mlbrls FaeCSMH Draft design for the San Luis Obispo Valley GCP Packet PROW 304Df 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 Appendix C. San Luis Obispo Valley Basin Stakeholder Survey (not included in this draft) Packet PRSW 34Wf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — June 5, 2019 Appendix D. GSP Development Schedule Packet P99W JMf 1183 Task 1 Project Adminstration ask 2 GSP Development nd Adoption 3 Coordination & munication �l•J l•� L•� l•J �,�) l•J ====flIEER w==== ir- w 10 w l•J l•1 l•J ►�r� ter/ 1 r� Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, Appendix E. Postal Mailer: Groundwater Sustainability Plan Update Packet P99W 3Mf 1183 Item 6 Draft Communication & Engagement Plan for San Luis Obispo Valley Groundwater Basin — May 29, A 11011 ROW r, Groundwater SIustainabiIity Plan Update The Groundwater Susta inability Cbmmisslon (GSC) for the San Luis Obispo Valley Groundwater Basin (SLO Basin) is preparing a Groundwater Sustainability Plan (GSP).The purpose of the GSP is to sustainably manage our groundwater resources and meet the requirements of the Sustainable Groundwater Management Act (SGMA). All interested stakeholders and members of the public are en€curaged to participate to help guidethe GSP developme nt process. Upcoming Meetings .......................................................... :o- MzInesdap, June 12 11 Mopsm Grounc6ater Sustainabiity Commission Meeting Ora* Cavnnxnxaffon and Ersp3gerrlenr Pion - rrx�ad'wakr Cawrnwimfiwrsi 271eb1d 1r;kryaredGr-otna1le&er-5rr*3oc VVkrer Vodd AUGUST 2019 n 17ate and Time: T6L1 Groundwater Sustainabiity Agency'V&rkshap The GSC Ixid a meeting on April 4, 2019 ra INirale and provide an awerwew cof the GSP process., The SL4&aslris p-3*wx3y is susiarrabilllyrhin gh rhea6vbpnxniof a GSP is described below. FUME I AND IXJGKWN PRASE 2 • :EFrdsrl ®UFMHAELE .rm.wraad aCSLLSEI'TIHC PtikSE EF�.rw Ro. • 3whrahl. rlrW lU Pk. Am dEb.. .s ►.,� w�.r€�,.�.: 9.tUMNAKIrF PHASE Orr 4.Q sl—"Ift am Gvd W—" @OOJKENfATlari SGWAr udYld.. Ci{sirtE5"nun s .J.dn..mw.rmh CON U k.d Rwi. cm ...m idr-�rRiebl D—bP— �rar.a.d R.ACM r,AarIuo-- }5xlllwr3020- pwzno- en:ra®mau- AaGrrSr= IFUNUM FSIMkk KaI AUGnlr= Jlne 12 meeting locaie�d at: SLO Cily.Cawnry Liahaary 995 palm Street Sen Lui3.Obispo, CA 93401 If you would like to receive email notification, please sign up For the SGMA Email List at: www.shscaFmb4�rca.gax; dabosisF At this website you can also Find out information about progress to -dote and all pasted agendas and meeling materials. PostalMai lingList RequestForm Son Luis CtkpoVr'a%E6.-jn-Cawnyof5anLuis G6ipoGrourdswarer5s.,srainad ryAgwicyr Yyao%vn& ro receiverree is q rrofd4toriola Tdprirkdrreetirg makri-A Please rear nlm gtise dented line and retumthis Nstcd Moat eg by posd malt pio-aseprasa$ ymrcoanraxr inibmlakm Fadavr. (phase List ldequeee Form to: 6=k aW ❑ Agenda DickTmu San Luis Obispo County Public Works Department ❑ Agenda Packet (a Feemary be applied) County Government Center, Pown 206 (inabdeF the ug?mdaj San Luis Obispo, CA 93408 Marne Email: dtmu@�=o-.sloxci.us I Phone: (805� 761-4473 Company Address City, State, Zip IN Packet P99W 3Mf 1183 Item 6 Appendix F. References Packet P99W 3'Mf 1183 Item 6 Stakeholder Communication and Engagement Guidance Document for Groundwater Sustainability Plan, Department of Water Resources, January 2018 Engagement with Tribal Governments Guidance Document for Sustainable Management of Groundwater, Department of Water Resources, June 2017 Packet P&qV 3'*f 1183 Item 6 DRAFT San Luis Obispo Valley Basin Data Management Plan Data Management System to Support Implementation of the Sustainable Groundwater Management Act Prepared for: County of San Luis Obispo GSA City of San Luis Obispo GSA Prepared by: GEI Consultants 2868 Prospect Park Drive, Suite 400 Sacramento, CA 95670 August 31, 2020 Packet P99W 3'Mf 1183 Item 6 Table of Contents Tableof Contents.....................................................................................................................................................1 1. Introduction.....................................................................................................................................2 1.1 SGMA DMS Requirements..................................................................................................2 2. Data Needs for SGMA....................................................................................................................3 3. Data Sources...................................................................................................................................6 4. Data Structure.................................................................................................................................7 5. Data Import......................................................................................................................................9 5.1 Data Compilation (STEP 1).................................................................................................9 5.2 Data Formatting and Review (STEP 2)...............................................................................9 5.3 Data Upload (STEP 3).......................................................................................................11 6. SGMA Data Viewer.......................................................................................................................12 7. DMS User Types...........................................................................................................................15 8. Data Retrieval................................................................................................................................16 Figures Figure 1. Groundwater Basins in San Luis Obispo County........................................................................................3 Figure 2. DWR's Sustainability Indicators and Metrics...............................................................................................4 Figure3. DMS Tables.................................................................................................................................................7 Figure 4. Template Import Process for Local Data...................................................................................................A Figure 5. Example Template (Well Pumping)...........................................................................................................11 Figure6. Design for Data Viewer.............................................................................................................................12 Figure 7. SLO County Exports Page Design............................................................................................................16 Tables Table 1. Monitoring data for the SGMA sustainability indicators................................................................................5 Table 2. Data Sources to Populate the DMS.............................................................................................................6 Table3. DMS Table Descriptions...............................................................................................................................8 Table4. Well Data Templates..................................................................................................................................10 Table5. Station Data Templates..............................................................................................................................10 Table 6. Independent Data Templates.....................................................................................................................10 Table7. Map Viewer Navigation...............................................................................................................................12 Table 8. Reference Data Not Stored in the DMS Database.....................................................................................13 Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 1 DRAFT Packet P99W 3'/f 1183 Item 6 1. Introduction The purpose of this Data Management Plan (DMP) is to describe the planned Data Management System (DMS) and the process for collection, review, and upload of data used to develop a Groundwater Sustainability Plan (GSP) for the San Luis Obispo Valley Groundwater Basin (SLO Basin). This document does not provide final specifications for a complete DMS. Rather, it describes the data needed to comply with SGMA, the method to be used for data collection, and the plan for DMS development. 1.1 SGMA DMS Requirements The Sustainable Groundwater Management Act (SGMA) requires development of a DMS. The DMS stores data relevant to development of a groundwater basin's GSP as defined by the GSP Regulations (California Code of Regulations, Title 23, Division 2, Chapter 1.5, Subchapter 2). The GSP Regulations give general guidelines for a DMS: § 352.6. Data Management System Each Agency shall develop and maintain a data management system that is capable of storing and reporting information relevant to the development or implementation of the [Groundwater Sustainability] Plan and monitoring of the basin. Note: Authority cited: Section 10733.2, Water Code. Reference: Sections 10727.2, 10728, 10728.2, and 10733.2, Water Code. § 352.4. Data and Reporting Standards (c) The following standards apply to wells: (3) Well information used to develop the basin setting shall be maintained in the Agency's data management system Note: Authority cited: Section 10733.2, Water Code. Reference: Sections 10727.2, 10727.6, and 10733.2, Water Code. § 354.40. Reporting Monitoring Data to the Department Monitoring data shall be stored in the data management system developed pursuant to Section 352.6. A copy of the monitoring data shall be included in the Annual Report and submitted electronically on forms provided by the Department. Note: Authority cited: Section 10733.2, Water Code. Reference: Sections 10728, 10728.2, 10733.2, and 10733.8, Water Code. To comply with SGMA, the SLO Basin DMS will store data that is relevant to development and implementation of the GSP as well as for monitoring and reporting purposes. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 2 DRAFT Packet P99W VMf 1183 Item 6 2. Data Needs for SGMA The SLO Basin is in San Luis Obispo County, California. The county spans multiple groundwater basins — 6 of which are engaged in SGMA activity. Each basin complying with SGMA is required to store data in a DMS. Rather than host several systems, a county -wide DMS will be implemented to support county data initiatives for SGMA and other non-SGMA data initiatives. Figure 1. Groundwater Basins in San Luis Obispo County' SGMA defines sustainable groundwater management as "the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results."2 Furthermore, SGMA outlines six undesirable results as follows:3 One or more of the following effects caused by groundwater conditions occurring throughout the basin: (1) Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. Overdraft during a period of drought is not sufficient to ' Source: California Department of Water Resources, SGMA Data Viewer, accessed August 14, 2020. 2 § 10721(v) 3 §10721(X) Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 3 DRAFT Packet P99W Mof 1183 Item 6 establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods. (2) Significant and unreasonable reduction of groundwater storage. (3) Significant and unreasonable seawater intrusion. (4) Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies. (S) Significant and unreasonable land subsidence that substantially interferes with surface land uses. (6) Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water. The presence or absence of the six undesirable results in a groundwater basin is determined by monitoring and reviewing data for six sustainability indicators (one for each undesirable result). A set of associated measurable objective and minimum threshold will be assigned for each indicator and will be included in the DMS. There are multiple metrics by which the sustainability indicators may be observed. The sustainability indicators and their respective metrics, as defined in the GSP Regulations and described by the California Department of Water Resources (DWR) in the Sustainable Management Criteria Best Management Practice (BMP) document,4 are shown in Figure 2. Figure 2. DWR's Sustainability Indicators and Metrics Sustainability Indicators Metric(s) Defined in GSP Regulations 4 & L(—%)- -, t I 11 4& Lowering Reduction Seawater Degraded Land Surface Water GW Levels of Storage Intrusion Quality Subsidence Depletion • Groundwater Elevation • Total Volume • Chloride concentration isocontour • Migration of Plumes • Number of supply wells • Volume • Location of isocontour • Rate and Extent of Land Subsidence • Volume or rate of surface water depletion a https://water.ca. 0,>7 v/LegacyFiles/groundwater/sgm/pdfs/BMP6Sustainable6Management_Criteria 2017-11-06.pdf. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 4 DRAFT Packet P99W 3Trabf 1183 Item 6 Table 1 describes the types of data that may possibly be monitored for each sustainability indicator. Sustainability indicators do not need to be tracked by every available monitoring type. Table 1. Monitoring data for the SGMA sustainability indicators Monitoring Data Types Water Quality 75 W o M Sustainability Indicator J o � ¢ �, � a o c C E — a> CU x o in U 0 0 +1 Lowering groundwater levels ✓ ✓ Reduction of storage ✓ ✓ Seawater intrusion ✓ ✓ ✓ Degraded quality ✓ ✓ ✓ ✓ Land subsidence VT ✓ ✓ ✓ ✓ Surface water depletion ✓ ✓ ✓ The DMS will accommodate data relevant to each sustainability indicator. The monitoring data types listed in Table 1 represent the various data sets required to populate the DMS for tracking sustainability indicators. However, there is additional data that is readily available and may be included in the DMS to assist with preparation of GSPs and to support annual reporting. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 5 DRAFT Packet P99W VI170f 1183 Item 6 3. Data Sources Table 2 illustrates the data sources that will be used to populate the DMS to support GSP development, sustainability indicator monitoring, and annual reporting. The data categories listed below inform the design of the DMS and support the data needs presented previously in Table 1. Table 2. Data Sources to Populate the DMS Data Category State and Federal Data Sources Local Data Well and Site Info Lithology Water Level Water Quality Subsidence Precipitation Land Use Surface Water (Diversions, Stream Gages) Pumping *Private parties and mutual water companies ✓ ✓ ✓ ✓ ID �Q �U xw -u =< C.-Q oU) BCD W in Up O � Ur Cn M Ooc �� 0 t :� E C6 C U C (n oU �cn Cz 0-0 U) a, E Q Q U C9 ✓ ✓ ✓ ✓ J E M 0 IL U) c N J a) is Sources a) a.) U � c a) a`.) CM Q co c � C6 :3 Q O U (' C O ✓ ✓ ✓ ✓ ✓ ✓ Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 6 DRAFT Packet P&qV 3212W 1183 Item 6 4. Data Structure The DMS will be comprised of a database plus an online web viewer. Data stored in the DMS will be separated by categories into tables. The tables shall contain columns and rows of data. Each field will hold a specific type of data, such as a number, text, or date. The planned DMS data tables are shown as Figure 3. The figure is color -coordinated to show the relationship between tables: • Main tables (Blue) — Each dataset will be associated with EITHER a well or a station (e.g., extensometer). These are the main tables and include point data with unique identification and locations. • Sub tables (Green) — Sub tables are related to the main tables and hold additional details about a well or site (e.g., correlation of a well with a water level measurement). Figure 3. DMS Tables Main Tables Sub Tables Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 7 DRAFT Packet P99W 3439Df 1183 Item 6 A brief description of the main and sub tables is provided as Table 3. Table 3. DMS Table Descriptions Table Description Main Tables Station Info Information about type of station (recharge site, diversion, gage, extensometer, GSP) and location information Well —Info General information about well, including well construction and screen information Sub Tables Diversion —Data Diversion volume measurements for a diversion site or managed recharge Gage_Data Measurements collected at river or stream gages Precipitation —Data Volumetric measurements collected at precipitation monitoring stations Subsidence —Data Measurements collected at subsidence monitoring stations (e.g., extensometer) Sustainability_Indicator Minimum Thresholds and Measurable Objectives set for monitoring network sites tracking Sustainable Management Criteria for SGMA compliance Water Quality Contains water quality data for wells or any other type of site Water Level Water level measurements for wells Well_Lithology Lithologic information at a well site (each well may have many lithologies at different depths) Well —Pumping Pumping or recharge measurements for wells Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 8 DRAFT Packet P&9V 3Mf 1183 Item 6 5. Data Import Importing data to the DMS consists of three steps, as shown on Figure 4 and listed below: 1. Data compilation 2. Data review and formatting 3. Upload data The DMS shall be designed to use this process to import data for all basins in San Luis Obispo County. The DMS development team will upload data to support the SLO Basin GSP. Data for other basins will be loaded by other teams' GSP efforts. Figure 4. Template Import Process for Local Data 1; D- STEP z; data �WITEP ata •ompilation Review/Formatting Gather desired ^10 Import NO data 10 errors? Input data to Import yes Data ready for spreadsheet populated visualization templates' templates AL to database Display errors for correction or other action QA/QC Process 'Templates are designed to normalize data entry 5.1 Data Compilation (STEP 1) Historical data must be gathered to populate the DMS. Select state and federal data (as provided earlier in Table 2) for the SLO Basin will be compiled by the GSAs and their consultant(s). Participating agencies and other stakeholders will compile local data and data for other basins in the County. 5.2 Data Formatting and Review (STEP 2) After the data is compiled, it shall be normalized by use of Microsoft Excel templates designed exclusively for the DMS. Each of the main and sub tables, described previously in Section 4, will have a template. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 9 DRAFT Packet P99W i2 lof 1183 Item 6 The tables below list and describe the templates planned for the DMS. There are three types of data templates: • Groundwater well data templates: for data associated with a well. Station data templates: for data associated with a station. A station is defined as any site, that isn't a groundwater well, tracking DMS data (e.g., extensometer). • Independent data templates: for data that is not associated with a single well or station. Table 4. Well Data Templates Template Description WELL INFO Well site information including construction and location WELL SCREEN Screened intervals associated with a well site WELL AQUIFER Aquifers associated with a well site WELL_LITHOLOGY Lithologic information at a well site (each well may have many lithologies at different depths) WELL WATER LEVEL Water level measurements taken at wells WELL PUMPING Pumping or recharge measurements for wells WELL —WATER —QUALITY Water quality data collected at well sites WELL_SUST_INDICATOR Minimum Thresholds, Measurable Objectives, and Interim Milestones set for wells (not stations) Table 5. Station Data Templates Template Description STATION —INFO Information about a non -well station (e.g., recharge site) and location information STATION —PRECIPITATION —DATA Volumetric measurements collected at stations such as precipitation monitoring sites STATION SUBSIDENCE DATA Measurements from subsidence stations STATION GAGE DATA Measurements collected at river and stream gages STATION —WATER —QUALITY Water quality data collected at non -well stations STATION —DIVERSION —DATA Diversion volume measurements for a diversion site or managed recharge STATION_SUST_INDICATOR Minimum Thresholds, Measurable Objectives, and Interim Milestones set for stations (not wells) Table 6. Independent Data Templates Template Description AGENCY Addresses and other identifying information about the source agencies for data in the system WATER YEAR Water year type (e.g., dry) DOCUMENT Document information including file type, name, and file path Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 10 DRAFT Packet P&qv 32f 1183 Item 6 The data templates will include rules restricting formatting and alphanumeric properties to provide quality assurance/quality control (QA/QC) and to prevent errors and duplication when importing. The templates include pop-up windows to describe the type of data that should be entered in each column. If a specific filter must be applied, then only values that meet the criteria will appear in a drop -down list. Figure 5 provides a screenshot of an example Excel template. Figure 5. Example Template (Well Pumping) When data is compiled it must also be reviewed for accuracy. The template restrictions described above provide one level of QA/QC. As a second level of QA/QC, the initial set of compiled historical data will be reviewed by the consulting team before it is migrated into the database. This review will be focused and limited in scope. It will include the following manual checks: • Identifying outliers that may have been introduced during the original data entry process • Identifying potential duplication of data • Removing or flagging questionable data • Visualizing data in various software platforms outside the DMS to further assess the quality of the data After the historical data is populated, future data will be reviewed by the County before it is fully imported to the DMS. 5.3 Data Upload (STEP 3) Once the data is formatted and reviewed it will be uploaded to the DMS and displayed with a visualization tool (described in the next section). When loading the data, an automated check will be run by the DMS to capture errors or duplicates, if any, and a response will be generated to indicate errors so they may be corrected. The upload templates will be available for download in the DMS interface to load future data. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 11 DRAFT Packet P99W 3Df 1183 Item 6 6. SGMA Data Viewer The DMS will include a user-friendly web viewer to display the SGMA data including the SGMA-specific sustainable management criteria (SMC) information such as representative monitoring sites, minimum thresholds, measurable objectives, and interim milestones. The DMS SGMA data will display both with a map view and a detail view. Clicking on a point on the map will reveal details of the selected well or feature. The viewer will generate a hydrograph for points with water level data, and time -series graphs for water quality and subsidence data. The visual design of the Data Viewer (with test data) is shown in Figure 6. Figure 6. Design for Data Viewer The types of data to be visualized on the map and available via the map's navigation menu are listed in Table 7. Table 7. Map Viewer Navigation Menu Navigation Description Groundwater Levels Water level data and associated wells with well completion reports. Groundwater Storage GSA groundwater storage monitoring network sites. Water Quality Water quality well and station data for greater than 100 constituents. Land Subsidence Subsidence data from extensometers and other stations plus InSAR data. Interconnected Surface Water Data related to the interconnected surface water sustainability indicator such as proximity wells, river and stream gages, precipitation stations, and more. Seawater Intrusion Sites tracking the SGMA seawater intrusion sustainability indicator. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 12 DRAFT Packet P99W 3Z4bf 1183 Item 6 Hydrogeologic Conceptual Model (HCM) Data useful for development of a hydrogeoglogic conceptual model of the basin including suitability of soil for recharge, geologic maps, and fault maps. Boundaries GSA and other relevant boundaries. There are two categories of data displayed on the map viewer: data stored in the DMS and reference data drawn directly from outside sources that is useful for groundwater management. All the data discussed in the previous sections, 3. Data Sources and 4. Data Structure, referred to data to be stored in the DMS database. Table 8 below displays a list of reference data that is available for display in the map viewer but is tied directly to an external source (such as CDEC), not to the data stored in the DMS. Table 8. Reference Data Not Stored in the DMS Database Menu Data Title Source Navigation Groundwater DWR Periodic . California Natural Resources Agency Open Data Platform Levels Groundwater https://data.cnra.ca.gov/dataset/periodic-groundwater-level- Measurements measurements • Water Data Library http://wdi.water.ca.gov/waterdatalibrary DWR Continuous . https://data.cnra.ca.gov/dataset/continuous-groundwater- Groundwater level -measurements Measurements . http://wdi.water.ca.gov/waterdatalibrary USGS Periodic . https://nwis.waterdata.usgs.gov/usa/nwis/gwievels Groundwater Measurements Seasonal Groundwater DWR Enterprise Water Management database (EWM), which Level Reports includes water level data previously stored in the DWR Water Data Library and CASGEM databases. Well Completion Reports . https://data.cnra.ca.gov/dataset/well-completion-reports • https://gis.water.ca.gov/arcgis/rest/services/Environment/i07 _WellCompletionReports/FeatureServer • https://gis.water.ca.gov/arcgis/rest/services/Environment/i07 WellCompletionReports/MapServer Water Quality Water Quality Portal . https://www.waterqualitydata.us/ (WQP) Land DWR Extensometers . https://data.cnra.ca.gov/dataset/wdl-ground-surface- Subsidence displacement USGS Extensometers . https://waterservices.usgs.gov/rest/Site-Test-Tool.html THE ALTAMIRA InSAR . Image Server: Dataset https://gis.water.ca.gov/arcgisimg/rest/services/SAR • Download @OpenData: https://data.cnra.ca.gov/dataset/tre- altamira-insar-subsidence NASA JPL InSAR . Image Server: Dataset https://gis.water.ca.gov/arcgisimg/rest/services/SAR • Download @OpenData: https://data.cnra.ca.gov/dataset/nasa-jpl-insar-subsidence Interconnected CDEC Stations . http://cdec.water.ca.gov/ Surface Water Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 13 DRAFT Packet P&qV 32%of 1183 Item 6 Menu Data Title Source Navigation Water Budget Statewide Crop Mapping . Feature Server: 2014 https://gis.water.ca.gov/arcgis/rest/services/Planning/CropM apping2014/FeatureServer • Map Server: https://gis.water.ca.gov/arcgis/rest/services/Planning/CropM apping2014/FeatureServer • Download and API @OpenData: https://data.cnra.ca.gov/dataset/crop-mapping-2014 Hydrogeologic UC Davis SAGBI . California Soil Resource Lab at UC Davis and UC-ANR. Conceptual Model Soil Survey Geographic . https://services.arcgis.com/P3ePLMYs2RVChkJx/ArcGIS/re Database st/services/DownloaderBasinsv2/FeatureServer/0 http://www.arcgis.com/home/item.html?id=c2b408ba5c0a4fe 1a79377906935c1a4 CGS Geologic Map - . Metadata: 750k Generalized https://maps.conservation.ca.gov/cgs/metadata/GDM_002_ G M C-750k—v2—metad ata. htm I • Webmap: https://maps.conservation.ca.gov/cgs/gmc/ • Service: http://spatialservices.conservation.ca.gov/arcgis/rest/service s/CGS/GeologicMapCA/MapServer/21 Quaternary Surficial . Project Website: Deposits http://www.conservation.ca.gov/cgs/fwgp/Pages/sr217.aspx • Metadata: https://maps.conservation.ca.gov/cgs/metadata/QSD_metad ata.html • Webmap: https://maps.conservation.ca.gov/cgs/qsd/ • Service: https://spatialservices.conservation.ca.gov/arcgis/rest/servic es/CGS/GeologicMapCA/MapServer Fault Activity Map of . Metadata: California https://maps.conservation.ca.gov/cgs/metadata/GDM-006— FAM_750k_v2_metadata. htm I • Webmap: https://maps.conservation.ca.gov/cgs/fam/ • Service: https://spatialservices.conservation.ca.gov/arcgis/rest/servic es/CGS/FaultActivityMapCA/MapServer Boundaries GSA Boundaries . DWR Bulletin-118 basin boundaries or as provided by client County Boundaries . https://data.cnra.ca.gov/dataset/california-counties Canals and Aqueducts . https://data.cnra.ca.gov/dataset/canals-and-aqueducts-local Disadvantaged https://data.cnra.ca.gov/dataset/census-block-group-2010 Communities Blocks Disadvantaged https://data.cnra.ca.gov/dataset/census-place-2016 Communities Places Disadvantaged . https://data.cnra.ca.gov/dataset/census-tract-2010 Communities Tracts Water Agencies https://data.cnra.ca.gov/dataset/water-districts CASGEM Groundwater . https://data.cnra.ca.gov/dataset/ca-bulletin-118- Basins Prioritization — groundwater -basins 2019 - Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 14 DRAFT Packet P&9V 32%of 1183 Item 6 7. DMS User Types All data stored in the DMS will be accessible by administrative users, based on user permissions. Some sensitive data, such as private well data, may require a higher level of permission to retrieve. These permissions will be determined by the client. Monitoring sites and their associated datasets are added to the DMS by managing entity administrators. In addition to user permissions, access to the monitoring datasets is controlled through assigning one of three options to the data type as follows: • Private data — Private data are monitoring datasets only available for viewing, depending on user type, by the entity's associated users in the DMS. • Shared data — Shared data are monitoring datasets available for viewing by all users in the DMS, except for public users. • Public data — Public data are monitoring datasets that are available publicly that can be viewed by all user types in the DMS; public datasets may also be published to other websites or DMSs as needed. Managing entity administrators can set and maintain data access options for each data type associated with their entity. Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 15 DRAFT Packet P99W 327bf 1183 Item 6 8. Data Retrieval Data may be retrieved in several ways: via the map viewer, by table, or by report type. • Map Viewer: The map viewer will be used to retrieve small amounts of data currently displayed on screen. • By Table: The Exports page will allow for export of entire DMS tables as comma - separated values (CSV) files. Figure 7 illustrates the design for the Exports page. • By Report Type: Reporting templates will be created to extract the specific group of data required for annual reporting to DWR. Figure 7. SLO County Exports Page Design Exports Data from each table can be exported from the DMS as CSV files. Use the links below to exportthe desired table(s). .'' WellData ®, Tables associated with wells can heexported using the lint¢below. Table Name Description Download File WILL INFO General well information and metadata(e.g, well identifiers, locations, depths, etc.) Download WELL_LITHOLOGY Lithology data associated with wells. Download WELL PUMPING Well pumpingdata. Download WELL _SUST_INDICATOR Well sustainabilityindicators. Download WELL_WATER_LEVEL Well water level data. Download WELL_WATER_QUALITY Well water quality data. Download Station Data Data associated with stations can be exported using the links below - Table Name Deacrption Download Fite STATION —INFO General station information and metadato (e.g. statdon identifier, location, type, etc.) Download STATION_DIVERSION_DATA Station diversion data. Download STATION_GAGE_DATA Station stream gage dato(e.g. flow, discharge). Download STATION —PRECIPITATION —DATA Monthly station precipitation data. Download STATION_ SUBSIDENCE DATA Station subsidence measurements. Download STATION_SUST_INDICATOR Station sustainability indicators. Download STATION_WATER_QUALITY Station water quality data. Download Data Management Plan GEI Consultants, Inc. San Luis Obispo Valley Basin DMS 16 DRAFT Packet P99W 328)f 1183 DRAFT Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin Technical Memorandum San Luis Obispo Valley Basin Groundwater Sustainability Plan Available for viewing in the June 21, 2021 Agenda Packet: June 16, 2021 Recommended the GSAs to receive and file for public comments: June 21, 2021 Available for public comments on www.slowaterbasin.com: June 22, 2021 Close of public comment period: July 22, 2021 Per the GSC's recommendation on June 21, 2021, Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin Technical Memorandum will be distributed to the City and County GSAs to receive and file. This draft document is now posted on the web portal: www.slowaterbasin.com for public comments. Comments from the public are being collected using a comment form available at www.slowaterbasin.com by clicking on "Submit Comment". If you require a paper form to submit by postal mail, please contact your local Groundwater Sustainability Agency (GSA). All comments submitted will also be posted online for viewing. Page 533 of 1183 Stillwater Sciences 895 Napa Ave., Suite B-4, Morro Bay, CA 93442 phone 805-570-7499 TECHNICAL MEMORANDUM DATE: October 19, 2020 TO: WSC and Cleath-Harris Geologists FROM: Aleksandra Wydzga and Ethan Bell (Stillwater Sciences) SUBJECT: Groundwater -Dependent Ecosystems in the San Luis Obispo Valley Groundwater Basin The purpose of this memo is to summarize known information about surface water hydrology relevant to Groundwater Dependent Ecosystems (GDEs) in the San Luis Obispo (SLO) Valley Groundwater Basin (Section 1), identify GDEs overlying and dependent upon the SLO Valley Groundwater Basin (Section 2), identify sustainable GDE indicators (Section 3) for the SLO Valley Groundwater Basin, and propose a hydrologic monitoring network to track these indicators over time (Section 4). GDEs are defined in California's Sustainable Groundwater Management Act (SGMA) as "ecological communities of species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface" (23 CCR § 351(m)). EXISTING SURFACE WATER HYDROLOGY 1.1 Overview of GDE Relevant Surface and Groundwater Hydrology The Basin is overlain by two watersheds: San Luis Obispo (SLO) and Pismo (Figure 1). Flows in SLO and Pismo Creeks can be divided into wet season flows, typically occurring from January to April, and dry season flows, typically from June to October. Short transitional periods occur between the wet and dry seasons. Wet season instream flows originate from a range of sources including precipitation -driven surface runoff events, water draining from surface depressions or wetlands, shallow subsurface flows (e.g., soil), and groundwater. Dry season instream flows, however, if present, are fed primarily by groundwater. As groundwater levels fall over the dry season, so do the corresponding instream flows. If groundwater elevations remain above instream water elevations, groundwater discharges into the stream and surface flows continue through the entire dry season (creating perennial conditions). If groundwater elevations fall below the streambed elevation, the stream can go dry. Streams that typically flow in the wet season and dry up in the dry season are termed intermittent. Due to climactic changes or groundwater pumping, over time streams can transition from historically perennial to intermittent conditions (Barlow and Leake 2012). Dry season flows supported by groundwater in the SLO and Pismo Creeks are critical for the survival of various special -status species, including but not limited to the federally threatened California red -legged frog (CRLF) (Rana draytonii) and Steelhead (Oncorhynchus mykiss). SLO Creek and Pismo Creek are underlain by numerous aquifers. These aquifers are connected to one another, and to surface waters, but the degree of connection varies spatially. Aquifers can include confined aquifers, unconfined aquifers, and perched aquifers (see Chapter 4 of the Draft Page 534 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Groundwater Sustainability Plan). Aquifers may be hydrologically linked with ponds, lakes, wetlands, and creeks. In the SLO Valley Groundwater Basin, few data exist to characterize the connection between surface water and groundwater. The SLO Valley Groundwater Basin is divided into two sub -basins: the SLO Valley sub -basin and the Edna Valley sub -basin. While the groundwater in these basins is hydraulically connected, a shallow subsurface bedrock divide between the two sub -basins partially isolates the deeper portions of the two aquifers (Appendix A). Groundwater in the Edna sub -basin flows both towards the SLO Valley sub -basin in the northwest portion of the basin and towards Price Canyon in the southwest portion of the basin. Groundwater flowing towards Price Canyon rises to the surface as it approaches the bedrock constriction of Price Canyon and the Edna fault system. A 1954 DWR map (Appendix B) best illustrates the groundwater flow from the Edna Valley sub - basin both towards SLO and into Price Canyon. As groundwater from the Edna sub -basin flows towards Price Canyon and rises to the surface, it creates a perennial reach of Pismo Creek that flows through Price Canyon and supports year-round critical habitat for threatened steelhead. 1.2 Losing and Gaining Reaches Streams are often subdivided into losing and gaining reaches to describe their connection to groundwater. In a losing reach water flows from the stream to the groundwater while in a gaining reach water flows from the groundwater into the stream. The connection between losing reaches to the regional aquifer may be unclear as water can be trapped in perched aquifers above the regional water table. Figure 1 shows the likely extent of known gaining and losing reaches in SLO and Pismo Creeks during typical late spring and dry season conditions. This map is compiled from various data sources, including a field survey of wet and dry reaches of SLO Creek (Bennett 2015), field surveys and flow measurements of Pismo Creek (Balance Hydrologics 2008), an instream flow study of Pismo Creek (Stillwater Sciences 2012), a regional instream flow assessment that included SLO and Pismo Creeks (Stillwater Sciences 2014), spring and summer low flow measurements in SLO and Pismo Creeks (2015-2018) (Creek Lands Conservation 2019), and consideration of the effects of local geologic features such as bedrock outcrops and faults, both of which can force deeper groundwater to the surface. The effect of faults and bedrock outcrops can be localized or extend for some distance downstream. Portions of the SLO and Pismo Creeks and their tributaries for which no data exist are left unhighlighted in Figure 1. In general, the extent of losing or gaining reaches can vary by water year type or pumping conditions. For example, East Corral de Piedra and West Corral de Piedra on the north- east side of the basin can be dry in the spring and summer during drier years but be flowing in wetter years (Creek Lands Conservation 2019). In contrast, gaining reaches shown on SLO Creek appear fairly consistent across water year types (Bennett 2015, Creek Lands Conservation 2019). Figure 1 is based on limited data sources and improved mapping of losing and gaining reaches is recommended (Section 4). Stillwater Sciences 2 Page 535 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Losin and Gainin Reaches g 9 Map Sources: Groundwater basin Intermittent stream Groundwater Basin: DWR Watershed boundary: Cal Water resno Watershed ❑ y Spring o 5 P g Faults: USGS Santa OF Springs: SWS & USGS 7.5 quad Cruz of / Gaining reach Fault location Roads, cities, rivers, � Losing reach — Certain waterbodies:LSRI 2016 Atascadero� Waterbody Uncertain o 0.11 is 3a1 .mer�r, Perennial stream 0 os i zMlies 5riltwatrr5ciences Santa Barbara Figure 1. Typical late spring and dry season losing and gaining reaches in the basin. Portions of the SLO and Pismo Creeks and their tributaries for which no data exist are left unhighlighted. Stillwater Sciences 3 Page 536 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs 1.3 Relevance to GDEs Depending on location and time of year, GDEs that overly the SLO Valley Groundwater Basin can be supported by a range of water sources including direct precipitation, surface runoff, shallow subsurface flow, and groundwater. Shallow subsurface flow can vary from short-term precipitation driven flow (e.g. macro -pores filled during a precipitation event that drain on the order of days to weeks) to flow that is directly connected to groundwater (e.g. groundwater discharge into streams during the dry season). In the wet season, GDEs overlying the SLO Groundwater Basin are supported by a wider range of surface and groundwater hydrological sources than in the dry season. In the dry season, the primary water source supporting the GDEs is groundwater, although in some reaches irrigation return flow may be present. Irrigation return flow can have surface water sources from outside the basin (e.g. City of SLO parcels) or local groundwater (e.g. Edna Valley). Groundwater supporting GDEs overlying the SLO Valley Groundwater Basin can originate outside of the groundwater basin or within the groundwater basin. Both our proposed our strategy to identify sustainable GDE indicators (Section 3) and our proposed monitoring network (Section 4) take advantage of and integrate these hydrologic realities to focus on the assessment and monitoring of GDEs in locations and during seasons that are reliant on groundwater originating in the SLO Groundwater Basin. 2 POTENTIAL GROUNDWATER DEPENDENT ECOSYSTEMS (GDES) AND ASSOCIATED FLORA AND FAUNA 2.1 Distribution of Potential GDEs Based on Best Available Vegetation and Wetland Data Groundwater dependent ecosystems (GDEs) are defined in California's Sustainable Groundwater Management Act (SGMA) as "ecological communities of species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface" (23 CCR § 351(m)). As described in The Nature Conservancy's guidance for GDE analysis (Rohde et al. 2018), a GDE's dependence on groundwater refers to reliance of GDE species and/or communities on groundwater for all or a portion of their water needs. The Department of Water Resources (DWR) compiled a statewide Natural Communities Commonly Associated with Groundwater database (DWR 2019). This database identifies potentially groundwater dependent ecosystems based on the best available vegetation and wetland data (Klausmeyer et al. 2018). DWR (2019) identifies potentially groundwater dependent wetland areas using National Wetland Inventory (NWI) wetland data (USFWS 2018). These data were evaluated and assessed to accurately capture wetland and riverine features. In the SLO Valley Groundwater Basin, the best available vegetation mapping dataset (FVEG) was from the California Fire and Resource Assessment Program Vegetation (California Department of Forestry and Fire Protection 2015). FVEG is a remotely sensed dataset that classifies vegetation to coarse types (i.e., the California Wildlife Habitat Relationship System). Given the limitations of this dataset to accurately capture and identify vegetation using a precise classification system, it was deemed inappropriate for use in determining potential GDEs in the SLO Groundwater Basin. Instead, a manual assessment of vegetation with potential groundwater dependence was conducted using National Agricultural Imagery Program 2018 color aerial imagery (NAIP 2018). Vegetation communities identified as potentially groundwater dependent included riparian trees and shrubs, and oak woodlands. Oak woodlands were considered potentially groundwater dependent, particularly coast live oak riparian woodlands, because coast live oak (Quercus agrifolia) is known to make use of groundwater at depths of up to 36 ft (see Steinberg 2002 and references cited therein). Some other species of California oak, particularly blue oak (Q. douglasii) are known to develop deeper roots Stillwater Sciences 4 Page 537 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs that can access deeper groundwater in fractured bedrock on hillslopes (up to 70 feet [Lewis and Burgy 1964]), however such landscape positions are substantially different from what would be expected for GDEs occurring within a recognized groundwater basin on valley bottom or floodplain alluvial deposits. Therefore, we rely on the species -specific rooting and groundwater depth data for coast live oak cited by Steinberg (2002). Potential vegetation and wetland GDEs were retained if the underlying depth to water in 2019 was inferred to be 30 feet or shallower based on the existing well network (Figure 2). Depth to groundwater was interpolated from seventeen wells for which groundwater level data was available in the spring of 2019 (WSC in progress). The depth to groundwater shown in Figure 2 is assumed to represent regional groundwater levels; however, the screening depth is known for only 6 of the 17 of the wells. Wells where the screened depth is unknown may be measuring groundwater levels for deeper aquifers that are unconnected to the shallow groundwater system, and thus groundwater deeper than 30 ft for a given well may not reflect the absence of shallow groundwater, but instead reflects the absence of data. To determine the hydraulic connectivity between potential perched aquifers to the regional aquifer, additional monitoring with nested piezometers could be utilized. For the purposes of differentiating between potential and unlikely GDEs, different assumptions were made for the SLO versus Edna Valley sub -basins in areas of no groundwater data. In the SLO sub -basin (underlying SLO Creek), it was assumed that the depth to regional groundwater was less than 30 feet because the limited available data indicate that groundwater in this sub - basin is generally relatively shallow. In the Edna Valley (underlying Pismo Creek), it was assumed that the depth to regional groundwater was more than 30 feet because the limited available data indicate that the groundwater in this sub -basin is generally deeper. One exception to this assumption was made on upper East Corral de Piedra where the conditions were assumed to be similar to those on upper West Corral de Piedra where early dry season wet conditions have been observed by Stillwater Sciences and Balance Hydrologics (2008). The 30-foot depth criterion is consistent with guidance provided by The Nature Conservancy (Rohde et al. 2019) for identifying GDEs. Stillwater Sciences Page 538 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Potential Groundwater Dependent Ecosystems Map Sources: . . Groundwater Basin: DWR ❑ Groundwater basin Watershed boundary: Cal Water Watershed boundary Wetland GDEs: DWR, CDFW & TNC Santa Fresno Depth to GW: GSI 2019 Cruz i76 Q Perennial stream Vegetation GDEs: Stillwater Sciences Roads, cities, rivers, waterbodies: Atascadero_ Intermittent stream ESRI 2016 Infrastructure y a 0.7s 15 i Qi-- i, Waterbody'I 0 os 1 1Miks Still. ate Sciences Santa B Figure 2. Potential Groundwater Dependent Ecosystems. Stillwater Sciences 6 Page 539 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs 2.2 Special -Status Species and Sensitive Natural Communities Associated with GDEs For the purposes of this memorandum, special -status species are defined as those: • listed, proposed, or under review as endangered or threatened under the federal Endangered Species Act (ESA) or the California Endangered Species Act (CESA); • designated by California Department of Fish and Wildlife (CDFW) as a Species of Special Concern; • designated by CDFW as Fully Protected under the California Fish and Game Code (Sections 3511, 4700, 5050, and 5515); • designated as rare under the California Native Plant Protection Act (CNPPA); and/or • included on CDFW's most recent Special Vascular Plants, Bryophytes, and Lichens List (CDFW 2020) with a California Rare Plant Rank (CRPR) of 1, 2, 3, or 4. In addition, sensitive natural communities are defined as: • vegetation communities identified as critically imperiled (S1), imperiled (S2), or vulnerable (S3) on the most recent California Sensitive Natural Communities List (CDFW 2020). To determine the terrestrial and aquatic special -status species that may utilize potential GDE units overlying the SLO Valley Groundwater Basin, Stillwater ecologists queried existing databases on regional and local occurrences and distributions of special -status species. Databases accessed include the California Natural Diversity Database (CNDDB) (CDFW 2019b), eBird (2019), and TNC freshwater species list (TNC 2019). Spatial database queries were centered on the potential GDEs plus a 1-mile buffer. Stillwater's ecologists reviewed the database query results and identified special -status species and sensitive natural communities with the potential to occur within and to be associated with the vegetation and aquatic communities in or immediately adjacent to the potential GDEs. Table 1 summarizes these special -status species and sensitive natural communities, describes their habitat preferences and potential dependence on GDEs, and identifies known nearby occurrences (Table 1). Wildlife species were evaluated for potential groundwater dependence using the Critical Species Lookbook (Rohde et al. 2019). The SLO Valley Groundwater Basin supports steelhead belonging to the South -Central California Coast Distinct Population Segment (DPS) which is federally listed as threatened. Within this DPS, the population of steelhead within the SLO Creek, and Pismo Creek portions of the groundwater basin have both been identified as Core 1 populations which means they have the highest priority for recovery actions, have a known ability or potential to support viable populations, and have the capacity to respond to recovery actions (NMFS 2013). One critical recovery action listed by the National Marine Fisheries Service (NMFS) includes the implementation of operating criteria to ensure instream flows allow for essential steelhead habitat functions (NMFS 2013). The SLO Valley Groundwater Basin was determined to have high ecological value because: (1) the known occurrence and presence of suitable habitat for several special -status species including the Core 1 population status of South -Central California Coast Steelhead DPS and several special -status plants and animals that are directly or indirectly dependent on groundwater (Table 1); and (2) the vulnerability of these species and their habitat to changes in groundwater levels (Rohde et al. 2018). Stillwater Sciences 7 Page 540 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Table 1. Special -status species and sensitive natural communities documented in the vicinity of the San Luis Obispo (SLO) Valley Groundwater Basin with a potential GDE association. Status' Common name Potential GDE Scientific name Federal/ to occur Query source association' Habitat association and occurrence State/CRPR Birds Nests in vertical bluffs or banks, usually adjacent to water (i.e., rivers, Bank swallow Some streams, ocean coasts, and reservoirs), where the soil consists of sand or Riparia —/ST/_ potential eBird Indirect sandy loam. This species relies on surface water that may be supported by groundwater (Rohde et al 2019). eBird occurrences in SLO Valley including Laguna Lake. Least bittern Some Freshwater and brackish marshes with dense aquatic or semiaquatic Ixobrychus exilis —/SSC/— potential eBird Direct vegetation interspersed with clumps of woody vegetation and open water. eBird occurrences in SLO Valley including Laguna Lake. Open shrubland or woodlands with short vegetation and and/or bare ground Loggerhead shrike —— /SSC/ Likely y CNDDB, Indirect for hunting; some tall shrubs, trees, fences, or power lines for perching; Lanius ludovicianus eBird typically nest in isolated trees or large shrubs. CNDDB occurrences in SLO Valley. Northern harrier Some Nests, forages, and roosts in wetlands or along rivers or lakes, but also in Circus hudsonius —/SSC/— potential eBird Indirect grasslands, meadows, or grain fields. eBird occurrences in SLO Valley including Laguna Lake. Peregrine falcon Some Wetlands, woodlands, cities, agricultural lands, and coastal area with cliffs Falco peregrinus —/SFP/_ potential eBird Indirect (and rarely broken -top, predominant trees) for nesting; often forages near water. eBird occurrences in SLO Valley including Laguna Lake. Freshwater emergent wetlands with dense stands of cattails (Typha spp.) and d Some bulrush (Schoenoplectus spp.) interspersed with areas of deep, open water; Aythya americana —/SSC/— potential eBird Direct forage and rest on large, deep bodies of water. Summer resident in southern California. eBird occurrences in SLO Valley including Laguna Lake along SLO Creek. Stillwater Sciences Page 541 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Common name Scientific name Status' Federal/ State/CRPR Potential to occur Query source GDE association' Habitat association and occurrence Feeds in grasslands and agriculture fields; nesting habitat components include open accessible water with dense tall emergent vegetation, a Tricolored blackbird CNDDB protected nesting substrate (including flooded or thorny vegetation), and a Agelaius tricolor —/ST/— Likely eBird Direct suitable nearby foraging space with adequate insect prey. Relies on groundwater dependent ecosystems for breeding and roosting (Rohde et al 2019). CNDDB occurrence in Edna Valley and eBird occurrence in SLO Valley including Laguna Lake, Pismo Creek, and Stenner Creek. White-tailed kite CNDDB Lowland grasslands and wetlands with open areas; nests in trees near open Elanus leucurus —/SFP/— Likely eBird Indirect foraging area. CNDDB and eBird occurrences in SLO Valley including Laguna Lake. Mammals Pallid bat Potential Roosts in rock crevices, tree hollows, mines, caves, and a variety of vacant Antrozous pallidas —/SSC/— Likely CNDDB Indirect and occupied buildings; feeds in a variety of open woodland habitats. CNDDB occurrence in SLO Valley. Amphibians and reptiles Breeds in still or slow -moving water with emergent and overhanging vegetation, including wetlands, wet meadows, ponds, lakes, and low - California red -legged FT/SSC/— gradient, slow moving stream reaches with permanent pools; uses adjacent frog Likely CNDDB Direct uplands for dispersal and summer retreat. Relies on surface water that may Rana draytonii be supported by groundwater (Rohde et al. 2019). Critical habitat is within the SLO watershed. CNDDB occurrences include SLO Creek and tributaries. Coast Range newt Chaparral, oak woodland, and grasslands. Relies on surface water that may Taricha torosa —/SSC/— Likely CNDDB Direct be supported by groundwater for breeding. CNDDB occurrences are in SLO Creek and Brizziolari Creek. Shallow tributaries and mainstems of perennial streams and rivers, typically Foothill yellow- associated with cobble or boulder substrate; occasionally found in isolated legged frog —/SE/— Unlikely CNDDB Direct pools, vegetated backwaters, and deep, shaded, spring -fed pools. All Rana boylii CNDDB occurrences are historical (1958) in Arroyo Grande Creek and population is possibly extirpated. Stillwater Sciences Page 542 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Common name Scientific name Status' Federal/ State/CRPR Potential to occur Query source GDE association' Habitat association and occurrence Northern California Chaparral, pine -oak woodlands, desert scrub, sandy washes, and stream legless lizard —/SSC/— Likely CNDDB Indirect terraces with sycamores, cottonwoods, or oaks. Occurs in moist warm loose Anniella pulchra soil with plant cover. CNDDB occurrences in Edna Valley. Ponds, lakes, rivers, streams, creeks, marshes, and irrigation ditches with Western pond turtle basking sites. Relies on surface water that may be supported by Emys marmorata —/SSC/— Likely CNDDB Direct groundwater. CNDDB occurrences include SLO and Edna Valley, as well as, Pismo Creek, Miossi Creek, Prefumo Creek, and Mainstem and East Fork of SLO Creek Fish Steelhead, South Rivers and streams with cold water, clean gravel of appropriate size for Central California spawning, and suitable rearing habitat; typically rear in fresh water for one DPS FT/—/— Likely CNDDB Direct or more years before migrating to the ocean. Suitable habitat present Oncorhynchus mykiss (migration, rearing); species known to occur in SLO and Pismo Creek and their tributaries i.e., West Corral de Piedra Creek). Plants and Sensitive Natural Communities San Luis Obispo Seeps, often with serpentine and sometimes gabbro soils or clay soils in sedge 44113.2 Likely CNDDB Direct closed -cone coniferous forest, chaparral, coastal prairie, coastal scrub, and Carex obispoensis valley and foothill grassland (CNPS 2020); all CNDDB observations are along Prefumo Creek and Froom Creek outside of the groundwater basin Congdon's tarplant Valley and foothill grassland (CNPS 2020); all CNDDB observations are Centromadia parryi —/—/1B.1 Likely CNDDB Direct within the SLO Creek watershed including around Laguna Lake and East subsp. congdonii Fork of SLO Creek Chorro Creek bog Serpentine seeps and drainages in chaparral, cismontane woodlands, coastal thistle FE/SE/1B.2 Likely CNDDB Direct scrub, and valley and foothill grassland (CNPS 2020); CNDDB observations Cirsium fontinale var. are limited to the SLO Creek watershed and are associated with seeps and obispoense springs, Clay and serpentine soils in chaparral, coastal prairie, meadows and seeps, Adobe sanicle —/CR/1B.1 Likely CNDDB Direct and valley and foothill grassland (CNPS 2020); multiple CNDDB Sanicula maritima occurrences in open grassy area of Laguna Lake Park, along Laguna Creek, and South Hills 10 Stillwater Sciences Page 543 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Common name Scientific name Status' Federal/ State/CRPR Potential to occur Query source GDE association' Habitat association and occurrence Saline clover Marshes and swamps, mesic and alkaline soils in valley and foothill Trifolium 44113.2 Likely CNDDB Direct grassland, and vernal pools (CNPS 2020); one CNDDB occurrence, located hydrophilum in Laguna Lake Park Coastal and Valley Dominated by perennial, emergent monocots including tules Freshwater Marsh —/52.1/— Likely CNDDB Direct (Schoenoplectus spp.) and cattails (Typha spp.). May form completely closed canopies (Holland 1986). CNDDB observations around Laguna Lake. Status codes: Federal FE = Federally listed endangered FT= Listed as threatened under the federal Endangered Species Act — No federal status State Rank SE = Listed as Endangered under the California Endangered Species Act ST = Listed as Threatened under the California Endangered Species Act SFP = CDFW Fully Protected species SSC = CDFW species of special concern CR = California State listed as rare S2.1 = CDFW imperiled and threatened species — No state status California Rare Plant Rank (CRPR) 1B = Plants rare, threatened, or endangered in California and elsewhere CRPR Threat Ranks 0.1 Seriously threatened in California (high degree/immediacy of threat) 0.2 Fairly threatened in California (moderate degree/immediacy of threat) — No CRPR status ' Groundwater Association Direct: Species directly dependent on groundwater for some or all of its water needs (e.g., cottonwood with roots in groundwater, juvenile steelhead in dry season) Indirect: Species dependent upon other species that rely on groundwater for some or all of their water needs (e.g., riparian birds) 11 Stillwater Sciences Page 544 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs 3 GDE EVALUATION AND SUSTAINABLE INDICATORS In Section 2 we identified potential GDEs distributed throughout the SLO Valley Groundwater Basin. In Section 3 we identify specific GDE types that are likely or have potential to occur in the SLO Valley Groundwater Basin. Each GDE type has a different requirement to sustainably function. For each GDE type we then identify sustainable GDE indicators and target values. Sustainable GDE indictors are metrics that can be monitored to determine if undesirable impacts are occurring. The target values are set based on the best available data for each GDE type. These values are determined by the needs of special -status species, sensitive natural communities, or keystone species associated with each GDE type. As more data becomes available, the indicator type or target value may be refined. Furthermore, sustainable GDE indicator target values may not be met due to management activities (e.g., pumping) or due to climate (e.g., extended drought conditions). Thus if sustainable indicator target values are not met, additional studies or assessments to determine the cause may be required. 3.1 GDE Types Eight distinct likely or uncertain types of GDEs have been identified in the SLO Valley Groundwater Basin. Likely GDE types include riverine (fast moving), riverine (slow moving), riparian, lacustrine, and wetland/marsh. Three uncertain GDE types include seasonal wetlands/wet meadows, springs and seeps, and oak woodlands. Seasonal wetlands are uncertain because their dependence of surface water versus groundwater is unknown and may be site specific. Spring and seeps are uncertain because they may be dependent on recharge from fractured bedrock in the surrounding hills rather than low SLO Valley Groundwater Basin water. Oak woodlands = r ! :i _ A are uncertain because groundwater elevation data from . _ -- areas they are present (e.g. the eastern Edna Valley) are unavailable. Additional studies for these GDE types are recommended in Section 3.2. The diversity of GDEs overlying the SLO Valley Groundwater Basin is due to the unique hydrogeomorphology of the basin, whereas the ' groundwater basin is oriented perpendicular to the general direction of surface water flow (Figure 2). A description of each GDE type along with associated special -status species, natural sensitive communities, and/or keystone species are listed in Table 2. Keystone species are defined as species that serve as indicators of GDEs sustainability. If the sustainable indicator target value is met for a GDE type with a keystone species, all habitats and species associated with that GDE type are assumed to be protected.:°,, While a complete list of special -status species with known occurrence or presence of suitable habitat in potential GDE units overlying or within 1 mile of the "A - SLO Valley Groundwater Basin are listed in Table 1, - loop only those species that have a direct association with GDEs are included in Table 2. Examples of species Stillwater Sciences 12 Page 545 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs omitted from Table 2 include species that are believed to have be extirpated from this area (e.g., foothill yellow -legged frog) or have an indirect association with GDEs (e.g., loggerhead shrike). Species that have an indirect association are assumed to be protected if the GDE indicators listed above are met. For example, the loggerhead shrike is known to occur within the SLO Valley Groundwater Basin. It lives in shrublands or woodlands with short vegetation and/or bare ground for hunting, uses tall shrubs and trees for perching, and typically nests in isolated trees. Some trees or shrubs used for perching or nesting may be part of a GDE; which is assumed to be protected if GDE indicators that are developed for each GDE type (Table 2) are met. Stillwater Sciences 13 Page 546 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Table 2. Summary of Groundwater Dependent Ecosystem (GDE) types known to occur in the San Luis Obispo (SLO) Valley Groundwater Basin. Associated special -status Key life stages GDE type GDE habitat description speciesA, sensitive natural primarily Sustainable GDE Monitoring Location and target value communities', or keystone dependent on indicator period s eciesc groundwater 1) Stenner Creek at Nipomo St = 0.85 cfs (late spring); Late spring (May- 0.33 cfs (dry season) (SWS June) and dry 2014) Steelhead South Central season (July —Oct) 2) SLO Creek at Marsh St = Riverine Fast moving, flowing California DPSc Juvenile steelhead Flow rate (cfs) 1.20 cfs (late spring); 0.90 (Fast moving) water Oncorhynchus mykiss cfs (late summer) (SWS 2014 Late spring (May— Pismo Creek at Railroad June) and dry crossing = 1.50 cfs (late season (July —Oct) spring)/; 0.50 cfs (dry season) (Stillwater 2016 California red -legged froggy Larval development and Slow moving or still Rana draytonii metamorphosis Riverine water; interspersed or Late spring (May — East Fork of SLO Creek at Larval (Slow interconnected with Coast Range newt development and Water depth (ft) June) and dry Jespersen Road = 2.3 ft moving) wetlands, marshes, or Taricha torosa metamorphosis season (July —Oct) grasslands Western pond turtle Foraging adults Emys marmorata and juveniles Least bittern All life stages Ixobrychus exilis Lacustrine/ Open water. Interspersed Laguna Lake Redhead Adults; potential Lacustrine or interconnected with wetlands marshes Aythya americans for limited resident E TBD TBD Connected tributaries, or grasslands breeding Target values TBD Tricolored blackbird All life stages Agelaius tricolor 14 Stillwater Sciences Page 547 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Associated special -status Key life stages GDE type GDE habitat description species`', sensitive natural primarily Sustainable GDE Monitoring Location and target value communities', or keystone dependent on indicator period' s eciesc groundwater Dominated by perennial, emergent monocots Wetland/ including tules Coastal and Valley Freshwater Tank Farm wetlands Marsh (Schoenoplectus spp.) and Marsh Adult plants TBD TBD cattails (Typha spp.). May Target value TBD form completely closed canopies Holland 1986 California Sycamore Dominated by mature Woodland; Fremont Depth to groundwater See Figure 3 and Table 3 for Riparian woody vegetation Cottonwood Forest and Adult trees (fl) and/or rate of TBD all proposed locations including cottonwoods, Woodland and/or Black groundwater sycamores, and willows Cottonwood Forest and elevation changeF Target values TBD Woodland An area that is inundated Adobe sanicle Sanicula by water seasonally (i.e., maritima Congdon's tarplant Seasonal present during the wetland/wet growing season but absent Centromadia parryi ssp. Adult plants TBD TBD TBD meadow by the end of the growing con donii, Saline clover Trifolium season in most years) (FGDC 2013) h dro hilum A location where water Chorro Creek bog thistle from the ground rises to Cirsium fontinale var. Springs and the surface, commonly obis oense Adult plants TBD TBD TBD SLO sedge seeps with saturated soil, standing, or flowing water Carex obispoensis ear -round. 15 Stillwater Sciences Page 548 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Associated special -status Key life stages GDE type GDE habitat description species`', sensitive natural primarily Sustainable GDE Monitoring Location and target value communities', or keystone dependent on indicator period' s eciesc groundwater Coast live oaks Depth to groundwater Oak Coast live oak riparian Quercus agrifolia; Adult trees (ft) and/or rate of TBD TBD woodlands woodlands G Pallid bat Antrozous pallidas groundwater elevation change A A list of special -status species with known occurrence or presence of suitable habitat in potential GDE units overlying the or within 1 mile of the SLO Valley Groundwater Basin are listed in Table 1. Of those species, only those species that are likely or have some potential to occur and that have a direct association with potential GDEs are listed in Table 2. a Sensitive natural communities as defined as vegetation communities that are critically imperiled, imperiled, or vulnerable on the most recent California Sensitive Natural Communities List (CDFW 2020) or by CNPS 2020. c Keystone species. n Monitoring is proposed only for those time periods for which each GDE type is anticipated to be primarily dependent upon groundwater originating in the SLO Valley groundwater Basin (see Section 4 for discussion). E TBD = To be determined F Depth to groundwater or the rate of groundwater elevation change in the dry season is anticipated to be the sustainable indicator for mature woody riparian vegetation and oak woodland based on research by Amlin, N. M., and S. B. Rood. 2002; Mahoney, J. M., and S. B. Rood. 1998; Rood, S. B., and J. M. Mahoney. 1990; Segelquist, C. A., M. L. Scott, and G. T. Auble. 1993; Shafroth, P. B., J. C. Stromberg, and D. T. Patten. 2002; and Vaghti, M. G., and S. E. Greco. 2007. G Pallid bats utilize oak savannahs, black oaks, oak grasslands, and open oak woodlands (Pierson and Rainey 2002). Oak savannahs are usually characterized by valley oak, blue oak, interior live oak, or coast live oak, with the specific composition dependent on latitude and elevation. Pallid bats typically roost in caves, crevices, bridges, buildings and occasionally tree hollows. 16 Stillwater Sciences Page 549 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs 3.2 Evaluation of Potential GDEs and GDE Types The potential GDEs and GDE types identified herein were based on the best available but limited groundwater data, wetland data and low -resolution vegetation data. These potential GDEs and GDE types require ground-truthing to determine the dominant vegetation types and quality, habitat types and quality, existing hydrologic conditions and their spatial extent to improve our understanding of their distribution and groundwater dependence. Ground-truthing should include reconnaissance level field -survey of a sub -set of accessible areas mapped as potential GDEs. At each site, field biologists could assess the following: (1) vegetation data (e.g., dominant vegetation types and plant species, indications of the proportion of live vs. senescent canopy, and vegetation density); (2) qualitative observations of hydrologic conditions (e.g. flowing or standing water); and, (3) habitat conditions for special -status or keystone species by comparing each species' habitat preferences (e.g., large trees, open water or herbaceous cover, etc.) to conditions present at the site. Based on this field data, GDE distribution, GDE type, and habitat for associated special -status species could be refined. Habitat assessments should be focused on federally or state threatened or endangered flora or fauna with direct groundwater association including the state threatened species Tricolored blackbird (Agelaius tricolor), the federally threatened California red -legged frog (R. draytonii), the federally threatened Steelhead trout (O. mykiss), and the federally endangered Chorro Creek bog thistle (Cirsium fontinale var. Obispoense). Furthermore, seven of the eight GDE types (Table 2) may require additional assessment/analysis to either determine the extent to which the GDE type is groundwater dependent, the timing of groundwater dependence, and/or to refine the sustainable GDE indicator or target values. To this extent the following are proposed for consideration: 2. Riverine (fast moving). Conduct an instream flow study of mainstem SLO and Stenner Creeks to identify flows required by juvenile steelhead in the late spring and summer/early fall dry season, as well as, an assessment of the quality of steelhead habitat in the East Fork of SLO Creek and Davenport Creek. Lacustrine. Conduct a study of Laguna Lake to determine the magnitude, timing and duration of the dependence of the Lake on groundwater originating from the SLO Valley Groundwater Basin (e.g. a surface -groundwater assessment/model). Based on the results of the study and associated special -status species habitat assessments, develop sustainable GDE indicator(s), timing of groundwater dependence, and indicator target values. Wetland/Marsh. Conduct an assessment of wetlands and marshes found within the SLO Valley Groundwater Basin that support special- Oak tree along East Corral de Piedra status species or sensitive natural communities; Creek determine the magnitude, timing and duration of their dependence on groundwater originating from the SLO Valley Groundwater Basin; and develop sustainable GDE indicator(s) and associated information. 17 Stillwater Sciences Page 550 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs 4. Riparian. Install groundwater monitoring wells at proposed locations (Table 3), collect and analyze data. Refine GDE indicator(s) and develop site specific target values for the depth to groundwater below the surface (ft) that will sustain the GDE at each location. 5. Seasonal wetlands. Conduct an assessment of seasonal wetlands and wet meadows found within the SLO Valley Groundwater Basin, especially those that support groundwater dependent special -status species including Adobe sanicle, Congdon's tarplant, and Saline clover. While these plants need soil saturation or inundation for seed germination, establishment and growth, the dependence on groundwater versus surface water is unknown and may be site specific. If seasonal wetlands primarly dependent on groundwater originating in the SLO Groundwater Basin are indentified, develop sustainable GDE indicator(s) and associated information. 6. Springs and seeps. Conduct an assessment of springs and seeps within the SLO Valley Groundwater Basin to identify their locations and to determine their dependence on groundwater originating from the SLO Valley Groundwater Basin. The study could include measurements of the magnitude and timing of flow rates and/or an isotopic analysis to identify water sources. It is anticipated that many springs and seeps will be dependent on recharge from fractured bedrock in the surrounding hills rather than SLO Valley Groundwater Basin water. Springs and seeps within the basin that are known to occur include but are not limited to the base of the South Hills, Irish Hills, and hills surrounding Laguna Lake. If appropriate, develop a sustainable groundwater indicator and associated information. 7. Oak woodlands. Conduct an assessment of oak woodlands within the SLO Valley Groundwater Basin to determine the oak species composition and distribution, with a particular focus on coast live oak riparian woodlands. Utilize existing wells or install new monitoring wells to monitor depth to groundwater. Utilizing the assessment and monitoring data determine if oak woodlands (e.g. Eastern Edna Valley) (Figure 2) are groundwater dependent. For example, coast live oak may have several deep main roots that tap groundwater if present within approximately 36 feet of the soil surface (Canadell et al 1996; Cooper 1922; Plumb 1980). If the oak woodlands are determined to be groundwater dependent, conduct an assessment of Pallid bat habitat distribution within oak woodlands and develop sustainable GDE indicators and associated data. 3.3 Identification of Sustainable GDE Indicators Each type of GDE (Table 2) has a different suite of fauna and flora associated with it. For some GDE types, we also identified associated sensitive natural communities (as identified by CDFW 2020 or CNPS 2020) or keystone species. Keystone species are defined as species that serve as indicators of GDEs sustainability. To develop indicators for each GDE type the requirements of sensitive or keystone species were considered. To this extent the life histories and habitat requirements of key faunal species are discussed in the following section, along with an explanation of the development of GDE indicators dependent on faunal species. 3.4 Life Histories and Habitat Requirements of Key Faunal Species 3.4.1 Key aquatic species Steelhead Steelhead have one of the most complex life histories of any salmonid species, exhibiting both anadromous and freshwater resident life histories. Freshwater residents are typically referred to as rainbow trout, and those exhibiting an anadromous life history are called steelhead (NMFS 1998). Stillwater Sciences 18 Page 551 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Steelhead exhibit highly variable life history patterns throughout their range but are broadly categorized into winter and summer reproductive ecotypes. Winter steelhead, the most widespread reproductive ecotype and the only type currently present in Central California Coast streams, become sexually mature in the ocean, enter spawning streams in summer, fall or winter, and spawn a few months later in winter or late spring (Meehan and Bjornn 1991; Behnke 1992).The timing of upstream migration is correlated with higher flow events, such as freshets or sand bar breaches, and seasonal decline of associated lower water temperatures in winter (NMFS 2006) Spawning occurs primarily from January through March but may begin as early as late December and may extend through April (Hallock 1987). Individual steelhead may spawn more than once, returning to the ocean between each spawning migration. Steelhead may spawn more than one season before dying (iteroparity), in contrast to other species of the Oncorhynchus genus. Upon emerging from the gravel, fry rear in edgewater habitats and move gradually into pools and riffles as they grow larger. Cover is an important habitat component for juvenile steelhead, both as velocity refuge and as a means of avoiding predation (Shirvell 1990, Meehan and Bjornn 1991). Steelhead, however, tend to use riffles and other habitats not strongly associated with cover during summer rearing more than other salmonids. In winter, they become inactive and hide in any available cover, including gravel, cobbles, or woody debris. Juvenile steelhead rear a minimum of one and typically two or more years in fresh water before migrating to the ocean during smoltification (the process of physiological change that allows ocean survival). Juvenile migration to the ocean generally occurs from December through August. Although various steelhead life stages occur in aquatic habitats that overly the SLO Groundwater Basin, these aquatic habitats are supported by a range of surface and groundwater sources (see Section 1 for discussion). However, during the late spring and dry season, the primary source supporting steelhead in GDEs overlying the SLO Valley Groundwater Basin is groundwater. Thus the dependence of steelhead on groundwater is greatest during the late spring and the summer -fall dry season and it is for these times of the year that target values for sustainable GDE indicators are proposed (Table 2). Target values are based on the best available data. In 2014 Stillwater Sciences completed a county -wide instream flow study for steelhead trout during their two most flow sensitive periods for minimum instream flows: late spring (May and June) and late summer (August and September) (Stillwater 2014). All available hydrologic and physical terrain data and instream flow assessments were reviewed and analyzed to explore appropriate watershed stratification and to assess the ability to extrapolate existing instream flow analyses throughout all watersheds of the County. A predictive model, based on watershed area, was developed to estimate minimum instream flows during these time periods. The purpose of the Stillwater (2014) study analysis was to provide a preliminary estimate of the magnitude and timing of instream flows that would support steelhead in creeks of SLO County and was not intended to provide sufficient precision or detail from which to establish regulatory limits. However, due to an absence of a detailed instream flow study in SLO Creek, this study is utilized to set preliminary target flow values herein. Two sites were selected for monitoring: Stenner Creek at the Nipomo Street Bridge and Mainstem SLO Creek at the Marsh Street Bridge (Table 2, Figure 3). These locations were selected because in the dry season these are in hydrologically gaining reaches, indicating that at the proposed locations the instream flows are primarily supported by SLO Valley Groundwater Basin groundwater. In Stenner Creek at Nipomo Street the sustainable flow target is set at 0.85 cfs for the late spring (May -June) and 0.33 cfs for the dry season (July -Oct) (SWS 2014) and at SLO Creek at the Marsh Street bridge the target is set at 1.20 cfs (late spring) and 0.90 cfs (dry season) (SWS 2014). To evaluate the approximate Stillwater Sciences 19 Page 552 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs streamflow values proposed herein, a detailed instream flow study for SLO Creek for SLO and Stenner Creeks is recommended. In 2016 Stillwater Sciences completed an instream flow study on Pismo Creek (Stillwater 2016). Based on this study, the streamflow target values recommended for mainstem Pismo Creek at the railroad crossing are set at 2.50 cfs in May, 1.50 cfs in June, and 0.50 cfs from July through the end of October. Similar to the approach used for SLO Creek, this location was selected for monitoring because it is located in a hydrologically a gaining reach and is likely supported by groundwater originating in the SLO Valley Groundwater Basin during the dry season. California Red -legged Frog (CRLF) CRLF is a federally listed as threatened and is a CDFW species of special concern. The species' range occurs from south of Elk Creek in Mendocino County to Baja California, with isolated remnant populations occurring in the Sierra foothills, from sea level to approximately 8,000 ft (Stebbins 1985, Shaffer et al. 2004). Most California red -legged frog populations are currently largely restricted to coastal drainages on the central coast of California. CRLF habitat includes wetlands, wet meadows, ponds, lakes, and low -gradient, slow -moving stream reaches. Breeding habitats are generally characterized by still or slow -moving water with deep pools (usually at least 2.3 ft deep, although frogs have been known to breed in shallower pools) with emergent and overhanging vegetation (Jennings and Hayes 1994). Breeding sites can be ephemeral or permanent; if ephemeral, inundation is usually necessary into the summer months (through July or August) for successful metamorphosis. Although some adults may remain resident year-round at favorable breeding sites, others may disperse overland up to a mile or more (Fellers and Kleeman 2007). Movements may be along riparian corridors, but many individuals move directly from one site to another without apparent regard for topography or watershed corridors (Bulger et al. 2003). CRLFs sometimes enter a dormant state during summer or in dry weather (aestivation), finding cover in small mammal burrows, moist leaf litter, root wads, or cracks in the soil. However, CRLFs in coastal areas are typically active year-round because temperatures are generally moderate (USFWS 2002, Bulger et al. 2003). The breeding (i.e., mating and egg -laying) season begins as early as late November and lasts though as late as April (Jennings and Hayes 1994). Females lay egg masses containing approximately 2,000-6,000 eggs (USFWS 2002). Eggs hatch within 6-14 days and tadpoles require approximately 11-20 weeks to metamorphose, generally from May to September (USFWS 2002), although overwintering by CRLFs has been documented at non -forested breeding sites (Fellers et al. 2001). CRLFs become reproductively mature frogs at 2 to 4 years, with females taking longer to develop (Jennings and Hayes 1994). Pools with water depths greater than 2.3 feet deep are optimal, though not required, to support a majority of the breeding and larval development periods. This water depth is used to set the sustainable GDE target value. Although CRLF begin to breed as early as late November, and tadpole growth and development continues through as late as September, the aquatic habitats utilized by CRLF are supported by a range of surface and groundwater sources throughout the year. However, during the late spring and dry season, the primary source supporting CRLF in GDEs overlying the SLO Valley Groundwater Basin is groundwater. For the slow moving riverine GDE type, the target values for sustainable GDE indicators are proposed based on CRLF requirements for the late spring and summer (Table 2). We propose that CRLF is a keystone species for the slow moving riverine GDE type, and if the proposed sustainable indicator criterion is met for the late spring and summer, it assumed that sufficient groundwater will be available Stillwater Sciences 20 Page 553 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs year-round for all habitats and species associated with this GDE type, including newts and western pond turtles. Coast Range New Coast Range newts occur commonly in the Coast Ranges from central Mendocino County south to northern San Diego County. Populations south of the Salinas River in Monterey County are considered by CDFW as a Species of Special Concern. Coast Range newts breed in ponds, reservoirs, and streams. Habitats are often in or near streams in valley -foothill hardwood and hardwood -conifer areas (Morey 1988); in southern California, suitable habitats include a generally drier zone of chaparral, oak woodland, or grassland. Stream -breeding newts in southern California commonly lay eggs in deep, slow pools, occasionally in runs, and almost never in riffles (Gamradt and Kats 1997, as cited in AmphibiaWeb 2020). Egg masses may be attached to aquatic vegetation, branches, and the outer surfaces of rocks; in southern California, egg masses are usually laid under rocks in quiet stream pools (AmphibiaWeb 2020) After metamorphosis, California newts disperse from aquatic habitats to terrestrial uplands. Deep leaf litter and animal burrows may be used as summer aestivation sites. During or after winter/spring rains, Coast Range newts return to their breeding site to mate, often migrating large distances and in large numbers. During a study by Trenham (1988), newts were recaptured up to 3,200 in (nearly two miles) away from the breeding pond where they were originally captured and marked. Migration from aestivation sites to breeding sites generally begins anywhere from late December to February, depending on the amount of rainfall, though populations that breed in stream pools migrate later, typically in March and April after stream flooding has subsided (Naffs 2020). Egg incubation to hatching times may vary at different locations, ranging from two weeks to two and a half months depending on water temperature, and the larval period lasts several months (Naffs 2020, AmphibiaWeb 2020). Larvae transform and begin to live on land at the end of the summer or in early fall, until as late as October (Naffs 2020). In summary stream -breeding Coast Range newts require quiet stream pools from March through October. Western Pond Turtle Western pond turtle is a CDFW species of special concern. Western pond turtles inhabit fresh or brackish water characterized by areas of deep water, low flow velocities, moderate amounts of riparian vegetation, warm water and/or ample basking sites, and underwater cover elements, such as large woody debris and rocks (Jennings and Hayes 1994). Along major rivers, western pond turtles are often concentrated in side -channel and backwater areas. Turtles may move to off - channel habitats, such as oxbows, during periods of high instream flows (Holland 1994). Although adults are habitat generalists, hatchlings and juveniles require specialized habitat for survival through their first few years. Hatchlings spend much of their time feeding in shallow water with dense submerged or short emergent vegetation (Jennings and Hayes 1994). Although an aquatic reptile, western pond turtles require upland habitats for basking, overwintering, and nesting, typically within 0.6 mi from aquatic habitats (Holland 1994). Reese and Welsh (1998) recorded frequent and prolonged year-round use of terrestrial habitat up to 0.3 mi (500 m) from the Trinity River for both nesting and overwintering activities. Western pond turtle eggs are typically laid in June and July, though they may be laid throughout the year (Holland 1994, Reese 1996); local climatic and water level variations can alter the timing of nesting in this species (Crump 2001). Egg -laying sites vary from sandy shorelines to various forest soil types, although they are generally located in grassy meadows, away from trees and shrubs (Holland 1994), with canopy cover commonly less than about 10% (Reese 1996). Incubating eggs are extremely sensitive to increased soil moisture, which can cause high mortality (Bettelheim 2005, Shaffer 2005, Ashton et al. 1997). Young hatch in late fall and Stillwater Sciences 21 Page 554 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs emerge either immediately or overwinter in the nest and emerge in early spring. Low fecundity, low hatchling and juvenile survivorships, high adult survivorship, and potentially long lifespans are characteristic of this species (Jennings et al. 1992). Western pond turtles have temperature - dependent sex determination, where the temperature of the egg during incubation determines the sex (Spinks et al. 2003). In summary, while pond turtles nest sites occur only in upland habitats, aquatic habitat is used year-round by foraging adults and juveniles, particularly deep pools with low flow. 3.4.2 Key birds Least Bittern Least bittern is a CDFW species of special concern. The smallest of the ardeids, they are cryptic marsh associates that are seldom seen. Because of their secretive nature, there are significant knowledge gaps regarding breeding behavior and interannual movement patterns. Breeding populations exist in small patches throughout the state but are concentrated in the Central Valley and along the Southern Coast (Sterling 2008; Poole et al. 2020), with some documented breeding populations in the eastern Sierra (Kirk 1995) and Klamath basin (Poole et al. 2020). SLO County is within the known breeding range (Sterling 2008). Least bittern are known to breed in both freshwater and brackish marshes (Sterling 2008, Poole et al. 2020), where they build nests atop platforms secured to the stalks of emergent vegetation (usually Typha or Scirpus spp., but occasionally Phragmites spp.) (Weller 1961, Poole et al. 2020). Nests are built up to 75 centimeters above the water surface where water depth is between eight centimeters and one meter. Least bittern show a preference for habitat that includes dense stands of emergent vegetation with adjacent pockets of open water. (Weller 1961, Poole et al. 2020). Breeding usually begins in late April and lasts through August (Kirk 1995, Sterling 2008, Poole et al. 2020). Population abundances decrease outside of the breeding season, which suggests seasonal migration, though some birds are likely winter residents. While foraging, least bittern stalk prey beneath the water surface by perching on the stalks of emergent vegetation (Weller 1961). Important food resources include small fish, terrestrial and aquatic invertebrates, amphibians, and occasionally small mammals (Weller 1961, Poole et al. 2020). Flooded stands of emergent vegetation are a critical requirement for successful breeding (minimum depth of 8 cm) and foraging. Maintaining stable water levels in Laguna Lake such that emergent vegetation on the lake margins remains inundated throughout the nest selection and breeding season (April —August) is the most important consideration for least bittern in the SLO watershed. However, the role of groundwater in maintaining these water elevations is unclear. Redhead A CDFW species of special concern, redheads are medium -bodied freshwater diving ducks (pochards) that occur throughout the United States. Pacific flyway redheads breed predominantly in Alaska, Canada, and the midwestern United States (Bellrose 1980, Beedy and Deuel 2008, Baldassarre 2014, Woodin and Michot 2020), however, resident populations occur year-round in California and breed in limited numbers from April through August (Gibbs et al. 1992 as cited in Beedy and Deuel 2008). 2019 CDFW breeding waterfowl surveys estimated 5,051 breeding individuals in the state, with a long-term average of 3,958 breeding individuals (Skalos and Weaver 2019). Seasonal migrants winter throughout California between September and April (Beedy and Deuel 2008, Baldassarre 2014). Resident breeding populations occur mostly in the Central Valley and the northeastern region of the state (in Siskiyou and Modoc County, and the Klamath Basin) (Bellrose 1980, Beedy and Deuel 2008). However, breeding occurrences have been documented outside of the "typical" range in Alameda, Monterey, and Ventura counties Stillwater Sciences 22 Page 555 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs (Beedy and Deuel 2008), so breeding could occur within the SLO watershed if habitat requirements for successful nesting are met. Redheads tend to build nests in dense stands of emergent vegetation (typically Typha and Scirpus spp.) over shallow water, though they have been recorded building ground nests in dense cover (Bellrose 1980, Baldassarre 2014, Beedy and Deuel 2008). Proximity to open water is a key requirement for successful breeding, as hens lead broods to water approximately one day after hatching (Bellrose 1980, Yerkes 2000, Baldassarre 2014). Redheads exhibit flexibility in foraging behavior, diving for submerged aquatic vegetation in water up to one meter deep, and tipping up or dabbling in shallower water (Bellrose 1980, Baldassarre 2014, Woodin and Michot 2020). Wigeon grass (Rupia spp.), duckweed (Lemna spp.), pond weed (Potamogeton and Stuckenia spp.), and both terrestrial and aquatic invertebrates are important food resources (Bellrose 1980, Baldassarre 2014, Woodin and Michot 2020). Most breeding pairs documented in California occupied permanent or semipermanent wetlands containing ponds with water deeper than one meter (CDFG and USFWS unpubl. data as cited in Beedy and Deuel 2008). Research in other geographic areas has tied reproductive success to water permanence, depth of water beneath nest sites, and overland distance from nest locations to foraging water (Bellrose 1980, Yerkes 2000). Other than maintaining a hydrologic regime conducive to the growth of critical forage plants and nesting substrate, the maintenance of permanent open water approximately one meter deep is the most important consideration for this species in the SLO watershed. For redheads, maintaining a depth of one meter in open water would be a good target for the breeding season for reproduction and year-round for wintering birds. However, the role of groundwater in maintaining open water is unclear. Tricolored blackbird Tricolored blackbird is listed as threatened by the state of California. Tricolored blackbirds are the most prodigious colonially nesting bird in North America (Cook and Toft 2005, Beedy et al. 2020). Endemic to California, their breeding range includes most of the Central Valley and parts of the Central and Southern California Coast (Beedy 2008, Beedy et al. 2020). SLO County is within the known breeding range (Beedy 2008), however in 2017 only three birds were observed breeding in the County during annual surveys (Meese 2017). Nest initiation begins in late March with breeding lasting through August (Beedy 2008, Wilson et al. 2016, Beedy et al. 2020). Historically, tricolored blackbird colonies nested in flooded stands of vegetation (particularly Typha spp. and Schoenoplectus spp.) (Cook and Toft 2005, Wilson et al. 2016, Beedy et al. 2020). However, since the arrival of Europeans in California, there has been an observable shift in behavior, with tricolored blackbirds often utilizing protective stands of non- native upland vegetation such as Himalayan blackberry (Rubus armeniacus). It is thought that this switch has resulted from the widespread degradation or outright disappearance of historic Central Valley wetlands. Colonies occupying non-native upland habitat exhibit increased reproductive success when compared to colonies that nest in native flooded vegetation (Cook and Toft 2005). Successful reproduction for tricolored blackbirds requires a combination of access to open water, appropriate nesting substrate, and proximity to high -quality foraging habitat (Beedy and Hamilton 1997). This species primarily feeds on terrestrial arthropods, including Coleoptera, Orthoptera, Diptera, Hemiptera, Arachnids, and Lepidoptera (Beedy and Hamilton 1997, Crase and DeHaven 1977). Colonies are usually located within a few kilometers of productive grassland, shrubland, forest, or agricultural land (Beedy and Hamilton 1997, Wilson et al. 2016). Stillwater Sciences 23 Page 556 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Maintaining open water in proximity to suitable nesting habitat (whether emergent vegetation or substantial stands of armored upland vegetation) during the nesting season would be a good target for this species. However, the role of groundwater in maintaining open water in proximity to nesting habitat is unclear. 4 PROPOSED SURFACE WATER MONITORING NETWORK Depending on location and time of year, GDEs that overly the SLO Valley Groundwater Basin can be supported by a range of water sources including direct precipitation, surface runoff, shallow subsurface flow, and groundwater. Shallow subsurface flow can vary from short-term precipitation driven flow (e.g. macro -pores filled during a precipitation event that drain on the order of days to weeks) to flow that is directly connected to groundwater (e.g. groundwater discharge into streams during the dry season). Because GDEs overlying the SLO Groundwater Basin are supported by a wider range of surface and groundwater hydrological processes in the wet season, we propose to focus monitoring of GDEs in the late spring baseflow period and summer/early fall dry season. During the late spring and summer/early fall dry season, the primary sources supporting these GDEs are likely groundwater, although in some reaches irrigation return flow may also be a factor. Irrigation return flow could have surface water sources from outside the basin (e.g. City of SLO parcels) or be dependent on local groundwater (e.g. Edna Valley). Base flows and groundwater levels during the late spring and summer/early fall dry seasons are also critical to ensure sustainable ecological conditions for many groundwater dependent species. Groundwater supporting GDEs overlying the SLO Valley Groundwater Basin can originate outside of the groundwater basin or within the groundwater basin. Our proposed monitoring network accounts for these two sources of groundwater by selecting locations that are likely primarily dependent of groundwater originating in the SLO Groundwater Basin. For example, proposed monitoring locations for instream flows (Table 3, Figure 4) are located in reaches that are likely hydrologically gaining in the late spring and dry season (Figure 1). Herein we assume that if the GDE indicators are met in the late spring and dry season, then sufficient groundwater would also be available in the wet season to sustain GDEs. However, we recommend that as more data becomes available, this assumption be revisited. 4.1 Proposed Monitoring Network Mainstem SLO Creek several hundred feet upstream of the Marsh St Bridge, September 2020 There are six existing County stage gages within or adjacent to the SLO Valley Groundwater Basin (Figure 3, Table 3). An additional three stage gages are proposed. These proposed stream gage locations may be modified as future work is completed in the basin. Rating curves, which correlate stage with stream flows, should be developed for all nine sites. In addition, we propose Stillwater Sciences 24 Page 557 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs that groundwater be monitored at all of these nine sites plus five additional sites (Figure 3, Table 3) for riparian and wetland/marsh GDE types. In addition to the above stage, stream flow, and groundwater monitoring, we recommend that streamflow is spatially mapped across a range of seasons and water year types to identify losing and gaining reaches with the SLO Groundwater Basin. Identifying losing and gaining reaches is fundamental to understanding surface -groundwater connectivity. This type of data collection is conducted by measuring instream flow in multiple locations along a reach of creek in a short period of time and examining the loss or gain of stream flow rates along the length of the stream channel. An example of this type of data collection on Stenner Creek is provided in Appendix C. Stillwater Sciences 25 Page 558 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Existing Gages and Proposed Monitoring Loactions Map Sources: Groundwater Basin: DWR for SLO Valley Groundwater Basin Roads, cities, rivers, waterbodies: ESRL 2016 Santa Fresno • Existing county stage gages Perennial Stream Cruz of • Proposed county stage gages Intermittent Stream • Proposed groundwater monitoring locations Waterbody Atascaderoo 0 Groundwater Basin o os I zMometel o 02sr 5 rO rT 1Miie I SbllwaterSciences Santa Barbara Figure 3. Existing and proposed monitoring locations for Groundwater Dependent Ecosystems. Stillwater Sciences 26 Page 559 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Table 3. Summary of proposed hydrologic monitoring for the SLO Valley Groundwater Basin. Proposed monitoring Sustainable GDE Water Body Location parameters Purpose Sustainable GDE indicators indicator target values Existing coun stage gage and proposed groundwater onitoring locations 1) Stage (ft) 1) Water budget Flow rate (cfs) 0.85 cfs (late spring); 1) Stenner Nipomo 2) Flow rate (ft/sec) 2) Surface -groundwater 0.33 cfs season)' Depth to groundwater below ground TBD Creek Street 3) Groundwater connectivity 3) Sustainable GDE elevation (ft) indicators surface (ft) 1) Flow into the basin for 2) Mainstem Andrews 1) Stage (ft) water budget 2) Surface -groundwater Depth to groundwater below ground TBD SLO Creek Street 2) Flow rate (ft/sec) surface (ft) connectivity 3 Sustainable GDE indicator 1) Stage (ft) 1) Water budget Flow rate (cfs) 1.20 cfs (late spring); 3 ) Mainstem 3) Marsh 2) Flow rate (ft/sec) 2) Surface -groundwater 0.90 cfs d season SLO Creek Street 3) Groundwater connectivity Depth to groundwater below ground TBD elevation 3) Sustainable GDE surface (ft) indicators 1) Stage (ft) 1) Water budget T4) Mainstem Elks Lane 2) Flow rate (ft/sec) 2) Surface -groundwater Depth to groundwater below ground TBD SLO Creek 3) Groundwater connectivity surface (ft) elevation 11 3 Sustainable GDE indicator 1 Stage ft g 1) Water budget 2) Surface -groundwater Water depth (ft) 2.3 feet$ (late spring and dry season) 5) East Fork Jespersen 2) Flow rate (ft/sec) connectivity Depth to groundwater below ground TBD SLO Creek Road 3) Groundwater 3) Sustainable GDE elevation (ft) Indicators surface (ft) 1) Stage (ft) 1) Water budget 6) Prefum Madonna 2) Flow rate (ft/sec) 2) Surface-groundwatero Depth to groundwater below ground Creek Road 3) Groundwater connectivity surface (ft) TBD elevation (ft) 3) Laguna Lake study 4 Sustainable GDE indicator 27 Stillwater Sciences Page 560 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Proposed monitoring Sustainable GDE Water Body Location parameters Purpose Sustainable GDE indicators indicator target values New proposed sta e gage andgroundwater monitoring locations 1) Stage (ft) 1) Flow into the basin for 7) Stenner Stenner 2) Flow rate (ft/sec) water budget 2) Surface -groundwater Depth to groundwater below ground TBD Creek Creek Road 3) Groundwater surface (ft) elevation (ft) connectivity 3 Sustainable GDE indicator Old bridge, 1) Stage (ft) 1) Flow out of the basin for 8) Mainstem near 2) Flow rate (ft/sec) water budget 2) Surface -groundwater Depth to groundwater below ground TBD SLO Creek Higuera 3) Groundwater connectivity surface (ft) Street elevation (ft) 3 Sustainable GDE indicator 1) Water budget 1.50 cfs (late spring)/; 1) Stage (ft) 2) Surface -groundwater Flow rate cfs ( ) 0.50 cfs season ) 9 Pismo Railroad 2 Flow rate ft/sec ( ) connectivity er 2 Stillwater 2016 Depth to groundwater below ground Creek Crossing 3) Groundwater 3) Sustainable GDE elevation (ft) indicators surface (ft) TBD New proposed groundwater nitoring locations 10) Tank Farm Near Tank Groundwater elevation GDE indicator Groundwater depth below surface (ft) TBD Wetlands Farm Rd (ft) 11) Davenport Crestmont Groundwater elevation GDE indicator Groundwater depth below surface (ft) TBD Creek Road (ft) 12) East Corral de Orcutt Groundwater elevation GDE indicator Groundwater depth below surface (ft) TBD Piedra Road (ft) 13) West Corral de Orcutt Groundwater elevation GDE indicator Groundwater depth below surface (ft) TBD Piedra Road (ft) 14) Canada Corbett Groundwater elevation GDE indicator Groundwater depth below surface (ft) TBD de Verde Canyon Rd ft Stillwater Sciences Page 561 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs In 2014 Stillwater Sciences completed a county -wide instream flow study for steelhead trout during their two most flow sensitive periods for minimum instream flows (late spring and later summer). A predictive model, based on watershed area, was developed to estimate minimum instream flows during these time periods. Values reported here are based on this model assuming that Stenner Creek at the Nipomo Street bridge has a watershed area of 11.0 square miles and SLO Creek at the Marsh Street Bridge has a 24.5 square mile watershed area s Jennings and Hayes 1994 Stillwater Sciences 2016 29 Stillwater Sciences Page 562 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs 5 REFERENCES Amlin, N. M., and S. B. Rood. 2002. Comparative tolerances of riparian willows and cottonwoods to water -table decline. Wetlands 22: 348-346. AmphibiaWeb. 2020. Taricha torosa. Information on amphibian biology and conservation. Berkeley, California. hqp://amphibiaweb.org/g_cai/g gmphibquery?where-genus=Taricha&where- species=torosa&account=amphibiawe Ashton, D. T., A. J. Lind, and K. E. Schlick. 1997. Western pond turtle (Clemmys marmorata). Natural history. USDA Forest Service, Pacific Southwest Research Station, Redwood Sciences Laboratory. Balance Hydrologics. 2008. Hydrology and Geology Assessment of Pismo Creek Watershed, San Luis Obispo County. Baldassarre, G.. 2014. Ducks, geese, and swans of North America. JHU Press. Barlow, P. M. and S. A. Leake. 2012. Streamflow depletion by wells: understanding and managing the effects of groundwater pumping on streamflow. Reston, VA: US Geological Survey. Beedy, E.C. and Hamilton, W.J., 1997. Tricolored blackbird status update and management guidelines. California Department of Fish and Game, Bird and Mammal Conservation Program. Beedy, E.C. 2008. Tricolored blackbird (Agelaius tricolor). In: Shuford, W. D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento Beedy, E.C. and Deuel, B.E. 2008. Redhead (Aythya americana). In: Shuford, W. D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento Beedy, E.C. and Deuel, B.E. 2008. Redhead (Aythya americana). In: Shuford, W. D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento Canadell, J.; Jackson, R. B.; Ehleringer, J. R.; Mooney, H. A.; Sala, O. E.; Schulze, E.-D. 1996. Maximum rooting depth of vegetation types at the global scale. Oecologia. 108(4): 583-595. Behnke, R. J. 1992. Native trout of western North America. American Fisheries Society, Bethesda, Maryland. 30 Stillwater Sciences Page 563 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Bellrose, F.C. and Kortright, F.H., 1980. Ducks, geese and swans of North America. Harrisburg. Bennett, S., 2015. Baseflow Data Compilation and GIS Analysis in San Luis Obispo Creek Watershed. Bettelheim, M. P. 2005. The western pond turtle, Clemmys marmorata. A natural history of the species. Privately published. California Department of Forestry and Fire Protection. 2015. Fire and Resource Assessment Program (FRAP) FVEG [ESRI File Geodatabase]. Sacramento, California. CDFW (California Department of Fish and Wildlife). 2019a. Special Vascular Plants, Bryophytes, and Lichens List. Quarterly publication. CDFW. 2019b. California Natural Diversity Database (CNDDB). 2019. Rarefind Version 5. Internet Application. CDFW, Sacramento, California. http://www.dfg.ca.gov/whdab/html/cnddb.html [accessed November 2019]. CDFW. 2020. List of California Sensitive Natural Communities. Vegetation Classification and Mapping Program, California Department of Fish and Game, Sacramento, California. December 2019. hgps://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=153609&inline CNPS (California Native Plant Society). 2020. Inventory of Rare and Endangered Plants of California (online edition, v8-03 0.39). California Native Plant Society, Sacramento, California. http://www.rareplants.cpps.org/ [Accessed October 2020]. Cook, L.F. and Toft, C.A. 2005. Dynamics of extinction: population decline in the colonially nesting tricolored blackbird Agelaius tricolor. Bird Conservation International, 15(1), pp.73-88. Cooper, William Skinner. 1922. The broad-sclerophyll vegetation of California: An ecological study of the chaparral and its related communities. Publ. No. 319. Washington, DC: The Carnegie Institution of Washington. 145 p. Crase, F.T. and Dehaven, R.W., 1977. Food of nestling tricolored blackbirds. The Condor, 79(2), pp.265-269. Creek Lands Conservation 2019. San Luis Obispo County Low Flow Monitoring Report (2015- 2018). Crump, D. E., Jr. 2001. Western pond turtle (Clemmys marmorata pallida) nesting behavior and habitat use. Master's thesis. San Jose State University, San Jose, CA. DWR (California Department of Water Resources). 2019. Natural communities commonly associated with groundwater database. hitps:Hgis.water.ca.gov/gpp/NCDatasetViewer/# accessed December 2019. eBird. 2017. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, New York. Available: http://www.ebird.org. (Accessed: Date [e.g., December 20191). Stillwater Sciences 31 Page 564 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs FGDC (Federal Geographic Data Committee). 2013. Classification of wetlands and deepwater habitats of the United States. FGDC-STD-004-2013. Second Edition. Wetlands Subcommittee, Federal Geographic Data Committee and U.S. Fish and Wildlife Service, Washington, D.C. Fellers, G. M., A. E. Laurier, G. Rathbun, S. Bobzien, J. Alvarez, D. Sterner, R. B. Seymour, and M. Westphal. 2001. Overwintering tadpoles in the California red -legged frogs (Rana aurora draytonii). Herpetological Review 32: 156-157. Gamradt, S. C. and Kats, L. B., 1997. Impact of chaparral wildfire -induced sedimentation on oviposition of stream -breeding California newts (Taricha torosa). Oecologia, 110: 546549. GSI. 2017. SLO Basin Characterization Figures and Tables. Hallock, R. J. 1987. Sacramento River system salmon and steelhead problems and enhancement opportunities. A report to the California Advisory Committee on Salmon and Steelhead Trout Holland, D. C. 1994. The western pond turtle: habitat and history. Final Report. U.S. Department of Energy, Bonneville Power Administration, Portland, Oregon. Jennings, M. R., M. P. Hayes, and D. C. Holland. 1992. A petition to the U.S. Fish and Wildlife Service to place the California red -legged frog (Rana aurora draytonii) and the western pond turtle (Clemmys marmorata) on the list of endangered and threatened wildlife and plants. Letter to M. Plenert, Regional Director, U.S. Fish and Wildlife Service, Region 1, Portland, Oregon. Jennings, M. R., and M. P. Hayes. 1994. Amphibian and reptile species of special concern in California. Final Report. Prepared by California Academy of Sciences, Department of Herpetology, San Francisco and Portland State University, Department of Biology, Portland, Oregon for California Department of Fish and Game, Inland Fisheries Division, Rancho Cordova. Kirk, A. 1995. First confirmed breeding record of the Least Bittern in Inyo County, California. W. Birds 26:165-166. Klausmeyer, K., J. Howard, T. Keeler -Wolf, K. Davis-Fadtke, R. Hull, and A. Lyons. 2018. Mapping indicators of groundwater dependent ecosystems in California. https://data. ca. gov/dataset/natural-communities-commonly-associated-groundwater Lewis, D. C., and R. H. Burgy. 1964. The relationship between oak tree roots and groundwater in fractured rock as determined by tritium testing. Journal of Geophysical Research 69: 2,579- 2,588. Mahoney, J. M., and S. B. Rood. 1998. Streamflow requirements for cottonwood seedling recruitment - an integrative model. Wetlands 18: 634-645. Meehan, W. R., and T. C. Bjonm. 1991. Salmonid distributions and life histories. Pages 47-82 in W. R. Meehan, editor. Influences of forest and rangeland management on salmonid fishes and their habitats. American Fisheries Society Special Publication No. 19. Bethesda, Maryland. Meese, R.J. 2017. Results of the 2017 Tricolored Blackbird Statewide Survey. Calif. Dept. of Fish and Wildlife, Wildlife Branch, Nongame Wildlife Program Report 2017-04, Sacramento, CA. 27 pp. + appendices. Stillwater Sciences 32 Page 565 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Morey, S. 1988. California newt Taricha torosa. Pages 14-15 in D. C. Zeiner, W. F. Laudenslayer, Jr., K. E. Mayer, and M. White, editors. California's wildlife. Volume I. Amphibians and reptiles. California Statewide Habitat Relationships System. California Department of Fish and Game, Sacramento. NAIP (National Agricultural Imagery Program). 2018. National Geospatial Data Asset (NGDA) NAIP Imagery. USDA-FSA-APFO Aerial Photography Field Office, Salt Lake City, UT. Nafis, G. 2020. A Guide to the Amphibians and Reptiles of California. Available at: hwww.californiaherps.com NMFS. 1998. A primer for federal agencies -essential fish habitat: new marine fish habitat conservation mandate for federal agencies. Habitat Conservation Division, Northeast Regional Office, Gloucester, Massachusetts NMFS. 2006. Endangered and Threatened Species: final listing determinations for 10 distinct population segments of West Coast steelhead. Federal Register 71: 834-862. NMFS (National Marine Fisheries Service). 2013. South -Central California Steelhead Recovery Plan. Prepared by NMFS, West Coast Region, Long Beach, California. Pierson, E D. and W. E. Rainey. 2002. Bats. Pages 385-400 in J.E. Vollmar, editor. Wildlife and rare plant ecology of eastern Merced County's vernal pool grasslands. Vollmar Consulting, Berkeley, California. Plumb, Tim R. 1980. Response of oaks to fire. In: Plumb, Timothy R., technical coordinator. Proceedings of the symposium on the ecology, management, and utilization of California oaks; 1979 June 26-28; Claremont, CA. Gen. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station: 202-215. Poole, A.F., Lowther, P.E., Gibbs, J.P., Reid, F.A. and Melvin, S.M. 2020. Least Bittern (Ixobrychus exilis), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/l0.2173/bow.leabit.01 Reese, D. A. 1996. Comparative demography and habitat use of western pond turtles in northern California: the effects of damming and related alterations. Unpublished doctoral dissertation. University of California, Berkeley. Reese, D. A., and H. H. Welsh. 1998. Habitat use by western pond turtles in the Trinity River, California. Journal of Wildlife Management 62: 842-853. Rohde, M. M., B. Seapy, R. Rogers, X. Castaneda, editors. 2019. Critical Species LookBook: A compendium of California's threatened and endangered species for sustainable groundwater management. The Nature Conservancy, San Francisco, California. Rood, S. B., and J. M. Mahoney. 1990. Collapse of riparian poplar forests downstream from dams in western prairies: probable causes and prospects for mitigation. Environmental Management 14: 451-464. Segelquist, C. A., M. L. Scott, and G. T. Auble. 1993. Establishment of Populus deltoides under simulated alluvial groundwater decline. The American Midland Naturalist 130: 274-285. Stillwater Sciences 33 Page 566 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Shaffer, H. B. 2005. Survival of pond turtles in modified waterways: how can it work, and why does it matter? Western Pond Turtle Workshop: ecology and conservation. 16 April, San Francisco, California. The Wildlife Society, San Francisco Bay Area Chapter. Shafroth, P. B., J. C. Stromberg, and D. T. Patten. 2002. Riparian vegetation response to altered disturbance and stress regimes. Ecological Applications 12: 107-123. Shapovalov, L. and A. C. Taft. 1954. The life histories of the steelhead rainbow trout (Salmo gairdnerii) and silver salmon (Oncorhynchus kisutch) with special reference to Waddell Creek, California, and recommendations regarding their management. Calif. Dept. Fish and Game, Fish Bull. No. 98. 373 pp. Shirvell, C. S. 1990. Role of instream rootwads as juvenile coho salmon (Oncorhynchus kisutch) and steelhead trout (O. mykiss) cover habitat under varying instream flows. Can. J. Aquat. Sci., Vol 47:852-861. Skalos, D., and Weaver, M. 2019. Preliminary 2019 California Waterfowl Breeding Population Survey Report. California Department of Fish and Wildlife (CDFW) Wildlife Branch/Waterfowl Program, Sacramento. Spinks, P. Q., G. B. Pauly, J. J. Crayon, and H. B. Shaffer. 2003. Survival of the western pond turtle (Emys marmorata) in an urban California environment. Biological Conservation 113:257-267. Sterling, J. 2008. Least bittern (Ixobrychus exilis). In: Shuford, W. D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento Stillwater Sciences. 2016. Pismo Instream Flow Study. Prepared by Stillwater Sciences, Morro Bay, California for Creek Lands Conservation, Arroyo Grande, California. Stillwater Sciences. 2014. San Luis Obispo County regional instream flow assessment. Prepared by Stillwater Sciences, Morro Bay, California for Coastal San Luis Resource Conservation District, Morro Bay, California. TNC (The Nature Conservancy). 2019. Freshwater species list for San Luis Obispo Valley Groundwater Basin. https:Hgroundwaterresourcehub.org/sgma-tools/environmental-surface- water-beneficiaries Trenham, P.C. 1998. Demography, migration, and metapopulation structure of pond breeding salamanders. Ph.D. dissertation. University of California, Davis, California. USFWS (U.S. Fish and Wildlife Service). 2002. Recovery plan for the California red -legged frog (Rana aurora draytonii). U.S. Fish and Wildlife Service, Portland, Oregon. USFWS. 2018. National Wetlands Inventory website. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. http://www.fws.gov/wetlands/ Stillwater Sciences 34 Page 567 of 1183 Technical Memorandum SLO Valley Groundwater Basin GDEs Vaghti, M. G., and S. E. Greco. 2007. Riparian vegetation of the Great Valley. Pages 425-455 in M. G. Barbour, T. Keeler -Wolf, and A. A. Shoenherr, editors. Terrestrial Vegetation of California, Third Edition. University of California Press, Berkeley. Weller, M.W„ 1961. Breeding biology of the Least Bittern. The Wilson Bulletin, pp. 11-35. Wilson, C.R., Meese, R.J. and Wyckoff, A.C., 2016. Breeding chronology, movements, and life history observations of Tricolored Blackbirds in the California Central Coast. California Fish and Game, 102(4), pp.162-174. Woodin, M.C. and Michot, T.C. 2020. Redhead (Aythya americana), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. httns:Hdoi.ora/10.2173/bow.redhea.01 WSC (Water Supply Consultants). In progress. Draft San Luis Obispo Valley Groundwater Sustainability Plan. Yerkes, T. 2000. Nest -site characteristics and brood -habitat selection of redheads: an association between wetland characteristics and success. Wetlands, 20(4), p.575. Stillwater Sciences 35 Page 568 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Appendices Stillwater Sciences Page 569 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Appendix A Basin Sediment Thickness Map (GSI 2017) Stillwater Sciences Page 570 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Distancein Mlles r ' Bedrock 0wide ' 'b JQ] tJ 4 � �[ 'b mob°' • % ','� $• Watershed DIVIdC ' 8 i l Figure A-1. SLO Groundwater Valley Basin Sediment Thickness Map (GSI 2017). Figure 4 Basin Sediment Thickness Map San Luis Obispo Valley Basin Characterization LEGEND 1� Bulleun 11a Basin Boundary — Sediment Thekness Contour -Index — Sedlment Thekness Contour - Minor • Bedn-k Depth gala Paint --giludinal Seaton Una Reed• Sadmant Thlcknns {foal] D 0 ton 0 20D 0 30D JOD CQMGbr Irter0l; 4Q Feat . ■Y ke16 4irSPtl C6uMTr M I�'Ll P1•'..m it ��.�+ od�po.um Stillwater Sciences A-1 Page 571 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Appendix B Fall 1954 Water Level Map (GSI 2017) Stillwater Sciences Page 572 of 1183 Technical Memorandum lotm; 9M tn.Oh4D "Wren vtt w■b r�l.oam.aa�.o� Nu 14 F r I% WFMA Approximate groundwater flow direction SLO Vallev Groundwater Basin GDEs FIGURE 22 Fall 16o 4 Waller Level Map San U15 Obispo Valley Basin Cilhowlewilon RS1 MES Figure B-1. SLO Groundwater Valley Basin 1954 Water Level Map (Data from DWR, Figure from GSI 2017; direction of groundwater flow (red arrows) added by Stillwater Sciences) 10 Stillwater Sciences Page 573 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Appendix C Map of Gaining and Losing Instream Flow Conditions, Stenner Creek, September 2020 (Creek Lands Conservation, unpublished data) Stillwater Sciences Page 574 of 1183 Technical Memorandum SLO Vallev Groundwater Basin GDEs Legend — Stenner Creek Stenner Creek Watershed SLO Creek © Fox Hollow Enhancement Reach ❑ SLO Creek Watershed Flow Points o Satisfies dry seasonEW❑ o Below dry season FWD 1 Qi4 -q r ...+ =' . y �.�4 cf 5 0.69 cfs Stenner Creek Water Resilience and Stream Flow Enhancement REEK ALANDS to' conservation Flow measurements from August 28 0 0.5 1 mi and September 3, 2020 Map Date: 08 September 2020 1:55000 Author Creek Lands Conservation Figure C-1. Stenner Creek flow rate (cfs) as measured by Creek Lands Conservation (CLC) in late August/early September 2020 showing losing and gaining hydrologic conditions. Flow is also compared to environmental water demand (EWD) as defined by Stillwater Sciences (2014). (Figure by CLC) Stillwater Sciences C-1 Page 575 of 1183 Page 576 of 1183 DIW- --I . This Memorandum of Agreement ("MOX) is entered into by and between the City of San Luis Obispo ("City"), the County of San Luis Obispo ("County"), the Edna Valley Growers Mutual Water Company ("EVGMWC"), the Varian Ranch Mutual Water Company ("VRMWC"), the Edna Ranch Mutual Water Company ("ERMWC") and the Golden State Water Company ("GSWC") (each referred to individually as a "Party" and collectively as the "Parties") for purposes of coordinating preparation of a single groundwater sustainability plan for the San Luis Obispo Valley Groundwater Basin. WHEREAS, on September 16, 2014, Governor Jerry Brown signed into law Senate Bills 1168 and 1319 and Assembly Bill 1739, known collectively as the Sustainable Groundwater Management Act ("SGMA"), which became effective on January 1, 2015 and which have been and may continue to be amended from time to time; and WHEREAS, SGMA requires the establishment of a groundwater sustainability agency ("GSA!') or agencies for all basins designated as medium- or high -priority by the Department of Water Resources ("DWR") on or before June 30, 2017; and WHEREAS, SGMA further requires the adoption of a groundwater sustainability plan ("GSP") or coordinated GSPs for all basins designated by DWR as medium- or high -priority and not subject to critical conditions of overdraft on or before January 31, 2022; and WHEREAS, DWR has designated the San Luis Obispo Valley Groundwater Basin (Basin No. 3-9) ("Basin") as a medium -priority basin not subject to critical conditions of overdraft; and WHEREAS, the County and the City have each decided to become the GSA within their respective service areas overlying the Basin and have informed DWR of their decision and intent to undertake sustainable groundwater management therein; and WHEREAS, the County and the City desire to collectively develop a single GSP to sustainably manage the Basin; and WHEREAS, the County and the City further desire to include the other Parties to this MOA who each constitute entities eligible to participate in a GSA (sometimes referred to individually as a "Participating Party" or collectively as the "Participating Parties") in the development of the GSP through the creation of the Groundwater Sustainability Commission. Page 1 of 9 Page 577 of 1183 NOW, THEREFORE, it is mutually understood and agreed as follows: Section 1 Purpose This MOA is entered into by the Parties for the purpose of establishing the manner in which the City and the County, with input from the Participating Parties, will coordinate in the development of a single GSP for the Basin that will be considered for adoption by the City Council and the County Board of Supervisors and subsequently submitted to DWR for approval. This MOA may also serve as the basis for continued cooperation among the City and the County in the management of the Basin during the period between adoption of the GSP by the City Council and the County Board of Supervisors and approval of the GSP by DWR. As more specifically set forth in Section 10.3 below, this MOA shall automatically terminate upon DWR's approval of the GSP for the Basin. Section 2 Term This MOA shall become effective on the date that the last of the six (6) Parties signs ("Effective Date") and shall remain in effect until terminated in accordance with Section 9.2 or Section 10.3 below. Section 3 City and County Roles and Responsibilities 3.1 The City and the County shall workjointly to meet the objectives of this MOA. 3.2 The City and the County shall retain the services of a consultant(s) to meet the objectives of this MOA, including, but not limited to, preparation of a GSP for the Basin in accordance with the provisions set forth in Section 7 below. 3.3 The City and the County shall each designate a staff person(s) to participate in the development of the GSP and related technical studies through, without limitation, the provision of guidance and available data, in coordination with the consultant(s), and to administer the Groundwater Sustainability Commission (e.g. to, among other things, timely publish all agendas and take minutes). 3.4 The City and the County shall each be responsible for adopting the GSP and implementing the GSP within their respective service areas. Notwithstanding the foregoing, nothing contained in this MOA shall be construed as obligating either the City Council or the County Board of Supervisors to adopt the GSP developed pursuant to this MOA or as preventing either the City Council or the County Board of Supervisors from adopting the GSP developed under this MOA in the event that the other elects not to adopt it or in the event that the Groundwater Sustainability Commission fails to recommend approval. Page 2 of 9 Page 578 of 1183 3.5 The City and the County may lead certain Basin -wide public outreach and stakeholder involvement to improve development of the GSP. 3.6 The City shall be responsible for taking all legally required actions associated with its appointment of the member and alternate member to the Groundwater Sustainability Commission representing the City as set forth in Section 4.5, including, without limitation, all applicable requirements under the Maddy Act (Government Code §§ 54970 et seq.) and the County shall be responsible for taking all such actions associated with its appointment of the member and alternate member to the Groundwater Sustainability Commission representing the County and its confirmation of the members and alternate members to the Groundwater Sustainability Commission representing the Participating Parties as set forth in Section 4.4 and Section 4.3, respectively. Section 4 Establishment of the Groundwater Sustainability Commission 4.1 The City and the County hereby establish the Groundwater Sustainability Commission to serve as an advisory committee to the City Council and the County Board of Supervisors in connection with preparation of the GSP and interim Basin management actions subject to each Participating Party making its required contributions under Section 6(B). 4.2 The Groundwater Sustainability Commission shall be composed of five (5) members: one (1) member representing the City, one (1) member representing the County, one (1) member representing EVGMWC, one (1) member collectively representing VRMWC and ERMWC and one (1) member representing GSWC. 4.3 Each of the Participating Parties shall nominate a member and an alternate member to represent it on the Groundwater Sustainability Commission subject to confirmation by the County Board of Supervisors with the exception that VRMWC and ERMWC shall jointly nominate a member and an alternate member to represent them subject to confirmation by the County Board of Supervisors. Said members shall serve at the pleasure of the County Board of Supervisors and may be removed at any time provided that the County Board of Supervisors shall have no authority to replace a removed member with an individual who has not been nominated by the relevant Participating Party or collection of Participating Parties. 4.4 The County Board of Supervisors shall appoint the member and alternate member representing the County and said members shall serve at the pleasure of the County Board of Supervisors. 4.5 The City Council shall appoint the member and alternate member representing the City and said members shall serve at the pleasure of the City Council. Page 3 of 9 Page 579 of 1183 4.6 All meetings of the Groundwater Sustainability Commission shall be conducted in accordance with the Ralph M. Brown Act (Government Code §§ 54950 et seq.). 4.7 A majority of the members of the Groundwater Sustainability Commission shall constitute a quorum for purposes of transacting business, except that less than a quorum may vote to adjourn the meeting. 4.8 Each member of the Groundwater Sustainability Commission shall be entitled to one (1) vote on any matter under consideration by the Groundwater Sustainability Commission. 4.9 All advisory opinions submitted by the Groundwater Sustainability Commission to the City Council and the County Board of Supervisors shall be supported by a majority of the members, except for the recommendation to adopt the GSP or any amendments thereto which shall be supported by at least four (4) of the members. 4.10 The County Board of Supervisors and the City Council may approve or reject any advisory opinion submitted by the Groundwater Sustainability Commission provided that in every case that the County Board of Supervisors or City Council rejects an advisory opinion of the Groundwater Sustainability Commission related to the contents or adoption of the GSP it shall do so only after holding a public hearing, at which time the members of the Groundwater Sustainability Commission shall have the right to appear and address the City Council and the County Board of Supervisors. 4.11 None of the members or alternate members shall be entitled to any compensation from the County or the City for their service on the Groundwater Sustainability Commission. Section 5 Establishment of Additional Advisory Committees The City Council and the County Board of Supervisors may from time to time jointly establish one or more additional advisory committees or establish standing or ad hoc committees to assist in carrying out the purposes and objectives of this MOA. Without limiting the foregoing, it is anticipated that the City Council and the County Board of Supervisors will establish a stakeholder advisory committee to the Groundwater Sustainability Commission to consider the interests of beneficial uses and users not already represented on the Groundwater Sustainability Commission consistent with Water Code Section 10723.2. Page 4 of 9 Page 580 of 1183 U=- The City and the County agree to jointly fund the costs associated with implementation of this MCA in accordance with and subject to the following: A. Within sixty (60) days of the Effective Date and prior to each anniversary of the Effective Date, City and County staff shall prepare an annual budget for the GSAs to implement this MCA for approval by the City Council and the County Board of Supervisors. B. Each of the Participating Parties shall be responsible for contributing the following funds to help defray the costs of the Groundwater Sustainability Commission and in consideration for their participation thereon within thirty (30) days of the Effective Date and within thirty (30) days of each anniversary of the Effective Date: EVGMWC $28,200 VRMWC $4,550 ERMWC $4,550 GSWC $12,700 C. Subject to City Council and County Board of Supervisor approval of the annual budget, the City and County agree to fund the annual budget (less the contributions set forth in Section 6(B)) in accordance with the percentage allocations set forth below. Notwithstanding the foregoing and Section 10.1, the City Council and the County Board of Supervisors may amend said percentage allocations without the agreement of the Participating Parties. County 70% City 30% D. It is anticipated that the vast majority of budgeted costs to be paid by the City and the County will involve costs for consultant services. Consequently, most City and County contributions will be paid in the manner described in Section 7 below. ZT-TMI. M Retention of Consultants 7.1 The County agrees to act as the contracting agent to retain the services of a consultant(s) as described in Section 3.2 above. 7.2 Notwithstanding the foregoing, the County agrees that the City and one (1) member of the Groundwater Sustainability Commission not representing the City or the County designated by the Groundwater Sustainability Commission shall be included in the I selection of any consultant retained by the County pursuant to this MOA. More specifically, Page 5 of 9 Page 581 of 1183 a staff representative from the City and the designated member of the Groundwater Sustainability Commission shall be given an opportunity to review and approve all requests for proposals prior to their release and to participate in the various stages of the selection process, including, but not limited to, review of proposals and participation on interview panels. 7.3 All consultant contracts entered into by the County pursuant to this MOA shall include the following: (1) a provision requiring that the consultant name the City as an additional insured, (2) an expected spend plan estimating the amount of the not to exceed contract amount that the consultant expects to invoice each month, and (3) a provision requiring that the consultant calculate both the County and City's share of each invoice consistent with Section 6(C) and send monthly invoices to both the County and the City showing the foregoing calculation. 7.4 Both the City and the County shall be responsible for remitting payment of their share of each monthly invoice directly to the consultant within thirty (30) days of receipt or within the time frame otherwise set forth in the consultant contract. Section 8 Notice 8.1 To provide for consistent and effective communication among the Parties, each Party shall designate a representative as its central point of contact on matters relating to this MOA. 8.2 All notices, statements, or payments related to this MOA shall be deemed to have been duly given if in writing and delivered electronically, personally or mailed by first- class, registered or certified mail to the Parties at the addresses set forth in Exhibit A. The Parties may update Exhibit A from time to time without formal amendment to this MOA. Section 9 Withdrawal and Termination 9.1 Any Participating Party may unilaterally withdrawal from this MOA without causing or requiring termination of this MOA. Withdrawal shall become effective upon thirty (30) days written notice to the remaining Parties' designated addresses as listed in Exhibit A. A Participating Party that has withdrawn from this MOA shall remain obligated to pay its allocation of the current annual budget. If a Participating Party withdraws, the Groundwater Sustainability Commission shall automatically be reconstituted to no longer include a member or alternate member representing the withdrawing Participating Parry. In addition, the withdrawing Participating Party's annual contribution as set forth in Section 6(B) for all subsequent years shall be allocated among the remaining Participating Parties on a pro rata basis. Page 6 of 9 Page 582 of 1183 9.2 This MOA may be terminated by either the City or the County upon thirty (30) days written notice to all Parties' designated addresses as listed in Exhibit A. Upon termination, any unused portion of the cost contributions described in Section 6(B) and Section 6(C) as of the effective date of termination shall be returned to each Party on a pro rata basis. If the City terminates this MOA, it shall remain obligated to pay its cost share obligation under any existing consultant contract entered into by the County pursuant to this MOA. Section r 10.1 Subject to the exception set forth in Section 6(C), this MOA may be amended only by unanimous written consent of all current Parties. 10.2 This MOA may be executed in counterparts. 10.3 This MOA shall automatically terminate upon DWR's approval of the adopted GSP. Depending on the content of the GSP, the Parties may decide to enter into a new agreement to coordinate GSP implementation. 10.4 This MOA is made in the State of California, under the Constitution and laws of said State and is to be so construed. 10.5 If any provision of this MOA is determined to be invalid or unenforceable, the remaining provisions shall remain in full force and unaffected to the fullest extent permitted by law and regulation. 10.6 This MOA constitutes the sole, entire, integrated and exclusive agreement between the Parties regarding the contents herein. Any other contracts, agreements, terms, understandings, promises or representations not expressly set forth or referenced in this writing are null and void and of no force and effect. 10.7 The Parties agree and acknowledge that this MOA has been developed through negotiation, and that each Party has had a full and fair opportunity to revise the terms of this MOA. Consequently, the normal rule of construction that any ambiguities are to be resolved against the drafting party shall not apply in construing or interpreting this MOA. [signatures to follow on next page] Page 7 of 9 Page 583 of 1183 IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO By: Its: Date: APPROVED AS TO FORM AND LEGAL EFFECT: By: Its: Date: EDNA VALLEY GROWERS MUTUAL WATER COMPANY By: Its: Date: EDNA RANCH MUTUAL WATER COMPANY By: Its: Date: COUNT-r IJLUA OBISPO B iu Date APPROVED AS TO FORM AND LEGAL EFFECT: Its: Date:l� VARIAN RANCH MUTUAL WATER COMPANY By: Its: Date: GOLDEN STATE WATER COMPANY By: _ Its: Date: Page 8 of 9 Page 584 of 1183 IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO By: Its: Date: APPROVED AS TO FORM AND LEGAL EFFECT: By: Its: Date: COUNTY OF SAN LUIS OBISPO By: JOHN PESCHONG Its: OlVao"ObISPO, Date: Ja-nuc-qrV '3, 20115 APPROVED AS TO FORM AND LEGAL EFFECT: AVM: Tommy Gong, County Clerk , Recor(Jer and By: Ex-Officio; Clerk of the Board of Supervisors &ANDY CUR-FIEN'S sy..-W- - - woom Its: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATPR COMPANY WATER COMPANY I rf By: By: Its: Its: Date: t 2- /12 Date: f EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY &TI-A 14 a2iii1ri By: By: Its: Its: Date: Date: Page 8 of 9 Page 585 of 1183 IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF S N LUIS O O By: Its: Date: ( �' APPROVED AS TO FORM AND LE( By: Its: Datd: I EDNA VALLEY GROWERS MUTUAL WATER COMPANY By: Its: Date: EDNA RANCH MUTUAL WATER COMPANY By: Its: Date: COUNTY OF SAN LUIS OBISPO By: Its: Date: APPROVED AS TO FORM AND LEGAL EFFECT: By: - 4;99 Its: G *2:199 Date: Af[::r-'Y• 4t ��l �- VARIAN RANCH MUTUAL WATER COMPANY By: Its: Date: GOLDEN STATE WATER COMPANY By: Its: Date: Page 8 of 9 Page 586 of 1183 EXHIBIT A PARTY ADDRESS LIST County of San Luis Obispo County Government Center, Room 206 San Luis Obispo, CA 93408 Attention: Wade Horton, Public Works Director City of San Luis Obispo Utilities Department 879 Morro Street San Luis Obispo, CA 93401-2710 Attention: Carrie Mattingly, Utilities Director Edna Valley Growers Mutual Water Company 4910 Edna Road San Luis Obispo, CA 93401 Attention: Bob Schiebelhut, President Varian Ranch Mutual Water Company 2060 Varian Circle Arroyo Grande, CA 93420 Attention: James Lokey Edna Ranch Mutual Water Company 5665 Edna Ranch Circle San Luis Obispo, CA 93401 Attention: Andy Mangano Golden State Water Company 2330 A Street, Suite A Santa Maria, CA 93455 Attention: General Manager, Coastal District Page 9 of 9 Page 587 of 1183 Page 588 of 1183 PARTY ADDRESS LIST County of San Luis Obispo County Government Center, Room 206 San Luis Obispo, CA 93408 Attention: Wade Horton, Public Works Director City of San Luis Obispo Utilities Department 879 Morro Street San Luis Obispo, CA 93401-2710 Attention: Carrie Mattingly, Utilities Director Edna Valley Growers Mutual Water Company 4910 Edna Road San Luis Obispo, CA 93401 Attention: Bob Schiebelhut, President Varian Ranch Mutual Water Company 2060 Varian Circle Arroyo Grande, CA 93420 Attention: James Lokey Edna Ranch Mutual Water Company 5665 Edna Ranch Circle San Luis Obispo, CA 93401 Attention: Andy Mangano Golden State Water Company 2330 A Street, Suite A Santa Maria, CA 93455 Attention: General Manager, Coastal District Page 9 of 9 Page 589 of 1183 IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO By: Its: Date: APPROVED AS TO FORM AND LEGAL EFFECT: By: Its: Date: EDNA VALLEY GROWERS MUTUAL WATER COMPANY By: Its: Date: EDNA RANCH MUTUAL WATER COMPANY By: Its: Date: COUNTY OF SAN LUIS OBISPO By: Its: Date: APPROVED AS TO FORM AND LEGAL EFFECT: By: _ Its: Date: VARIAN RANCH MUTUAL WATER OMPANY By:. L2''� Date: GOLDEN STATE WATER COMPANY By: Its: Date: Page 8 of 9 Page 590 of 1183 IN WITNESS WHEREOF, the Parties have executed this. MOA by authorized officials thereof on the dates indicated below. CITY OF SAW LUIS OBISPO COUNTY OF SAN LUIS OBISPO By: By: Its: Its: Date: 'Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGALVIFFECT: By: BY: Its: Its: Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDNA�ANCH MUTUAL GOLDEN STATE WATER COMPANY W)A-1.Z_ IPANY By: Q By: Its: Elv Its: Date: — IIA-1 1-7 V I , Date: Page 8 of 9 Page 591 of 1183 IN WITNESS WHEREOF, the Parties have executed this MOA by authorized officials thereof on the dates indicated below. CITY OF SAN LUIS OBISPO COUNTY OF SAN LUIS OBISPO By: By: Its: Its: Date: Date: APPROVED AS TO FORM AND APPROVED AS TO FORM AND LEGAL EFFECT: LEGAL EFFECT: By: By: Its: Its: Date: Date: EDNA VALLEY GROWERS VARIAN RANCH MUTUAL MUTUAL WATER COMPANY WATER COMPANY By: By: Its: Its: Date: Date: EDNA RANCH MUTUAL GOLDEN STATE WATER COMPANY WATER COMPANY By: By: Its: Its: Sr: Vi'c . PKbIaL1 ►+ Date: Date: W �y+_'�,� 3; k;-Di l Page 8 of 9 Page 592 of 1183 Purpose of Today's Study Session 1. Council to receive a presentation on SGMA Groundwater Sustainability Plan Development. 2. Council to provide feedback on the Groundwater Sustainability Plan prior to the item returning to City Council for final adoption on December 7, 2021. SGMA Legislation Background • SGMA was adopted by the State in 2014. • Required that local agencies form Groundwater Sustainability Agencies (GSAs) for high and medium priority groundwater basins in California. • Required GSAs to develop and implement Groundwater Sustainability Plans (GSPs) in order to avoid "Undesirable Results" and mitigate basin overdraft within 20-years (2022-2042). • The City of SLO overlies the San Luis Valley Groundwater Basin which was deemed as "High -Priority" by the State of California. • A GSP must be completed for the San Luis Valley Groundwater Basin by January 31, 2022 Governance Structure & GSP Adoption 0 CITY OF SLO GSA 9nk COUNTY OF SLO GSA MYCHAL BOERMAN diGSA $TAPE---- } DICK TZCU, PE Deputy Director of Water, Water Resources Engineer, Cif y of San Luis Obispo County of San Luis Obispo EDNryAVALLEY Go GROWERS %k IYi TY c AWN ORTIZ LEGG ANDY PEASE BOB SCHIEBELHUT Member me»lbfr Chair BRUCEGIBSON AARONFLOYD GEORGEDONATi Ahernate Alf. -male Ahernale EDNA RANCHAND VARIAN��RANCH M YY c DENNIS FERNANDEZ Member JAMES LOKEY Alternate Golden State t�■ 1dl �ti� Com Oaflr MARKZIMMER Vice Choir TORY MOORE Alternate Governance Structure & GSP Adoption rE �,._ _ l�nr-���---�—: �-r :° � ••�'•� �Y � ` ram. r � e7 . r' � 1 w � Tf . �s . •. r. r v' iZ iaSA Sw 1.! yL/a+ajjy,�. L-oil 1 so`il:cb:P� a r '. I •fir ���'• Explanation MOA Partwipaling Parties Edna Valley Growers �. MWC Edna Ranch MWC - East Golden Slate WC - Edna Varian Ranch MWC Groundwater Sustainability Agencies City or San Luis Obispo GSA County of San Luis Obispo GSA Surface Water Sources Lakes and Reserviors - Surface Water Pty: p■s.�N ��yy y • r �... ', ._ w '' iI. JI i �r �f _ � � " !a ��r �, 7T t� •� r. � ri / San Luis Obispo Bay ...�.. . �..ii ..i.... I.� ... .... in—r :a^nr^r.�r_c MFS:Airlri,x iS ilS.1. l.SnS Av^C;RIn ..n.-: lir r:'.`. i.si�%f. n-ni-i:ii�i•. Basin Geology and Geography Explanation 0 Buletin 118 Basin Boundary BedrwkElevkmCwtour-Index r, .. } 9edlndc £levatlon Contour - N91roor Bedrock CkWh Bata Pole Longitudinal Section Line f + — Road Bedrock Elevziia {Feet amsFj •1W ' San iF11s d sF,o f 4 Tao i r:i x 0 2W rr � $r 0 394 r � f It ` " f Watershed Divide A,, a Bedrock Divide ,,:�► g� 9EDi{O � � i ■E9 FOCL y� +.., . -� i +- ti � � .h `•. 5 • u 17t5{aRGP tf1 Yu1 P5 r - - - - _ - - _ - - 1 . w n Ar Changes in Groundwater K, P 1 5 M 0 8 E A G H Elevation 1997-2011 F, A N I �u J a no 0 r ti .44 ;e�' zzi� Explanation — — bedrock Divide 0 San Luis Obispo Valley 90sirk Water Level Change Spring IMUsSpirmq 2011 � so feet -130 to -50 Feet [j -60 to 40 FEBI -40 to -N feet —30 to -20 lent -20 W -10 le -et - 10 to 0 feel , 10 feet AH Other Futures .j City Boundary 11V Mf3PF Rood Mtefccurse YYWOrb0dy Afl, (GSP Chapter 5) n ge, in Gro u n dwatar Elevation Spring 1997 to Spring 2011 PI S rA0 B E A D H Changes in Groundwater Elevation 2011=2 5 r�u F 3 { 1r le �dlh.►4 {J'- r---�.. iM1N FIWNwG /�5 Explanation — — Badrvek Divide 0 San Luis Obispo Valley Bawn Water Level Chang Spring 2011 to Spring 2015 -50 feet -80 to -60 taut SO to 40 lant p -40 to -30 feet -30 to -n feel [] -20 to -10 fam Q -10 to 0 Fool 10 feet AN Other '"tunes City Boundary N Majoridoad Walercourse ,f Mlerbudy r ".1, (GSP Chapter 5) nge in Groundwater Elevation Spring 2011 to Spring 2015 Changes in Groundwater Levels ira lid-4i4 a lied ISO 40 an m Sm UK in Epp 290 2010 � 2 Jim 1 1 � Iwo no Lf70 Hm Ilm 1L00 }DID 7000 rto r W Im 1!0 i 1990 Im 1170 19l0 1910 WN 2010 1029 220 � j1W j 160 00 W--�.. 195U 1960 S979 19e0 19M 2000 2010 202CI P I S M 9 roo �._ ifa - Explanation 1W - Lfa� r !7d I Bedrock 0141de V yjd Giy Boundary MJUFc04Jlse j t�+1�rM"" dim ?� Major Road M011110ring A1ea Associated .120 '100 N HN-graphs) 00, s0 [3 Sort Luis Obispo Yalley Bas1n 19" 1960 1970 1990 19W 2000 1010 2020 Im Im Im on Im xao0 Zl zamo ~ T� N1L pJ1,+lm + • 210 � 7>p 4 1 � Vol ri0 Sng ✓� � � ifd ��� 17d 1960 197d 19b ]'F'MY ldld 1d 10 ldld ,M I lJ . f e 200 _ 1950 1160 IM IM tM HO A26 tM LOW it" 1f160 1990�1"W 1010 21P, Jo,, � 390 90 y Av~' 1��• i240 70 7i0 xdd 160 � rC Y� 14W 3% 147P LWD L9 2W 1P1U 1P]0 Changes in Irrigated Agriculture 1987=2018 1997 11994Tl9!991200-312-0051.200-7120091201-012-011 1201312ol412015 12o16 5-o1712olE Edna Valley Subarea (or-res) Citrus 12 6 47 =_S 51 51 53 49 105 105 111 111 191 1D= 111 DecIduous 0 0 0 13 0 0 C. 2 2 2 4 3 Pasture 138 1 19 19 J 19 1 19 A 19 t-S 1G 19 1 19 13 J 4 1 13 Vegetable. 533 703 685 686 646 699 663 579 647 .671 670 691 394 505 453 V i neys rd 1, 180 1+ 3" 1 ix!goD 2,2 52 2,297 2r37 7 2+ 377 2+ 37 2 2,3 90 2a 423 2.,419 2,419 2r454 2r415 2,323 Subtotal 1r 3 2-+0-7 2x651 3r00 3r 013 3r 146 3+11 3r 11'9 3+151 3a.215 3r2 2-1 3a 2-42 3,05613,129,3,0021 Development of a Water Budget .. • San Luis Subarea = +700 Acre-Feet/Year (Surplus) • Edna Valley Subarea = -1,100 Acre-Feet/Year (Deficit) A Summary of Existing Conditions • San Luis Subarea and Edna Valley Subarea have different water level conditions, one in surplus, the other in deficit. • Water levels within the Edna Valley continue to decline due to overpumping of groundwater, which appears to be linked to the increased volume of vineyard irrigation. • Actions taken within one subarea of the basin do not have a noticeable impact on the other subarea due to a bedrock divide between the two subareas. What is "Sustainable Groundwater Management"? The management and use of groundwater in a manner that can be maintained during the planning and implementation horizon (2022-2042) without causing Undesirable Results. Undesirable Results Chronic Lowering Groundwater Levels Degraded Water Quality Reduction of Storage Land Subsidence + + Surface Water Depletion How we Stop Undesirable Results 1. Establish a "Monitoring Network" • Groundwater Level Monitoring Groundwater Quality Monitoring Surface Water Flow Monitoring Monitoring Network Creation t _ - f � # t��f' rr� -L 'f• �+M SLY-06 s - LlY2 $-L5RY.71 -E-SLY•13 su`vi-.1SaLXU�.--1�-0 SY•17 siv-1LYA ----- a �SLV•79 !... l �: Z, LY,2 2 ma J r ♦` EVA3 EV-O-0 EV-05 1V . jr r'-p4{�E Y-07 EY-0 1r ! = r Explanation r� SLO Valley Groundwater ea9i6 Boundary j- --- Sonrea Boundary CRY Umils o Existing Well Site l Existing Well Site - Transducer Recommended tiRecommewd topddrtlonal ell Site r Representative Well1 by Creeria Measured Chrark Water Level decline Storage Decline Land Suhsidoncs ❑ Intercarrneded Surface Water Depletion V-f 1 tsV.i2 �1 'J ��� EV�15.�yEY•1-0 EY-1S 7 � €v.1e How we Stop Undesirable Results 2. Establish Minimum Thresholds and Measurable Objectives 300 250 200 a� 5❑ 0 191 -100 1990 RMS EV-12 (31S/13E-27MO3 ) L and Surface Elam non too-Mft FAT 172ft - -265#t Saturated TAkknm i }Observed ■ lms 5edroek Ett,�xafr [Mp+a■1 2000 2010 2020 2030 2040 CHRONIC LOMRING OF GROU ID1'ATER LEVELS REDUCTION OF GROUPIDWATER STORAGE t � �� r ti }J1 �w m 0 ds& H inabili .,Illllo A 414r" 1, M_ pit 01% "k!O once 01- _Ilvo 7RS,k%m (GSP Chapter 9) State Water Projects Projects and Implementation Annual Annual Total Quantity Unit Cost Management Status Timing Capital Cost Capital O&M Annual of Water (JAF)1 Actions Payment Payment (AF) Feasibility study 0 to SWP toAg Not begun 1years 890,000 58,000 $ 5,040 $ 63,000 1,000 S 60 Irrigation yet Design/Construction= Feasibilitystudy_ 0 SWP Recharge Not begun to 1 years $ 3,624,000 $ 236,000 $ 101,000 S 337,000 500 $ 670 yet Design/Construction: 1 to 5 years Feasibility study: 0 SWP to GSWC Not begun to 1 years $ 2,685,000 $ 175,000 $ 17,000 $ 192,000 200 $ 960 yet Design/Construction: 1 to 5 years Feasibility study: 0 SWP to Mutual Not begun to 1 years $ 835,000 $ 54,000 $5,000 $59,000 50 $ 1,180 Water Companies yet Design/Construction: 1 to 5 years Important Details: • Potable supply that could provide regional resiliency • Only project identified that can provide 1,100 AFY of water • Available for a long time period • Available quantities reduced by drought Volume Available: 1,000+ AF/Year Estimated Purchase Price of Water: $2,000 — $2,500/Acre-Foot Price Canyon (Sentinel Peak) Discharge Relocation Projects and I m p I e ni a ntation Annual Annual Tota I Qua ntiky Unit Cost Ma na ge nie nt Status Tinti i ng Capital Cost Capital �& M Annual of Water Actions Payment Paynient (AF) M itigated Feasib i I its+ study- 0 Price Canyon Discha rge N egati ire Dec to 1 years � 4,909,OM $ g19,0OC 56,DOO S 37 5, 00 0 500 z � 7� Reloca#ion Completed in a esig n/Construction 2C15 1 to g years Volume Available: 500 Acre-Feet/Year Estimated Purchase Price of Water: Unknown Important Details: • Dependent on the continued operation of the Sentinel Peak facility • Estimated benefit of 300 AF/Year to the basin • Per acre-foot pricing is to be negotiated City of SLO Recycled Water to Edna Valley Growers Projects and I m p l e ni a ntation Annual Annual Tota I Quantity Unit Cost Managenient Status Tiny rig Capital Cost Capital Annual of Water ($/AFJi Actions Payment Payment GAF) Evaluated as City of S LO part of the Fear i bility stud~{_ 0 too Recycled Water City of S LO 1 years $ '1,O04,O00 S 65,000 $ 88,NO 153,000 600 � � 260 Recycled a esig n/Cons;truction to Ag Irrigation plater Stud{ 1 to 0 years (2017) Volume Available: 500-800 Acre-Feet/Year Estimated Purchase Price of Water: $415100/Acre-Foot Important Details: 1. Not be used to increase development potential of property being served. 2. Not to be further treated to make it potable. 3. Area being served required to maintain conservation or open space easement 4. Must not impair the City's ability to serve City's build -out water demand needs. City of SLO Potable Water to Golden State Water Company Projects and Annual Tota I Quantity Implementation Annual Un it Cost Managenient Status Tintiing Capital Cost Capital �&f�1 Annual of Water {/AF�� Actions Payme nt Pair nient (AFC City of 3 LO Feasibility study_ 0 Pota b I e Wate r to Not begun to 1 years 1,73 9,00 0 $ 1-47r000 14r0-00 12 7,OD 200 640 yet Design/Construc4on- GLSWC 1 to S years Volume Requested: 200 Acre-Feet/Year Estimated Purchase Price of Water: $8,200/Acre-Foot (rate established at 2x City rate for existing outside -City users) Important Details: • Not permitted for delivery outside of City per General Plan Policy "The City shall not provide nor permit delivery of City potable water or sewer services to the following areas. However, the City will serve those parties having valid previous connections or contracts with the City. A. Outside the City limits; B. Outside the urban reserve line;" 1,000 ANY Pumping Reduction in Edna Subarea 2SO 225 200 175 150 125 100 Ell-13 N N N N N N Fi v r 0 m Management Actions Efficiency Improvements Voluntary Conservation Water Efficient Crop Selection Mandatory Pumping Reductions Implementation Plan G5P ImPleme Administrative and Finance GSPAdministration Develn rnent Deve lop Administrative AoachJGovema rice Structure for GSP implementation $100,000 Lump Sum 01-4,2022 $1w,Doo Ongoing GSP Implementation Routine GSP Administration (including staffing, overhead expenses, equipment, outreach and communication, etc.) $500,OD0 Annual 2021- 2025 $2,500,WO Fee Study Prepare a fee study to evaluate and provide recommendations for GSP implementation funding mechanisms $150,000 Lump Sum ql-4, 2022 $15D,DOo Funding Mechanism Implementation Implement and begin collecting GSP Im lernentation fees $100,OD0 Lurnp Sum CI1-4, 2021 $10D,DOo Demand Management Plan The demand management plan will include the documentation of water conservation measures, and develop programs for volunteer water efficient crop conversion, volunteer Fallowing of crops, and pumpingred uctions, etc. In a stakeholder driven process. $100,OD0 Lurrip Sum 2022 - 2021 $100,000 Monitoring Network Implementation Groundwater Metering and Reporting Plan Develop n planto establishand maintain agroundwater pumping, metering, and reporting plan (does not include meters and installation) S150,01M Lum Sum CLl-0, 2022 $15c'ma Conduct survey of proposed monitoring well network to verify Ocation5 and elevations, and video logging if applicable $100,000 Lump Sum ql-4, 2022 $10D,D00 Monitoring Program Construction of 5 new monitoring wells and 5 surface water gages for GDEs and GwJSw interaction, transducers and surveying $500,01V Lump Sum Q1-0, 2022 $5W MO Annual Monitoring Complete annual monitoring(Field work) $25,OD0 Annual q1-4, 2022 $125,D00 Project I m plementation Supplemental water Feasibility Study costs estimates for the Supplemental water Feasibility Study, Planning/Design and Construction of Supplemental water Projects not included intheinitial 5-Yrbudget. Planning/Design Construction Reorti fig Annual Reports Compile data and prepare GSP Annual Report $100,OW Annual 2021- 2025 $500,D00 5-Yr GSP updates Compile data and prepare Syr GSP updates, including Integrated Model updates $500,000 Lurnp Sum Q2, 2026-01, 2027 $500,D00 Total Estimated Costs (2022 - 2027) $4,925,000 Average ,annual Estimated Cost (2022 - 20271 $965,000 Next Steps • August 18, 2021 through September 18, 2021 - Complete draft GSP released for public comment/review. • September 7, 2021 - Return to City Council with Council Item outlining any significant changes to the GSP. • October 6, 2021 - Groundwater Sustainability Commission will vote on recommending GSP adoption to the City and County GSAs. • December 7, 2021 — Final GSP brought to City Council (City GSA) for final adoption. • January 31, 2022 — GSP Submitted to Department of Water Resources. Study Session Focus Areas 1. Does the City Council wish to continue with the existing governance structure, which includes a Groundwater Sustainability Commission that acts as an advisory body to the City and County GSAs, during the GSP implementation period (2022-2042)? CITY OF SLO GSA COUNTY OF SLO GSA EDN A VALLEY ROWERS M C AWN ORTIZ LEGG ANDY PEASE BOB SGHIEBELHUT Member Member Chair BR U E G IB ON AARON RLO D G FOR E D NATI Allernale Ahernale Alternate EDNA RANCH AND VARIAN RANCH I YY C DENNIS FERNANDEZ Member JAMES LOKEY Allernale • i Golden State ##*# �/!8llr �8rri Q8Hy MARKZIMMER Vice Chair TOBY Iw OORE A flernale Study Session Focus Areas I AmoMi� 2. Does the City Council support staff's recommendation that GSP implementation costs including the costs to construct projects, should be borne by those benefitting from the project(s) or action(s) and that the City should only be responsible for its proportional share of GSP implementation costs? 3. Does the City Council support the inclusion of a project to sell City Recycled Water to the Edna Valley Growers within the GSP, in alignment with existing General Plan policies? Study Session Focus Areas I AMON116-V 4. Does the City Council support staff's request for the removal of the Potable Water Sales to Golden State Water Company project from the GSP due to direct conflict with existing General Plan policies regarding outside -city potable water sales? 5. Does the City Council support staff's recommendation to include all State Water -related Projects to the Enda Valley subarea and the Sentinel Peak Discharge Relocation Project within the GSP? 6. What other comments does the Council want to provide on the GSP? Questions? City of San Luis Obispo Current Reservoir Capacity Historical Average July % Capacity 15,163.7 acre-feet 29,555.4 acre-feet 68,370.0 acre-feet Salinas Whale Rock Updated: Wednesday, July 14, 2021 Nacimiento Table 6-2: FlistoricaI Water Budget - Edna Valley Subarea. SURFACE WATER INFLOW (AF) SURFACE WATER OUTFLOW (AF) GROUNDWATER INFLOW (AF) GROUNDWATER OUTFLOW (AF) a= 4 d _CL 4 = A 3 C E N 4 = u�i a5� a c fl W Q s„�i c 2� a w = d .N c Q 'J a IC K Q v A 9 <C = Vj Y V $ p G � F C1 J 4 � F �p i+ ±! � = 4! 2 � ^J �� Y a Q �� = j 4 � C 3 J O = y N 6 Y c W ap Ln �. 2 > 7 C r Q J = 4 KEY A B B C F F F F I 1 J K L I 1 J K m B B O P, 1987 6,780 8,860 6,900 5,960 8,300 630 760 640 740 760 2,450 2,75C 2,670 3,040 2,810 2,150 3,240 1,210 730 1,940 12,010 15,610 11,420 10,470 13,810 6,610 7,970 6,670 5,960 7,550 450 560 470 530 530 2,000 2,240 2,190 2,490 2,300 40 40 20 20 20 140 660 180 90 570 190 210 180 220 240 440 510 490 550 510 30C 45C 170 100 270 1,840 2,960 1,070 620 10840 12,010 15,600 11,430 10,480 13,830 140 660 190 9C 570 190 210 180 220 240 44C 510 420 SSC 510 300 450 170 100 270 110 110 110 110 110 1,180 1,940 1,120 1,070 1,700 630 760 640 = 760 2,450 2,750 2,670 3,040 2,810 100 100 100 100 100 3,180 3,610 3,410 3,880 3,670 -2,000 -1,670 -2,290 -2,810 -1,970 1988 1989 1990 1991 1992 90880 13,780 7,S70 14,870 10,310 790 &W 760 820 SSO 2,810 2,710 2,640 2,820 3,000 30770 S,810 2,S60 5,930 %990 17,2S0 23,140 13,S30 27,440 19,150 2,030 8,000 7,050 7,930 7,980 530 570 500 550 550 2,300 2,220 2,170 2,320 2,470 40 40 40 40 40 1,460 4,800 400 5,740 1,920 270 290 270 280 310 S10 490 470 500 S30 S30 810 360 1,250 560 30590 50940 2,280 80840 %900 17,260 23,160 13,540 27,450 1.8,160 10460 4,800 400 5,740 1,920 270 290 270 280 310 S10 49C 470 S00 530 S30 810 360 1,250 560 110 110 110 110 110 2,980 6,500 1,610 7,880 3,430 790 840 760 820 850 2,810 2,710 2,640 2,820 3,000 100 100 100 100 100 3,700 3,650 3,500 3,740 3,950 -220 2,850 -1,890 4,140 -520 1993 1994 1995 1996 1997 13,,390 14,870 7,620 11,060 10,950 1,030 S60 1,020 940 920 3,460 3,000 3,720 2,700 3,320 5,910 %730 2,590 4,400 4,330 24,390 28,460 14,950 19,120 19,580 7,840 7,790 6,990 7,710 7,670 690 570 690 600 630 2,850 2,480 3,070 2,230 2,750 40 40 40 40 40 5,010 5,750 470 2,650 2,S50 350 300 340 350 360 610 520 650 480 570 830 1,360 360 62C 610 6,190 9,660 2,340 40470 40400 24,410 28,470 14,950 19,1SO 19,580 SO= %750 470 2,650 2,550 350 300 340 350 360 610 52C 650 48C 570 83o 1,360 360 620 610 110 110 110 110 110 6,910 8,040 1,930 4,210 4,200 10030 860 1,020 940 980 3,460 3,000 3,720 2,700 3,320 100 100 100 100 100 4,590 3,960 4,840 3,740 4,400 2,320 4,080 -2,910 470 -200 1999 1999 2000 2001 2002 6,600 10,220 7,SS0 13,280 11,570 960 970 970 840 900 3,220 3,030 3,040 2,870 3,040 2,060 %950 2,340 S,540 2,180 12,840 19,070 13,500 22,530 17,690 6,400 7,600 6,740 7,610 7,580 630 570 630 550 S90 2,660 2,500 2,520 2,370 2,520 40 40 40 40 40 170 2,100 320 4,450 3,100 340 320 350 300 320 570 520 530 S00 530 290 SSC 330 78C 31C 1,760 %970 2,070 5,930 2,730 12,860 18,070 13,530 22,530 17,720 170 2,000 320 40450 3,100 340 320 350 300 320 570 52C 530 S00 53C 290 550 330 780 310 110 110 110 110 110 1,480 3,500 1,640 6,140 4,370 960 870 970 S40 900 3,220 3,030 3,040 2,870 3,040 100 100 100 100 100 4,280 4,000 4,110 3,810 4,040 -2,800 -500 2,470 2,330 330 2` 2004 21105 2 2007 3,810 6,SS0 5,170 10,S20 14,870 1,180 1,210 950 820 840 3,830 3,750 3,650 3,360 3,330 20160 %750 2,740 70490 7,840 1.0,980 15,560 12,520 22,190 26,880 3,800 6,580 5,100 7,S60 7,550 770 780 650 550 580 3,170 3,100 3,040 2,790 2,760 40 40 40 40 40 0 220 50 2,260 5,760 430 440 310 270 270 660 650 620 S70 570 300 520 380 1,0S0 1,100 1,820 3,230 2,330 70100 8,260 10,990 15,560 12,520 22,190 26,890 0 220 50 2,260 5,760 430 440 310 270 270 660 650 620 570 570 300 S20 380 1,050 1,100 110 110 110 110 110 1,500 1,940 1,470 4,260 7,810 10180 1,210 950 820 840 3,830 3,750 3,660 3,360 3,330 100 100 100 100 100 5,110 5,060 4,710 4,280 4,270 -3,610 -3,120 -3,240 -20 3,540 2008 2009 2010 2011 2012 7,440 40640 4,590 50230 S,920 940 1,040 960 880 790 3,560 3,780 3,580 4,230 3,200 1,810 10260 1,120 490 1,560 13,750 1.0,720 10,250 1.0,930 14,470 6,930 4,600 4,550 5,160 7,550 650 740 680 650 580 2,950 3,120 2,960 3,S00 2,680 40 20 20 20 40 450 40 30 60 980 290 310 280 230 220 610 666 620 720 530 250 ISO 160 70 22C 1,660 10070 950 410 1,680 13,730 10,740 10,250 10,820 14,490 4S0 40 30 60 980 290 310 280 230 220 610 660 620 720 530 250 180 160 70 220 110 110 110 110 110 1,710 1,300 1,200 1,190 2,060 94o 1,040 960 880 790 3,560 3,780 3,580 4,230 3,200 100 100 100 100 100 4,600 4,920 4,640 5,210 4,090 -2,890 -3,620 -3,440 -4,020 -2,030 2013 2014 2015 2016 2017 14,870 6,130 13,210 SSO 880 770 3,640 3,SS0 3,350 6,240 6S0 5,480 25,600 11,210 22,810 7,570 6,020 7,630 640 650 580 3,030 2,960 2,500 40 40 44 5,730 90 4,37D 220 240 210 610 S90 550 870 90 77C 6,890 540 5,870 25,600 11,220 22,820 S,730 90 4,37D 220 244 210 610 590 550 970 90 770 110 110 110 7,540 1,120 6,010 850 880 770 3,640 3,S50 3,350 100 100 100 4,590 4,530 4,220 2,950 -3,410 1,790 2018 2019 Type Year ary f j f Wet AF = Atre-Feet; KEY = Referenced Component! on Figure &3 Table 6-1: Historical Water BudYet - San Luis Valley Subarea. SURFACE WATER INFLOW (AF) SURFACE WATER OUTFLOW [AF] GROUNDWATER INFLOW (AF) GROUNDWATER OUTFLOW (AF) 3 ._9 N 2 a N .z 4 4 E. 3 y •n 0 Q n a" a a 3 O wa 4 �a m d �� - a AA n d c - 3 o p E N r 4 a ~p ~ o z S a za V a� a d 7 s ;, & car - V A a� a d ° &i c - p 3 t7 q z t m a 2 C o f N r � N 4 W c n 3 t 4 m O r 7 T L7 c a a A z w KEY A B B C D E F F F FIG H 1 J J K L I J J K M B B N O P 1987 7,720 10,080 7,850 6,790 9,450 410 430 660 2,180 2,350 1,30Q 1,750 1,580 1,850 1,790 6,410 9,660 3,600 2,140 5,790 5,520 5,320 4,070 1,970 2,520 8,490 9,190 6,020 1,280 1,960 29,850 35,420 23,780 16,210 23,86C 7,450 8,540 7,550 6,660 8,250 2,850 2,780 2,180 1,200 1,460 1,050 1,410 1,270 1,490 1,440 740 790 390 410 390 5,520 5,320 4,070 1,970 2,520 220 1,26Q 250 110 MO 530 520 430 29Q 320 260 350 310 370 350 1,090 1,640 610 360 980 10,150 12,840 6,730 3,360 7,160 29,860 35,440 23,780 16,220 23,840 220 1,260 250 110 980 530 520 430 290 320 260 350 310 370 350 1,090 1,640 610 360 980 340 340 340 340 340 2,440 4,110 1,940 1,470 2,970 410 430 660 2,180 2,350 1,30Q 1,750 1,590 1,850 1,790 1,050 1,320 1,130 1,250 1,190 120 120 120 120 120 2,880 3,620I 3,490 5,400 5,450 A40 490 I-1,550 I-3,930 -2,480 1998 1989 1990 1991 1992 11,250 15,700 9,620 16,930 11,740 2,240 1,030 790 660 740 1,820 1,790 1,690 1,970 1,910 11,250 17,350 7,640 26,690 11,930 3,070 3,630 3,750 3,780 4,210 2,910 4,980 5,400 5,590 6,160 32,540 44,480 27,89C 55,520 36,690 8,590 8,640 7,900 8,630 8,530 1,720 1,980 2,030 2,060 2,250 1,460 1,440 1,360 1,500 1,530 70Q 660 740 540 680 3,070 3,630 3,750 3,780 4,210 2,200 5,9SQ SSQ 6,070 1,820 360 400 410 410 44Q 360 350 330 370 380 1,910 1,210 1,30Q 1,870 830 12,160 20,210 9,480 30,300 16,010 32,530 44,470 27,880 55,530 36,680 2,200 S,950 580 6,070 1,820 360 400 410 410 440 360 350 330 370 380 1,910 1,210 1,300 1,870 830 340 340 340 340 340 5,170 8,250 2,960 9,060 3,810 2,240 1,030 790 660 740 1,820 1,790 1,690 1,870 1,910 1,090 1,190 1,090 1,110 1,040 120 120 120 120 120 5,270 4,130 3,690I 3,760I 3,810 -100 4,120 -730 5,300 0 1993 1994 1995 1996 1997 15,930 16,930 9,670 12,620 12,470 790 690 660 670 710 2,290 1,870 2,510 1,810 1,740 17,670 26,460 7,720 13,130 12,920 4,400 4,150 4,350 4,410 4,250 6,440 6,130 6,470 6,550 6,270 47,500 56,220 30,380 39,200 38,360 8,580 8,580 7,870 8,530 8,570 2,370 2,230 2,340 2,350 2,290 1,930 1,5W 2,020 1,450 1,400 690 520 810 670 67Q 4,400 4,150 4,350 4,410 4,25Q 2,690 1,770 650 2,950 1,59Q 460 440 450 450 44Q 450 370 500 360 34Q 530 790 1,310 920 9DQ 25,510 35,980 10,100 17,090 17,900 47,510 56,230 30,400 39,190 38,350 2,690 1,770 650 2,950 1,590 460 440 450 450 440 450 370 SOO 360 340 530 790 1,310 920 900 340 340 340 340 340 4,470 3,710 3,250 5,020 3,61Q 780 690 660 670 710 2,280 1,870 2,510 1,810 1,74Q 1,290 1,040 1,330 1,040 1,040 120 120 120 120 12Q 4,470 3,710I 4,620 3,640 3,610 0 0 -1,370 1,380 Q 19" 1999 2000 2001 2002 7,510 11,630 9,140 15,120 13,180 690 61D 620 620 610 1,850 1,470 1,SOQ 1,370 1,2R0 6,130 11,790 6,990 16,560 6,S00 4,530 4,610 4,340 S,390 4,950 6,340 6,300 6,740 6,2SO 6,220 26,990 36,400 22,330 4S,310 32,200 7,240 8,640 7,780 8,720 8,710 2,000 1,860 2,560 1,040 1,S00 1,490 1,120 1,200 1,100 1,030 770 690 76Q 60D 660 4,530 4,610 4,340 5,390 4,9SO 220 2,490 300 1,RSO 1,580 440 440 460 440 440 360 290 290 270 250 1,040 82Q 1,190 1,160 450 8,900 15,390 9,450 24,730 13,220 26,990 36,400 28,330 45,300 32,790 220 2,490 300 1,250 1,S80 440 440 460 440 440 360 290 290 270 250 1,040 220 1,190 1,160 450 340 340 340 340 340 2,400 4,380 2,S80 4,060 3,060 630 610 620 620 61O 1,950 1,470 1,50Q 1,370 1,290 1,140 1,040 1,140 950 1,050 120 120 120 120 120 3,740 3,240 3,380 3,060 9,060 -1,340 11,140 -am 1,000 0 2003 2064 2005 2 2007 4,340 7,800 5,890 11,980 1 16,930 610 520 560 Sao 530 1,510 1,550 1,430 1,160 1 1,260 6,140 11,030 7,670 22,860 1 21,360 4,200 4,010 3,930 4,160 4,480 6,840 6,730 6,580 5,860 1 5,530 23,640 31,640 26,060 46,600 50,090 4,330 7,540 5,940 8,680 1.8,750 2,770 2,770 2,740 1,850 1,170 1,210 1,250 1,150 940 1 1,020 840 790 790 650 630 4,200 4,010 3,930 4,160 4,480 O 210 40 2,590 1,400 480 470 490 450 430 290 30Q 280 220 240 1,040 1,870 1,300 1,600 640 2,440 12,410 9,500 25,460 31,350 23,600 31,620 26,050 46,600 50,090 0 210 40 2,590 1,400 480 470 480 450 430 290 300 280 220 240 1,040 1,870 1,300 1,600 640 340 340 340 340 340 2,150 3,190 2,440 5,200 3,050 61O 520 560 580 530 1,510 1,550 1,430 1,160 1,260 1,250 1,260 1,140 960 1,150 120 120 120 120 120 9,490 3,450I 3,250I 2,820 3,060 -1,340 -260 -810 12,380 -10 20o8 2009 2010 2011 2012 9,470 5,290 5,220 5,960 10,150 530 510 540 400 400 1,420 1,790 1,560 1,680 1,690 5,430 3,670 3,270 1,620 4,850 3,950 4,060 3,660 3,420 3,550 5,770 6,330 6,190 5,750 5,490 25,570 21,650 20,440 18,830 26,130 7,940 5,260 5,190 5,900 8,490 1,910 2,320 2,620 2,300 1,920 1,150 1,450 1,260 1,360 1,360 770 430 420 410 730 3,950 4,060 3,660 3,420 3,550 430 30 20 50 1,350 450 470 470 440 430 270 340 30Q 330 330 920 620 560 270 820 7,770 6,670 5,940 4,340 7,130 25,560 21,650 20,440 19,820 26,110 430 30 20 50 1,350 450 470 470 440 430 270 340 300 330 330 920 620 560 270 820 340 340 340 340 340 2,410 1,800 1,690 1,430 3,270 530 510 540 40Q 40Q 1,420 1,790 1,560 1,690 1,690 1,200 1,350 1,290 1,270 1,170 120 120 120 120 120 3,270 3,770 3,510 3,470 3,380 -860 -1,970 -1,920 I -2,DW -110 2013 2014 2015 2016 2017 16,930 6,980 15,040 400 400 400 1,550 1,190 1,030 18,450 2,630 16,360 4,400 3,330 4,360 5,370 5,790 5,080 47,100 20,320 42,270 8,730 6,870 8,800 960 2,430 720 1,250 970 930 590 80Q 630 4,400 3,330 4,360 6,910 90 4,430 440 450 420 30Q 230 200 550 190 490 22,970 4,970 21,400 47,100 20,320 42,280 6,910 90 4,430 440 450 420 300 230 200 550 180 490 340 340 340 8,540 1,290 5,880 400 400 400 1,550 1,190 1,030 1,260 1,270 1,070 120 120 120 3,330 2,980 2,620 5,210 -1,69D 3,260 12018 2019 Type Year Dry Above N j Wet AF = Acre -Fee[; KEY = Referenced Components on Figure 6.3 IE so 40 20 10 Historical Precipitation - Cal Poly Rain Gage +Rainfall (in) Overall Average Rainfall —Cumulative Departure From Mean Rainfall Type of Rainfall Year. 0 Dry Below Normal 0 Above Normal 0 Wet DRY WET AVERAGE DRY WET DRY II'I.�ieMrL�lli� r I&IMI,''"y Q- IM 199E 20M 2015 Water Year Figure 6-10; 1987-2019 Historical Base Period Climate. ISO 100 c c s0 26 0 E v -s0 -100 1 l i i r rE, rJ FXplanation SLa Valley Groundwater ti4 j Basin Boundary Subarea Boundary Irrigated Crop Types +.,. �] Citrus Deciduous Pasture Vineyard _ y i Ow r �y 1 PrrM:+�v�rFo�: rt.r.r.nc.■; r,•��+•.. San Luis Obispo Valiey Basin rrrigted Craps a�eie Svbem aen F.er CAm...: =F%I6 Feel 2016 .. ,w•« ,.. � ., .. , , .., � avgeaov �mtstc�e�co,v f Y i�'ili(1W � "� 9 Hmmoaai Ginn. WLfl9 + ytmca G n = u a eev ni e wr-v seKe $AN wIS O&-& O vAi LE &4$t4 asp; r•ex� Figure 6-12 rhu W