HomeMy WebLinkAboutItem 7a. Receive an Update on the Recycled Water Maximization Study Item 7a
Department: Utilities
Cost Center: 601 – Water Fund
For Agenda of: 11/15/2022
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 RECYCLED WATER
MAXIMIZATION STUDY
RECOMMENDATION
Receive an update on the Recycled Water Maximization Study and provide input
regarding the future expanded use of the City’s recycled water supplies.
POLICY CONTEXT
As part of the 2021-23 Financial Plan the City Council approved funding to study the
maximization of the City’s use of its recycled water supplies. The 2022 Recycled Water
Maximization Study provides opportunities for short-term and long-term expansion of
recycled water supplies in alignment with the funding and direction provided by the City
Council.
DISCUSSION
Background
Recycled water was first used in California in 1930 and is now widely utilized as an
additional water supply by many medium and large water utilities. Historically, recycled
water has been utilized for landscape irrigation to offset potable water use ; however,
recent changes to regulations and treatment technologies are providing a greater
opportunity to utilize recycled water to augment drinking water supplies . As the City
continues to mitigate climate change impacts and bolster its water security, staff have
drafted the Recycled Water Maximization Study (2022 RWMS, Attachment A), which
provides detailed information that will be critical in maximizing the use of the City’s
recycled water supplies. The 2022 RWMS supplements this staff report by providing
background information on the City’s recycled water program, explaining recent changes
to recycled water availability, identifying short-term and long-term projects to maximize
recycled water use, and identifying the legal risks, policy considerations, pricing
strategies, and delivery constraints that must be considered if recycled water were to be
delivered outside of City limits.
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How to Use the 2022 RWMS
This staff report provides a summary of major discussion points of the 2022 RWMS. This
staff report is intended to be supplemented by the 2022 RWMS, which contains additional
detail related to long-term and short-term recycled water projects, as well as details about
project costs, benefits, and challenges. Where possible, this staff report refere nces the
page numbers of the 2022 RWMS that contain additional detail about a specific topic of
discussion.
Current City Use of Recycled Water
Traditionally, recycled water has been used in California for non -potable uses such as
landscape irrigation, agricultural irrigation, environmental restoration, and construction
use. W ithin the City, the established use of recycled water primarily goes toward
landscape irrigation, utilization to supplement creek flow in San Luis Obispo Creek to
support creek habitat, and for short term use at large construction sites for dust control,
grading, and compaction. Recycled water is not used for agricultural irrigation within the
City because agricultural operations have overlying groundwater rights which are less
expensive than purchasing the City’s recycled water. The City’s recycled water supplies
are not currently permitted to be utilized for groundwater recharge or surface water
augmentation.
Expanded Uses of Recycled Water
Recent changes in regulations
and technological capabilities
have increased the potential
uses for recycled water, which
could substantially increase
recycled water use in the
future. In 2014 the State of
California adopted
groundwater recharge
regulations, permitting the use
of recycled water for recharge
of groundwater basins for use
later as drinking water supplies. In 2018 the State adopted regulations permitting recycled
water to be utilized to augment surface water reservoirs for future extraction and potable
use.
Both expanded uses, often referred to collectively as Indirect Potable Reuse (IPR),
require additional treatment beyond what is required of recycled water that is utilized for
irrigation use. This expanded treatment, known as advanced treatment, is designed to
ensure that recycled water is safe for human consumption when paired with an
environmental buffer such as a surface water reservoir or groundwater basin. The City
does not currently produce advanced treated recycled water; however, many of the
technologies integrated into recent upgrades at the Water Resource Recovery Facility
(WRRF) leave the City well positioned to treat recycled water to this standard in the future.
Short Term RW Uses
as Non-Potable Water
(2022-2030)
•Expansion of Inside-
City Irrigation Use
•In-City Agricultural
Pumping Offset
•Outside City Delivery
for Agricultural Use
Long Term RW Uses
as Potable Water
(2030+)
•Groundwater
Replenishment
•Surface Water
Augmentation
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Long-Term Recycled Water Maximization Strategies
To date, the City is unable to completely utilize its recycled water supplies due to
infrastructure limitations that restrict delivery, and due to the misalignment of periods
when recycled water is produced versus when it is needed for irrigation use. In an effort
to fully utilize its recycled water resources, the City’s 2017 Recycled Water Master Plan
(RWMP) identified Indirect Potable Reuse as a feasible strategy to put recycled water to
its highest and best use.
Following the adopted strategy to pursue potable reuse outlined in the 2017 RWMP, in
2022 the City contracted with Carrollo Engineering to identify the feasibility of
implementing a groundwater recharge or surface water augmentation project . While
currently in draft form, this plan examines the regulatory requirements and feasible
construction timelines for implementation of indirect potable reuse projects. Importantly,
this study documents that the City could have a project constructed and operational within
eight years if it focused efforts on this expansion strategy. Knowing that there is a time
period of at least eight years before the City can fully utilize recycled water as a drinking
water supply, the 2022 RWMS identifies opportunities for short-term recycled water
supply maximization until a potable reuse project is implemented in the City.
Short-Term Recycled Water Maximization Strategies
Until the City carries forward a project for groundwater recharge or surface water
augmentation of recycled water, three primary opportunities exist for the short-term use
of recycled water. These short-term uses vary in complexity, cost, and benefit to the City’s
water rate payer. Details of each project type are documented below.
1. Expansion of In-City Recycled Water Irrigation (2022 RWMS, Page 16)
This project would maintain the City’s existing short-term expansion plan, focusing
efforts on increasing the use of recycled water for irrigation of local parks, business
parks, and residential common areas. The City is already permitted for this type of use
of recycled water and has staff dedicated to fulfilling these duties. The City has made
investments in installing delivery pipelines throughout the southern side of the City,
allowing expansion of recycled water to new sites to be more cost-effective than it was
during the early years of the recycled water program. Many sites that could be cost -
effectively converted to use recycled water are identified within the 2017 RWMP.
2. Agricultural Offset within City’s Area of Groundwater Basin (2022 RW MS, Pages 16-17)
While the SLO Valley Basin GSP largely focused on over-pumping in the Edna Valley
Subarea of the groundwater basin, significant agricultural groundwater pumping is
also conducted in the San Luis Subarea. From 2016-2019 agricultural pumping in the
San Luis Subarea was approximately 1,370 acre-feet per year. Several agricultural
operations in the subarea are adjacent to existing recycled water pipelines and can
utilize recycled water with minimal infrastructure investment. This project would
consider the delivery of recycled water to agricultural operations within the San Luis
Valley Subarea in exchange for an equivalent reduction in groundwater pumping by
these parties. This reduction in groundwater pumping by agricultural operations could
free up water within the groundwater basin for expanded domestic use by the City.
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3. Contractual Sale Outside of City Limits (2022 RWMS, Pages 17-27)
This project considers the short-term sale of the City’s recycled water supplies outside
of the City limits. With current City policy restricting the outside-City delivery of
recycled water to use for agricultural irrigation, this project could include delivery to
the Edna Valley, the Los Osos Valley, Cal Poly1, or to agricultural areas within the San
Luis Subarea, but outside of City limits, such as areas along Buckley Road, South
Higuera, and Los Osos Valley Road.
Outside City Delivery Considerations
The delivery of recycled water outside of City limits has a variety of constraints, risks, and
policy considerations that must be examined before entering into a delivery agreement.
Pages 17-27 of the Recycled Water Maximization Study (Attachment A) provide a
detailed analysis of these considerations, which should be reviewed in full. This staff
report provides a cursory overview of some of these constraints, risks, and policy
considerations that should be considered prior to delivering recycled water outside of City
limits.
1. Legal Considerations: Most legal concerns related to the delivery of recycled
water outside of City limits can be alleviated through a legal contract. However,
legal counsel advised that the City should ensure that the delivery of recycled
water outside of the City limits not result in the creation of habitat through the
reestablishment of surface water/groundwater interconnectivity, especially in
SGMA-regulated groundwater basins that are intending to utilize recycled water to
raise groundwater levels in order to achieve SGMA compliance. The
reestablishment of habitat resulting from recycled water offsetting groundwater
pumping could result in the permanent loss of recycled water supplies through third
party litigation requiring the City to perpetually maintain the established habitat .
2. Outside City Delivery Limitations: If entering into a contract to sell recycled
water outside of City limits, receiving parties should be aware that the City will likely
have reduced volumes of recycled water available in the future, as well as the
seasonal constraints that will prohibit delivery during the summer months. It should
also be considered at delivery outside of City limits is restricted by pipeline
capacity, and in many cases not economically feasible to increase beyond existing
capacity without significant capital expenditures. Potential may exist to deliver to
multiple outside City customers in order to maximize recycled water use.
3. Pricing/Cost Considerations: If electing to sell recycled water outside of the City
limits, special consideration must be mad e to compliance with Proposition 218.
Proposition 218 ensures that a customer’s water rates do not exceed their
proportional share of the costs for delivery of water services, meaning that any
contract for sale of recycled water outside of City limits could not adversely impact
1 It should be noted that Cal Poly recently issued a Notice of Preparation (NOP) indicating the potential
study of siting and building a Wastewater treatment Plant on the Cal Poly campus. If constructed, it is
unknow how this facility would impact City wastewater flows (daily, monthly, yearly) and thus reduce the
currently forecasted available recycled wastewater amount of 800 AFY.
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the City’s water rate payers. The 2022 RWMS provides three opportunities for
pricing of recycled water that staff believe would ensure proposition 218
compliance. These three pricing options provide varying degree s of parity between
inside City customers and outside City customers, accompanied by varying
degrees of benefit to the City’s water rate payers.
4. Policy Considerations: Outside City delivery of recycled water must comply with
the City’s General Plan policies. In summary, these policies would require that the
City’s recycled water only be delivered for agricultural use, that the water not be
utilized to increase the development potential of the property being served , and
that full costs for delivery are recovered. When considering the sale of recycled
water outside of City limits, staff do not believe that the City’s existing policies
would permit delivery in areas around the City that are subject to the San Luis
Obispo Valley Groundwater Sustainability Plan due to the fact that this water could
be used to free up groundwater for additional development/growth. In order to gain
compliance with requirements to not be growth inducing, policies would need to be
adopted by the County of San Luis Obispo, and infrastructure installed to track
groundwater pumping on a parcel-by-parcel basis and to restrict expansion of
groundwater pumping within the overdrafted areas of San Luis Obispo Valley
Groundwater Basin. Without this tracking and restriction, recycled wate r imported
into the basin would free up groundwater that could subsequently be pumped and
used for development or expansion.
STUDY SESSION FRAMEWORK FOR FEEDBACK TO STAFF
At this study session the City Council will receive a summary presentation of this r eport
and the 2022 RWMS, provide an opportunity for input from the public, and provide
questions and feedback to staff to guide the City’s strategy on how to best utilize recycled
water in the future. Below are a series of questions that the City Council may opt to use
to guide this discussion.
Long Term Strategy: Groundwater Recharge Utilizing Recycled Water
1a. Does the City Council support the long-term strategy of utilizing recycled water
to supplement the City’s groundwater supplies, as identified in the City Council
adopted 2017 RWMP?
1b. If not, please provide direction on alternative long-term maximization strategy.
Short Term Strategy (next eight years): Prioritization of Short-Term Projects
2. If yes to continuation of existing long-term strategy (1a), please prioritize options
A, B, and C (below) for short-term recycled water maximization.
A. Inside-City recycled water expansion for irrigation use (current strategy).
B. Exchange recycled water for reduction in groundwater pumping in the
City’s subarea of the groundwater basin.
C. Sell recycled water outside of City limits.
D. A combination or all of the above.
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Short Term Strategy Questions: Funding Requests
3. Would the City Council like to continue to expand recycled water irrigation within
the City at historical funding levels2?
4. Would the City Council like staff to include funding for staffing resources,
consultant services, and other new costs for new short-term strategies (B, C) in
the 2023-25 Financial Plan?
5. If the City Council recommends requesting new budget in the 2023-25 Financial
Plan to pursue outside-City sales of recycled water, what pricing strategy would
the Council support for sale of surplus recycled supplies?3
D. Sale at existing in-City Rates (90% of potable price).
E. Variable increases, plus flat costs (electricity, chemicals, wear and tear
on equipment, plus direct staffing and operating costs associated with
outside-City delivery).
F. Proportional share of all recycled water expenses based on per acre-foot
use, including sunk capital costs.
Previous Council or Advisory Body Action
On March 21, 2017, the City Council approved the 2017 RWMP which outlined the City’s
expansion strategy for recycled water use, including plans to ultimately utilize recycled
water as a potable water supply for the community.
Public Engagement
City staff have been in continued discussions with parties outside of City limits that are
interested in short-term contractual sales of the City’s recycled water. These discussions
largely took place during the drafting of the City’s Groundwater Sustainability Plan, as the
Edna Valley Growers Mutual Water Company was pursuing recycled water to offset
groundwater pumping for agricultural use. The City’s current strategy for existing recycled
water supplies, as well as discussions on available short-term supplies was discussed at
several public Groundwater Sustainability Commission (GSC) meetings between 2019
and 2021.
CONCURRENCE
The City’s Community Services Group (CSG) concur with the feasibility of the recycled
water maximization options provided in this report.
2 Recycled water expansion projects average around $400,000 per year, or 1.6% of the City’s water fund
budget.
3 Pricing strategies for outside-City recycled water sales can be reviewed in detail on pages 23-24 of the
2022 RWMS (Attachment A)
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ENVIRONMENTAL REVIEW
Receiving an update and providing input regarding the opportunities to maximize recycled
water use does not constitute a “Project” under State CEQA Guidelines Sec. 15378.
Depending on the expansion strategies recommended by the City Council, CEQA may
be required for future expansion projects. Projects will be analyzed on a case -by-case
basis to determine environmental review requirements.
FISCAL IMPACT
Budgeted: Yes/No Budget Year: 2021-23
Funding Identified: Yes/No
Fiscal Analysis:
Direction on recycled water maximization provided by the City Council does not in itself
result in a fiscal impact. If direction is provided to examine additional short-term expansion
projects, staff will return to the City Council with cost assumptions and funding requests
to support such work as part of the 2023-25 Financial Plan.
ALTERNATIVES
The City Council could request that staff examine other alternatives for
maximization of the City’s recycled water supplies. This action is not recommended,
as staff believe that the proposed options are legal, feasible, and could be implemented
in order to maximize the use of recycled water supplies.
ATTACHMENTS
A - 2022 Recycled Water Maximization Study
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2022 Recycled Water Maximization Study
City of San Luis Obispo Utility Department
October 2022
Ultraviolet Treatment at the Water Resource Recovery Facility.
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Table of Contents
I. Introduction ...............................................................................................................................6
II. Recycled Water Background Information ....................................................................................6
Currently Approved Uses of the City’s Recycled Water............................................................................ 7
Potential Future Uses of the City’s Recycled Water ................................................................................. 7
III. How Much Recycled Water is Available for Use? ......................................................................8
Changed Conditions Since 2006 ................................................................................................................ 8
Decrease in Recycled Water Supply ...................................................................................................... 9
Increase in Recycled Water Use ............................................................................................................ 9
Creek Discharge Requirement Modifications ....................................................................................... 9
Anticipated Changes to Recycled Water Availability and Demand ........................................................ 10
Increased Water Conservation Regulations ........................................................................................ 10
Expansion of Recycled Water Irrigation .............................................................................................. 10
Cal Poly Wastewater Reclamation Facility Construction / Master Plan Expansion ............................ 10
Sustainable Groundwater Management Plan (SGMA) Impacts .......................................................... 11
IV. Short Term vs. Long Term Maximization Strategy .................................................................. 12
Long-Term Recycled Water Use .............................................................................................................. 12
Groundwater Recharge Projects ......................................................................................................... 12
Surface Water Augmentation Projects ............................................................................................... 14
Short-Term Recycled Water Use ............................................................................................................. 15
Expansion of In-City Recycled Water Irrigation .................................................................................. 16
Agricultural Offset within City’s Area of Groundwater Basin ............................................................. 16
Contractual Sale Outside of City Limits ............................................................................................... 17
V. Outside-City Delivery Considerations ........................................................................................ 17
Legal Considerations ............................................................................................................................... 17
Outside-City Delivery Limitations ........................................................................................................... 19
Availability Limitations ........................................................................................................................ 19
Infrastructure Limitations ................................................................................................................... 20
Pricing/Cost Considerations .................................................................................................................... 20
Outside-City Pricing Options ............................................................................................................... 23
Policy Considerations .............................................................................................................................. 24
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VI. Conclusion ............................................................................................................................ 26
Tables
Table 1 - Wastewater Influent (Three-Year Intervals) .................................................................................. 9
Table 2 - Recycled Water Demand (Three-Year Intervals) ............................................................................ 9
Table 3 - Calendar Year 2022 Recycled Water Availability (in Acre-Feet Per Year) .................................... 19
Table 4 - Outside-City Recycled Delivery Pipeline Capacity ........................................................................ 20
Table 5 - Recycled Water Cost Categories .................................................................................................. 23
Terminology
Acre-Feet Per Year (AFY): One acre-foot of water is the volume that would cover one acre of land with a
food of water. This volume is equal to 325,851 gallons. AFY is often utilized to quantify bulk water volumes.
There are approximately three acre-feet per every million gallons.
Agronomic Irrigation Rate: The rate of application of recycled/reclaimed water and associated nutrients
to plants that is necessary to satisfy the plants' nutritional and watering requirements while strictly
minimizing the amount of nutrients that run off to surface waters or which pass below the root zone of
the plants.
Direct Potable Reuse: The planned introduction of recycled water either directly into a public water
system, as defined in Section 116275 of the Health and Safety Code, or into a raw water supply
immediately upstream of a water treatment plant.
Groundwater Banking: The process of diverting surface water or recycled water into an aquifer where it
can be stored until it is needed later.
Groundwater Recharge: The practice of increasing the amount of water that enters a groundwater aquifer
through human-controlled means.
Indirect Potable Reuse: The planned use of recycled water to replenish drinking water supplies with a
suitable environmental barrier. Suitable environmental barriers can include soil or a surface water
reservoir.
Million Gallons Per Day (MGD): A measurement of water flow frequently used in measurement of
wastewater flow. There are approximately three acre-feet in every million gallons.
Ocean Outfall: A pipeline extending into coastal and ocean waters that is used by a wastewater treatment
facility to discharge treated waste effluent or treatment byproducts such as brine.
Proposition 218: Commonly referred to as the “Right to Vote on Taxes Act”, the intent of Proposition 218
is to ensure that all taxes and most charges on property owners are subject to voter approval. In addition,
Proposition 218 seeks to curb some perceived abuses in the use of assessments and property-related fees,
specifically the use of these revenue-raising tools to pay for general governmental services rather than
property-related services.
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Recycled Water: Wastewater that is treated and reused for irrigation, groundwater recharge, surface
water augmentation, industrial water use, and environmental restoration.
Return Flow: Percolation of irrigation water into the groundwater basin that occurs when water is
supplied to irrigated crops or vegetation 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.
Reverse Osmosis: A water/wastewater treatment process that removes contaminants from water by
using pressure to force water molecules through a semipermeable membrane.
Safe Yield (Groundwater): The amount of groundwater that can be withdrawn from a groundwater basin
over a period of time without exceeding the long-term recharge of the basin or unreasonably affecting
the basin's physical and chemical integrity.
Surface Water Augmentation: The planned placement of recycled water into a surface water reservoir
used as a source of domestic drinking water supply.
Surface Water Groundwater Interconnection: When surface water seeps into the ground and recharges
the underlying groundwater aquifer, or when groundwater discharges to the surface and supplies the
stream with additional flow.
Tertiary Treated Recycled Water: Water treated to a point that meets or exceeds the standards
established by the California Department of Public Health according to Title 22 of the California Code of
Regulations for non-potable water intended for unrestricted use.
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I. Introduction
The Recycled Water Maximization Study compiles
information from previous reports such as the 2017
Recycled Water Master Plan (RWMP) and the Recycled
Water Facilities Planning Study (RWMP, Appendix A), as well
as recent work related to recycled water pricing strategies
and analysis of legal and regulatory constraints for recycled
water program expansion. This study serves as an overview
of key information that will guide the City through
maximizing the use of recycled water while protecting this
investment for the community. As stated in the adopted
2017 RWMP, the City plans to put recycled water to its
highest use as an additional potable water supply for the
community of San Luis Obispo.
While the overall goal for long-term use as a potable supply
remains, much has changed around recycled water in the
past five years. As part of the City’s 2021-23 Financial Plan, the City Council authorized funding for staff
to develop this study, which will be used to determine the feasibility of further expanding recycled water
resources for the benefit of the community, including what short-term options exist for utilization of
surplus recycled water until this resource can be utilized as a drinking water supply in the future.
This Recycled Water Maximization Study provides information and analysis of the following topics which
are critical in the City’s strategy to maximize its recycled water resources:
1. Background Information. Historical and background information on how recycled water is used
in the City and recent changes to State-approved uses.
2. Maximization Strategies. Short-term and long-term strategies to maximize the use of recycled
water supplies.
3. Issues if Delivered outside of City limits. Areas for discussion and consideration when examining
outside-City delivery of recycled water, including legal risks, supply availability, pricing strategies
for external delivery, and compliance with existing City policies.
II. Recycled Water Background Information
The Central Coast of California experienced a significant drought from 1987 to 1992 resulting in near
depletion of the City’s surface water supplies stored in Whale Rock and Salinas Reservoirs. This period of
drought preceded the City’s partnership in the Nacimiento Water Project (a current and third surface
water supply for the City), and also stressed the City’s groundwater supplies, which were at the time
heavily relied upon. During this period of drought, the City implemented stringent water conservation
measures that reduced the City’s overall water use by 40%. In addition to permanently changing the water
use characteristics of the community, this drought highlighted the need for greater water resiliency and
was the driving force behind significant investments in the Nacimiento Water Project and the City’s
recycled water program. These two projects were constructed to enable the community to meet its
current and projected water needs and to make the City’s water supplies more resilient during periods of
extended drought or other loss of supply. Today the City of San Luis Obispo receives water from three
Recycled water generally refers to
wastewater that is treated and reused
for irrigation, groundwater recharge,
surface water augmentation,
industrial water use, and
environmental restoration. In addition
to traditional utilization of recycled
water for irrigation use, cities are now
developing strategies to maximize
recycled water through advanced
treatment technologies, where
recycled water can ultimately be
utilized as a drinking water supply.
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surface water sources (Whale Rock, Salinas, and Nacimiento), limited groundwater for non-potable uses,
and recycled water.
Currently Approved Uses of the City’s Recycled Water
The City’s recycled water supplies are currently treated and
produced at the City’s Water Resource Recovery Facility (WRRF)
to tertiary standards, as defined by State regulations, which
allow recycled water to be used for urban landscape irrigation,
agricultural irrigation, and other de minis non-potable uses. As
of 2022, the City’s recycled water supply is used almost
exclusively for landscape irrigation, with small volumes being
utilized for dust control, grading, and soil compaction at large
construction sites. While permitted for irrigation use, tertiary
treated recycled water is not permitted for recharging
groundwater basins, for surface water augmentation, or for
human consumption.
When applications for private development are received by the
City, Utilities staff review the project to determine if the project
site is within the recycled water delivery area and identify what site improvements or infrastructure is
needed to connect the project site to the City’s recycled water system. Larger developments and
annexations are reviewed to determine if public improvements, consistent with the RWMP, should be
required as a component of the project approval process, based on the project’s demand and associated
impact on the recycled water system.
To ensure compliance with the State’s regulations prohibiting over-application of recycled water, which
could result in degradation to the groundwater basin, City staff conduct a thorough review of how recycled
water is planned to be utilized, along with the anticipated quantity that will be used at each site applying
for new service. This review is performed to ensure that the amount of recycled water used does not
exceed agronomic rates; recycled water is only permitted to be applied in the volume required by the
plants being irrigated and is not allowed to be over-applied to intentionally induce groundwater recharge.
Potential Future Uses of the City’s Recycled Water
The WRRF is currently undergoing a comprehensive upgrade (SLO Water Plus), which is projected to be
completed and operational in early 2024. The upgrade to the WRRF will result in increased treatment
capacity, increased production of recycled water, and updated treatment and operational processes,
which will result in significant long-term environmental, water quality, resiliency, and community benefit.1
In addition, the City Council approved upgrades to the WRRF that would position the City to utilize
recycled water for groundwater recharge or surface water augmentation in the future.
The use of recycled water for groundwater recharge has been permitted in California since 2014, and
surface water augmentation has been permitted in the state since 2018. Often referred to collectively as
1 For more information regarding the SLO Water Plus Project, please see City website:
https://www.slowrrfproject.org/
The State defines “disinfected
tertiary recycled water” as a filtered
and subsequently disinfected
wastewater. Disinfection methods
consist of either chlorine application
meeting specific parameters or
other process that inactivates or
removes specific disinfection-
resistant virus (such as polio). The
process must also result in coliform
bacteria concentrations below
specific levels. California Code of
Regulations Title 22, §60301.230
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Indirect Potable Reuse (IPR), these two uses of recycled water require additional treatment processes,
commonly referred to as Advanced Treatment. Advanced Treatment is often used to mean additional
engineered treatment after tertiary treatment of wastewater to remove contaminants of concern to meet
public health requirements. However, the exact makeup of advanced treatment required for an IPR
project can be specific to the site of the project and to the intended end use of recycled water
(groundwater recharge or surface water augmentation).
Advanced treatment of recycled water requires the use of reverse osmosis (RO) in California. Reverse
osmosis is a water purification technology that creates a byproduct known as brine, that is generally not
cost effective to dispose of unless a community has an ocean outfall for brine disposal. As the City of San
Luis Obispo is not proximate to the coast, and does not have an ocean outfall, the use of reverse osmosis
is not currently economically feasible for the City; however, regional partnerships are being explored that
may create opportunities for RO-based treatment. Since many of California’s water stressed communities
are not able to cost effectively remove brine, California’s potable reuse regulations have an “alternatives
clause” which provides an alternative permitting pathway for communities that cannot implement
reverse osmosis or have other regulatory hurdles that need to be overcome. The potable reuse
alternatives clause allows the City to replace the reverse osmosis process with treatment technologies
that prove to be equally effective. This alternatives track requires substantial permitting and a multi-year
“demonstration period” in which the advanced treatment facility must demonstrate that treated water
continually meets water quality parameters. For the City, alternatives clause technologies would likely
include a treatment series consisting of membrane bioreactors (MBR), ultraviolet light (UV), ozone,
biologically activated carbon (BAC), granular activated carbon (GAC), ultraviolet advanced oxidation
(UV/AOP), and chlorination. When planning the WRRF upgrade, the City opted to utilize MBR and UV in
the wastewater treatment processes, which will reduce the cost of advancing from tertiary treated
recycled water to advanced treated recycled water should the City opt to pursue permitting through the
alternatives clause.
III. How Much Recycled Water is Available for Use?
Changed Conditions Since 2006
The City’s recycled water program came online in 2006. Since that time many conditions and regulations
have changed, resulting in the need for reexamining the City’s strategy to optimize recycled water use. As
discussed in more detail below, wastewater influent has substantially decreased since 2006 due to
enhanced water conservation efforts, while the demand for recycled water has increased each year.
Without acknowledgement of these changed conditions, the City not only risks underutilizing its recycled
water supplies, but it also risks overallocation of this limited resource.
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Decrease in Recycled Water Supply
Since the inception of the City’s recycled water program, wastewater influent (which is utilized to produce
recycled water) has decreased from approximately 5,000 acre-feet per year in 2006 to approximately
3,200 acre-feet per year in 2022. During the same period that influent was rapidly decreasing, the
community expanded by approximately 1,500 residents, Cal Poly’s attendance increased by
approximately 3,000 students (the City currently treats all wastewater generated on the Cal Poly campus),
and business and tourism in the City increased substantially. Most of the decrease in available recycled
water can be attributed to decreases in indoor water use resulting from statewide water conservation
standards and the City’s aggressive water conservation programs. Table-1 below documents the
decreasing volume of wastewater treated at the WRRF at three-year intervals.
Table-1 - Wastewater Influent (Three-Year Intervals)
Calendar Year Millions of Gallons Per Day Acre-Feet Per Year
2007 4.36 4,887
2010 4.69 5,257
2013 3.15 3,530
2016 2.51 2,813
2019 3.63 4,0681
2022 2.88 3,2282
Notes:
1. Wastewater influent average for 2019 was abnormally high due to wet weather resulting in increased influent Jan-Apr.
2. Wastewater influent for 2022 is estimated for October, November, and December.
Increase in Recycled Water Use
Concurrent with the City’s wastewater influent decreasing and corresponding decreases in recycled water
production, the City’s recycled water user base was growing substantially, resulting in increased recycled
water demand. Table 2 below documents annual recycled water demand growth at three-year intervals.
This increased use is largely attributed to use of recycled water at large City parks such as Laguna Lake
Park, Islay Park, French Park, and Damon Garcia Park and landscape irrigation within expansion areas such
as Righetti Ranch, San Luis Ranch and Avila Ranch.
Table-2 - Recycled Water Demand (Three-Year Intervals)
Calendar Year Acre-Feet Per Year
2007 77
2010 153
2013 177
2016 193
2019 215
2022 3001
Notes:
1. 2022 Recycled Water Demand is estimated for October, November, and December.
Creek Discharge Requirement Modifications
Not all treated wastewater produced at the WRRF can be utilized for recycled water. When the City
initially received its State Water Board issued Master Reclamation Permit, which authorizes its use of
recycled water, the City was required to discharge 1.1 Million Gallons Per Day (MGD) of recycled water to
San Luis Obispo Creek. Two years later in 2005, prior to the recycled water program making its first
delivery, the City was required by the National Oceanic and Atmospheric Administration (NOAA) to
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increase creek discharge from 1.1 MGD to 1.6 MGD. This modification reallocated 500,000 gallons per day
of water from potential irrigation use to permanent delivery to San Luis Obispo Creek to support steelhead
habitat.
Anticipated Changes to Recycled Water Availability and Demand
Just as conditions have changed greatly since the launch of the City’s recycled water program, staff
anticipate that conditions will continue to change as California mitigates and adapts to climate change
impacts, develops water supply augmentation projects to return groundwater basins to sustainability, and
as technology and regulations advance, allowing for expanded uses of recycled water. Below are
anticipated changes that City staff, the City Council, and the community should consider when planning
for the future use of recycled water.
Increased Water Conservation Regulations
Water conservation regulations in California are expanding rapidly and reducing water demand across the
state. While the state is focused on reducing both indoor and outdoor water use, landscape irrigation
reductions do not impact wastewater influent volumes. This section speaks to decreased recycled water
production resulting from indoor water conservation regulations and water use efficiency standards in
California. Until Senate Bill X7-7 was passed in 2009, most water conservation programs in the state were
locally controlled and not stipulated by state law. Today, the state has taken an active role in setting
conservation standards for urban water purveyors and has also driven significant increases in water use
efficiency standards for indoor plumbing fixtures such as toilets, showerheads, and faucets. In September
2022, Governor Newsom signed Senate Bill 1157, which outlined that urban water purveyors must reduce
indoor water use for residential customers from a standard of 55 gallons per capita daily (gpcd) in 2020,
to 47 gpcd by 2025, and then to 42 gpcd by 2030. While initial analysis indicates that the City is already
compliant with the 2025 standards, statewide drought messaging and continued fixture efficiency
improvements are likely to drive the City’s indoor residential water consumption well below 42 gpcd by
2030. As the state continues to adopt more stringent water use efficiency and conservation measures,
the City’s recycled water supplies will be further reduced.
Expansion of Recycled Water Irrigation
The City continues to expand to meet the needs of the community, and several large developments are
either partially constructed or soon to be constructed within City limits. Most of these large developments
are located within the City’s recycled water service area and will be required to connect to recycled water
for irrigation of common areas and streetscapes. Additionally, as these developments are completed,
recycled water will also be extended to additional City facilities such as Sinsheimer Park and Johnson Park.
It is anticipated that the City’s recycled water demand will increase from 300 acre-feet per year to
approximately 600 acre-feet per year as development projects within the recycled water service area are
completed. This increase in recycled water demand will further intensify seasonal constraints on recycled
water availability. Further detail regarding recycled water availability for outside-City delivery will be
provided in the Outside-City Delivery Considerations section of this report.
Cal Poly Wastewater Reclamation Facility Construction / Master Plan Expansion
The City currently treats all of Cal Poly’s wastewater flow at the City’s WRRF. As Cal Poly developed a
strategy to outline the planned expansion of the campus, they determined that the university did not have
sufficient water supplies to meet the needs identified in their master plan. University staff determined
that future water needs could be accommodated by constructing a Wastewater Reclamation Facility
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(WRF) on Campus. This facility would treat all wastewater generated from Cal Poly’s new master plan-
associated construction to tertiary treated recycled water standards, where it could be used for
agricultural irrigation and landscape irrigation. Using this water for irrigation would then free up water
supply in Whale Rock Reservoir for Cal Poly’s domestic needs associated with its master plan expansion
area.
While Cal Poly’s long-term plan is to utilize their new WRF to treat all wastewater generated by their
campus expansion, and to continue to deliver wastewater from the existing campus to the City’s WRRF,
there is a period where this may not be feasible and could result in a reduction in wastewater flow to the
City. When Cal Poly constructs its WRF in 2025, expansion will likely be minimal and will not generate
enough new wastewater flow to operate the treatment facility. Until a substantial portion of Cal Poly’s
new development is completed, it is possible that Cal Poly will need to redirect part or all of the
wastewater flow from their existing campus to the new WRF. This temporary transfer of wastewater flow
from the City WRRF to the Cal Poly WRF is necessary to operate the Cal Poly facility, as the wastewater
treatment equipment and recycled water production equipment will have minimum flow requirements
to run effectively. The volume of redirected wastewater and timing of this temporary reduction in flow is
unknown at this time but is likely to start in 2025 and carry forward with varying impact through 2035. Cal
Poly has initiated preparation of an Environmental Impact Report (EIR) to evaluate the proposed WRF
project; this process will include further coordination with the City and is anticipated to provide additional
information regarding the project’s impact on the City’s WRRF and associated recycled water production.
Sustainable Groundwater Management Plan (SGMA) Impacts
In accordance with SGMA, the City began drafting the San Luis Obispo Valley Basin Groundwater
Sustainability Plan (GSP) alongside the County of San Luis Obispo (County) in 2019. This GSP documented
groundwater conditions in the San Luis Obispo Valley Groundwater Basin (SLO Valley Basin) and identified
that groundwater conditions varied significantly throughout the basin. In areas of the basin underlying
the City, often referred to as the San Luis Subarea, groundwater conditions remain stable, with a 700 acre-
foot per year surplus volume of groundwater. On the opposite side of the basin, in the agricultural areas
of the Edna Valley (Edna Valley Subarea), groundwater pumping is not sustainable and exceeds
sustainable yield by approximately 1,100 acre-feet per year.
The GSP had two major takeaways that are important to how recycled water supply and demand may
change in the future.
1. The GSP documented that the City’s portion of the groundwater basin is very small and can
meet less than 20% of the City’s water need each year. However, there are areas of the basin
within City limits where recycled water could be utilized to recharge the groundwater basin,
increasing the volume of groundwater available to the City annually. Recharging the
groundwater basin with recycled water requires that the City further treat its recycled water
to advanced treatment standards, which may require special permitting from the State, and
could take 6-8 years from permitting and construction through initial operation. Despite the
small groundwater basin size, it is estimated that the entire available volume of recycled
water could be utilized for groundwater recharge in the future.
2. The GSP discussed the potential for the sale of the City’s surplus recycled water supplies to
the Edna Valley Subarea to offset groundwater pumping. The GSP identified that
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approximately 500-800 acre-feet of recycled water could be delivered to the Edna Valley
Subarea for a five-to-ten-year period until the City pursues groundwater recharge or surface
water augmentation projects. Available recycled water volumes would not meet the entirety
of the estimated 1,100 acre-feet per year required to bring the Edna Valley Subarea into
sustainability and would not be available at all once the City moved toward potable reuse.
IV. Short Term vs. Long Term Maximization Strategy
Balancing recycled water availability and demand is a challenging topic that requires acknowledgement
that current conditions are likely to change substantially within the next five to ten years. While the City
has surplus supplies of recycled water available today, uncertainty exists around the impact that
conservation regulations may have on available supplies, how rapidly technology will expand the
approved uses of recycled water, and how Cal Poly’s new WRF may impact recycled water production for
the City. Acknowledging the uncertainty that exists around the future of recycled water, staff have
identified short-term and long-term strategies that maximize the use of recycled water. While long-term
strategies are focused on treating recycled water to make it a supplemental potable supply, short term
strategies focus on irrigation use but vary in complexity, as well as the nature and volume of benefit to
the community.
Long-Term Recycled Water Use
The City is in the final
stages of drafting a
Recycled Water Potable
Reuse Implementation
Plan. This plan outlines
the opportunities for
potable reuse in the future, a timeline for potable reuse project delivery, and treatment requirements
associated with different potable reuse alternatives. This study reinforces the City’s long-term strategy to
further treat recycled water to make it potable, providing added resiliency to the City’s water supply
portfolio. Below is a list of potential potable reuse pathways that the City could take in the coming years
to add a new potable water supply to the City’s water supply portfolio. Long-term projects have not
undergone a formal feasibility analysis and will be further studied in the coming years. All information
about these projects should be considered informational in nature and likely to change as more detail is
gathered
Groundwater Recharge Projects
As mentioned previously in this study, groundwater recharge requires advanced treatment of recycled
water, which can be achieved through the State’s approved advanced treatment process (including
Reverse Osmosis), or by pursuing equivalent treatment utilizing the alternatives clause2. For both
groundwater recharge projects listed below, staff are assuming that the City would be required to utilize
2 The alternatives clause is a regulatory option that allows water purveyors to utilize an alternative permitting
pathway to producing Advanced Treated recycled water in absence of the use of Reverse Osmosis. Advanced
treated recycled water can be utilized for groundwater recharge or surface water augmentation.
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the alternatives clause, due to the City not having access to an ocean outfall to dispose of reverse osmosis
brine.
Groundwater Recharge within the San Luis Subarea of the Groundwater Basin
Project Description: This project would consist of siting a recycled water percolation field or injection well
upstream of the City’s existing water supply wells which are located near Los Osos Valley Road. This
injection well or percolation field would be utilized to percolate or inject advanced treated recycled water
into the San Luis Subarea of the groundwater basin, at a location upstream of the City’s existing water
supply wells which are located along Los Osos Valley Road. After achieving appropriate treatment and
aquifer retention time3, the City could utilize existing groundwater wells to pump this water back out of
the basin for domestic use.
Benefits: Groundwater recharge within the San Luis Subarea of the SLO Basin provides unique benefits to
the City and is in alignment with climate action plan goals. If the City was to site a groundwater percolation
field or injection site within areas of San Luis Subarea underlying the City, recycled water could
supplement native groundwater in the basin and allow the City to increase groundwater pumping each
year. Additionally, the City could utilize existing groundwater wells for extraction and connection to the
City’s potable water system, reducing the need to construct new pumping and delivery infrastructure. As
the City continues to focus on reduction of greenhouse gas emissions, it is also important to recognize
that this option would reduce pumping costs for surface water supply delivery from the north county and
would not require energy intensive pumping to the Edna Valley for groundwater recharge in the Edna
Valley Subarea of the SLO Basin (alternative groundwater recharge option). In addition to environmental
benefit, the City would have rights to the entirety of the water injected into the basin and would not be
required to sell or exchange any of its available recycled water supplies in exchange for land, easements,
or other infrastructure.
Constraints: The City’s portion of the groundwater basin is small and has limited pumping capacity. The
City would need to increase groundwater pumping in the basin to free up capacity for this new water
supply to be percolated or injected into the groundwater basin. Unfortunately, due to the small size of
the basin, the City would not likely be able to bank and store large volumes of water for long-term use
and would be required to continually utilize the recycled water that was recharged into the basin.
Groundwater Recharge within the Edna Valley Subarea of the Groundwater Basin
Project Description: Staff have examined the potential to site a groundwater recharge project in the Edna
Valley Subarea of the SLO Valley Basin. This project would utilize the City’s surplus recycled water supplies
as a supply source. This project would exchange a portion of the City’s surplus recycled water supplies for
a site to inject or percolate the remaining supply into the groundwater basin in the Edna Valley.
Benefits: The benefit to utilizing the Edna Valley Subarea of the groundwater basin for recharge is that
this area of the basin has substantial available capacity, which could allow the City to bank water for
several years in the basin for storage. Banking water in the Edna Valley would also provide the City with
geographic diversity in its groundwater pumping program since the City’s groundwater wells are all
currently located on the southwestern side of town near Los Osos Valley Road. The City does not have
3 Groundwater recharge of advanced treated recycled water requires 2 -months of aquifer retention time before
being pumped for use as a potable supply.
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groundwater pumping capacity on the eastern of town and the San Luis Subarea cannot support the large-
scale groundwater banking that could be provided in the Edna Valley Subarea.
Constraints: While storage in the Edna Valley Subarea allows for long-term water banking, there are
several constraints to storage of advanced treated recycled water in this area. On the environmental front,
storage in Edna Valley would require energy intensive pumping of advanced treated water to this area
and additional pumping to return groundwater back into the City for use. Storage within this area would
also likely require that the City exchange some of its recycled water for rights to site a recharge project in
this location. Additionally, the City’s infrastructure to deliver recycled water to the Edna Valley Subarea is
undersized and not capable of delivery of all of the City’s surplus recycled water, which means the City
would not be able to fully utilize its recycled water supplies by delivering to the Edna Valley for
groundwater recharge. Later in this report, a detailed analysis of risks of delivery of recycled water outside
of City limits is presented. This section outlines considerations related to outside-City delivery of recycled
water which would be applicable to this project.
Surface Water Augmentation Projects
As discussed previously in this study, surface water augmentation projects in California require advanced
treatment of recycled water, which can be achieved through the State’s approved advanced treatment
process train (including Reverse Osmosis), or by pursuing equivalent treatment utilizing the alternatives
clause. For the surface water augmentation projects listed below that are conducted at the City’s Water
Treatment Plant (WTP) and the City’s WRRF, staff are assuming that the City would be required to utilize
the alternatives clause, given the absence of an ocean outfall to dispose of reverse osmosis brine. For the
regional project, it is assumed that the City would partner with a City that has an ocean outfall for brine
disposal. Staff have identified the City of Morro Bay, Avila Beach, and Cayucos Sanitary District as locations
with outfalls that could potentially be utilized for brine disposal. Formal discussions with these entities
related to potential partnerships have not yet been conducted.
Surface Water Augmentation (Whale Rock – Treatment at City WTP or City WRRF)
Project Description: City staff have identified that the City could potentially augment Whale Rock
Reservoir with advanced treated recycled water sited at the City’s WTP or WRRF. This project would
require the City to construct a new recycled water pipeline from the City’s WRRF to the WTP where
advanced treated water could be pumped to Whale Rock Reservoir for storage.
Benefits: This project provides unique benefit since the City already has water storage rights in Whale
Rock Reservoir. Due to the small watershed around the lake, and the large storage capacity of
approximately 40,000 acre-feet, it is uncommon for Whale Rock to be full, even during consecutive wet
years. It is likely that the City could store water in Whale Rock for several years, essentially allowing the
City to bank recycled water for future use as a potable water supply. Other benefits to surface water
storage in Whale Rock are that Whale Rock experiences very low levels of evaporation and that water
within Whale Rock is the highest quality of all of the City’s surface water reservoirs. Additionally, delivery
and treatment costs of Whale Rock supplies are substantially lower than those of Salinas and Nacimiento
Reservoir.
Constraints: Major constraints related to this project include high infrastructure costs for construction of
delivery infrastructure from the WRRF or WTP to Whale Rock. Electrical costs to pump advanced treated
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water to Whale Rock would also increase operating costs and greenhouse gas emissions when compared
to in-City groundwater recharge projects.
Surface Water Augmentation (Whale Rock - Regional)
Project Description: Surface water augmentation of advanced treated recycled water is more cost
effective if the City can enter into regional partnerships to cost share and increase the volume of water
that could be augmented in the reservoir. Additionally, taking advantage of existing infrastructure in other
communities, such as ocean outfalls could allow the City to utilize the standard advanced treatment
process, which requires reverse osmosis. A regional project for recharge of recycled water could include
partnerships with Cal Poly, Cayucos Sanitary District, Avila Beach, and the City of Morro Bay. Cal Poly and
the City both have storage in Whale Rock Reservoir, and both have expressed desire to increase potable
water supplies to increase long-term sustainability of their communities. Cayucos Sanitary District, Avila
Beach, and the City of Morro Bay are all constructing or considering construction of Wastewater
Treatment Facilities. These three communities also possess active ocean outfalls that could be utilized for
brine disposal. If the City could partner with any of these facilities, it could substantially reduce costs and
increase the sustainability of each community. It should be acknowledged that the City has not discussed
this partnership with potential partners at this time, nor has the Whale Rock Commission authorized the
use of Whale Rock by parties outside of the Whale Rock Commission.
Benefits: A regional partnership for surface water augmentation would benefit the City by allowing it to
leverage existing storage capacity within Whale Rock Reservoir to store advanced treated recycled water.
Other communities would also benefit as they may be able to negotiate for storage capacity within Whale
Rock Reservoir for advanced treated recycled water in exchange for utilization of existing ocean outfalls
or other infrastructure. As is with most water supply projects, the larger the group of participants, the
lower the cost burden on any individual party.
Constraints: Major constraints related to this project include high infrastructure costs for construction of
delivery infrastructure from the WRRF or WTP to Whale Rock. Electrical costs to pump advanced treated
water to Whale Rock would also drive costs up and increase greenhouse gas emissions. Other constraints
could include difficulty in negotiating an equitable deal with multiple partners, lack of confirmed support
from the Whale Rock Commission, or inability to secure the use of an ocean outfall.
Short-Term Recycled Water Use
With the City intending to utilize all surplus
recycled water supplies for potable reuse
in the future, it is important that the City
understand the timeframe for
implementation of a potable reuse project
and the opportunities for use of surplus
recycled water supplies prior to potable reuse implementation. In 2022, the City contracted with Carrollo
Engineering to conduct a study on the City’s strategy and timing for implementation of a groundwater
recharge or surface water augmentation project utilizing the City’s surplus recycled water supplies.
Through this study, Carrollo Engineering provided estimates that the City could have a fully operational
indirect potable reuse program within City limits in six to eight years if it committed to moving forward
with a project. Knowing this timeframe, the City has opportunities to expand recycled water use during
the interim timeframe to offset potable water demands, reduce pumping on the City’s side of the
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groundwater basin, or sell recycled water outside of the City to benefit the City’s water ratepayers. The
short-term delivery projects below could be pursued until the City moves forward with a potable reuse
project.
Expansion of In-City Recycled Water Irrigation
Project Description: This project would maintain the status quo, focusing expansion efforts on increasing
the use of recycled water for irrigation of local parks, business parks, and residential common areas. The
City is already permitted for this type of use of recycled water and has staff dedicated to fulfilling these
duties.
Benefits: There are several benefits to maintaining the status quo of expanding recycled water use inside
the City. Notably, the City is already permitted to use recycled water in this manner and has a strategy to
expand irrigation use in the 2017 Recycled Water Master Plan. Use of recycled water in the City also results
in an immediate offset to potable water demands, freeing up water within the City’s surface water
reservoirs for future use. This immediate offset to potable water use is important during periods of
drought, especially as the State generally exempts recycled water from conservation-related regulations.
City parks irrigated with recycled water provided great community benefit during the 2012-2015 drought
when the State required significant reductions in outdoor water use.
Constraints: With uncertainty around future recycled water availability, expansion of irrigation uses of
recycled water could result in over allocation of this supply during July, August, and September, when Cal
Poly is out of session and wastewater flow is reduced to the WRRF. However, minor over allocation during
the summer months would not offset the overall benefit to continued expansion for irrigation use.
Continued investment in irrigation system expansion must be monitored closely to minimize the over
allocation of recycled water during periods when Cal Poly is out of session or if Cal Poly is no longer able
to provide its wastewater effluent to the City’s WRRF.
Agricultural Offset within City’s Area of Groundwater Basin
Project Description: While the SLO Valley Basin GSP largely focused on overpumping of the Edna Valley
Subarea of the groundwater basin, significant agricultural groundwater pumping is also conducted in the
San Luis Subarea. From 2016-2019 agricultural pumping in the San Luis Subarea was approximately 1,370
acre-feet per year. Several agricultural operations in the subarea are adjacent to existing recycled water
pipelines and can utilize recycled water with minimal infrastructure investment. This project would
consider the delivery of recycled water to agricultural operations within the San Luis Subarea in exchange
for an equivalent reduction in groundwater pumping by these parties. This reduction in groundwater
pumping by agricultural operations could free up water within the groundwater basin for expanded
domestic use by the City.
Benefits: The benefits to this project include low financial costs, due to several agricultural operations
being proximate to existing recycled water lines. The City’s existing tertiary treated recycled water is
approved for use for agricultural irrigation and would not require further treatment. This project could
result in an immediate reduction in pumping by agricultural operations which could increase the volume
of groundwater that could be pumped by the City.
Constraints: While this project could be implemented quickly, water freed up in the groundwater basin
through this offset program could not be guaranteed to the City without programs and policies that
quantify and allocate groundwater pumping in the basin. In order be certain that this exchange resulted
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in increased pumping capacity, the City would need to work with a water rights attorney to better
understand the methods for appropriating this water to the City.
Contractual Sale Outside of City Limits
Project Description: This project considers the short-term sale of the City’s recycled water supplies
outside of the City limits. With current City policy restricting the outside-City delivery of recycled water to
use for agricultural irrigation, this project could include delivery to the Edna Valley, the Los Osos Valley,
Cal Poly, or to agricultural areas within the San Luis Subarea, but outside of City limits, such as areas along
Buckley Road, South Higuera, and Los Osos Valley Road.
Benefits: The benefit of delivering recycled water outside of City limits would be to assist in preservation
of the City’s green belt and to increase funding to the City’s Water fund for rate relief and expedited
project delivery.
Constraints: Delivery of recycled water outside of City limits is a new concept to the City and poses a series
of concerns related to protection of the City’s recycled water supplies. These concerns are outlined in
greater detail below in the Outside-City Delivery Considerations section of this report.
V. Outside-City Delivery Considerations
For any City water supply delivery project that expands beyond the City limits, it is important that the City
Council, City staff, and community members understand the risks associated with such delivery, the
impacts to the City’s water rate payers, and resources required for such delivery. This enhanced focus is
needed as the potential outside-City recipients of the City’s recycled water are not water rate payers and
have not made investments in the City’s existing water supply portfolio. Additionally, interested parties
outside of City limits are subject to policy requirements that limit the way recycled water can be used
outside of the City. The following sections will provide additional detail related to legal considerations for
outside-City delivery, supply and infrastructure limitations to outside-City delivery, pricing and cost
considerations to ensure protection of the City’s water rate payers, and an analysis of City policies related
to outside-City recycled water delivery.
Legal Considerations
Just as the City has rights to groundwater and surface water, the City has a right to the recycled water
that is produced at the WRRF, and it must ensure that this right is protected to retain the investment that
the community has made in its recycled water program. To protect the City’s investment in recycled water,
staff have coordinated with water rights attorneys to examine potential risks to water rights in relation to
the sale of recycled water outside of City limits. Additionally, the City must ensure that any action related
to its use of recycled water does not expose it to legal issues related to water rates, habitat creation, or
other potential legal risk. City staff have identified a number of specific concerns which are outlined below
with summarized analysis from legal counsel.
1. Obligation to Serve: Staff requested legal guidance regarding whether the State of California,
or a third party could compel the City to deliver its surplus recycled water supplies outside of
the City. Counsel advised that they do not believe that the City could be compelled to deliver
unallocated recycled water to a third party should the City Council opt not to pursue outside-
City deliveries at this time.
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2. Permitting: Staff requested legal analysis identifying the risk to the City in delivering recycled
water outside of the City limits under its existing permits. Legal Counsel advised the City that
it should require that any party receiving recycled water outside of City limits be required to
deliver this supply under its own permit with the State of California and that the City should
not allow a third party to conduct deliveries under the City’s delivery permit. This requirement
is especially important as the City does not have land use authority over areas outside of the
City limits which would complicate monitoring and enforcement of delivery provisions. It has
been acknowledged that the City would continue to be responsible for permitting associated
with treatment of recycled water, but it would not be advisable to hold permits related to
delivery. Despite not holding the permit related to the application of recycled water, the City
would likely need to amend its existing permits to include outside-City areas as approved
places of use for its recycled water supplies.
3. Sustainable Groundwater Management Act (SGMA): Staff requested legal analysis of the risk
and the impacts of SGMA-related legislation on the ability for the City cease delivery of
recycled water to a high priority groundwater basin that is in a state of overdraft. Legal
counsel has directed staff that it is unlikely that SGMA could compel the City to continue
delivery of recycled water to reduce basin overdraft and has advised that the City should make
any contract language clear as to its ability to cease delivery. An outside-City delivery contract
should also require that in the case of litigation between the City and the purchaser of
recycled water, recycled water deliveries would be ceased until litigation is resolved. It should
be acknowledged that SGMA is a new regulation that is un-litigated and therefore, delivery to
a basin subject to SGMA regulations has an increased risk to the City when compared to non-
SGMA basins.
4. Habitat Creation: Staff requested analysis of the risk of the delivery of recycled water creating
or reestablishing habitat within areas where recycled water may be delivered, and thus being
required to deliver recycled water indefinitely to support this habitat. Legal counsel has
advised that this is a potential risk that can be mitigated with appropriate studies and
monitoring infrastructure to ensure that the delivery of recycled water does not result in the
reestablishment of surface-water groundwater interconnectivity and/or creation of habitat.
In SGMA regulated basins, this may pose an issue, as one of the goals of augmented deliveries
or reduced groundwater pumping is to raise groundwater levels, which could result in
reestablishment of surface water groundwater interconnectivity, thus creating habitat. Staff
are cautious of this risk, as the City is currently required to discharge 1.6 million gallons per
day of water to San Luis Obispo Creek to ensure the protection of critical habitat that was
created by discharging treated wastewater to San Luis Obispo Creek. Prior to entering into
any agreement to sell recycled water to an overdrafted groundwater basin, appropriate
studies would need to be conducted and monitoring infrastructure would need to be installed
to ensure habitat is not created through outside-City delivery.
5. Cessation of Delivery: Staff have requested legal analysis of the potential risks associated with
a recipient of recycled water filing suit against the City if water deliveries are ceased in
alignment with the contract, the Water Shortage Contingency Plan, or due to infrastructure
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failure or emergency. Legal counsel has advised that appropriate contract language could
mitigate the risk of lawsuit in case of inability to deliver. Contract language for any delivery
agreement should not only be reviewed by an attorney specializing in contract law but also
by a water rights attorney familiar with California water rights law. While legal concerns are
important when discussing cessation of delivery, public perception should be considered in
addition to legal risk.
6. Groundwater Pumping Restrictions and Accounting: The City requested legal analysis as to
what accounting structure and pumping restrictions would need to be in place should the City
pursue a recycled water delivery project outside of City limits. Feedback from legal counsel
indicates that should the City intend to deliver recycled water outside of the City limits in an
effort to decrease groundwater pumping from a SGMA-regulated basin, a groundwater
banking program and policies that restrict expansion of groundwater pumping may be
necessary. The County of San Luis Obispo does not currently have any restrictions on
groundwater pumping in the SLO Valley Basin. The County also does not have measures in
place to prohibit expansion or intensification of agriculture in areas overlaying the SLO Valley
Basin, which could result in further issues related to groundwater level decline.
Outside-City Delivery Limitations
As discussed earlier in this report, the City has a variety of constraints related to the delivery of recycled
water outside of City limits. These constraints can broadly be categorized as availability limitations and
infrastructure limitations.
Availability Limitations
The City’s recycled water supplies have been decreasing since the recycled water program came online in
2006, with substantial decreases beginning in alignment with the 2012-2015 drought. Today, the City’s
total wastewater influent is approximately 2.88 MGD, or 3,200 acre-feet per year. Of this 3,200 acre-foot
total, 1,800 acre-feet of water is required to be discharged to San Luis Obispo Creek each year, leaving
approximately 1,400 acre-feet for use for recycled water delivery. The City’s recycled water program uses
approximately 300 acre-feet per year for landscape irrigation, with demand expected to grow to 600 acre-
feet by 2030 as the City continues to expand. When accounting for all of the City’s commitments to deliver
recycled water, approximately 1,100 acre-feet of surplus recycled water was produced in 2022, with
projected availability decreasing to 800 acre-feet by 2030. Recycled water availability for Calendar Year
2022 can be seen in Table 3 below.
Table-3 – Calendar Year 2022 Recycled Water Availability (in Acre-Feet Per Year)
Category Generation Demand Availability
Total Influent 3,200 - -
Creek Discharge (1,800) 1,400
Existing Customers (300) 1,100
Future Customers (entitled 2023-2030) (300) 800
Future Customers (not entitled 2030 - 2040) (400) 400
While 1,100 acre-feet of recycled water is available as surplus in 2022, it is important to understand that
that surplus volumes are predominantly available during winter months when irrigation demand is low.
During the summer months when Cal Poly is out of session the City does not have sufficient recycled water
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supplies available for outside-City delivery. However, from October through May each year the City should
have sufficient recycled water supplies to sell outside of City limits until it moves forward with an indirect
potable reuse project. It is also important to restate that this water cannot be stored in the groundwater
basin, or excessively applied to create additional water percolating into the basin without advanced
treatment.
Infrastructure Limitations
Should the City opt to enter into an agreement for outside-City recycled water sales, it may encounter
delivery constraints that are not related to volumes of available wastewater influent but instead are
related to infrastructure delivery limitations. Below are several infrastructure-related limitations that may
require restrictions to the volumes of recycled water delivered to outside-City customers or may require
financial investments to replace in order to maximize outside-City deliveries.
Piping Limitations
The City’s recycled water pipelines were not designed for delivery to outside-City customers and pipelines
decrease in size as they extend away from the WRRF and approach the edge of City limits. The City has
four potential alignments that could be utilized for delivery of recycled water outside of City limits for
agricultural irrigation. These alignments and maximum monthly delivery volumes can be seen in Table 4.
Maximum delivery volumes listed in Table 4 document the maximum volume of water that could be
delivered through these pipelines if none of the City’s existing irrigation customers were utilizing water.
Before entering into a contract to deliver recycled water outside of City limits, use patterns for existing
City irrigation customers would need to be factored into an availability analysis, which could further
reduce total monthly delivery volumes.
Table-4 – Outside-City Recycled Delivery Pipeline Capacity
Location Pipeline Size Maximum Flow
(GPM)
Maximum Monthly
Delivery (AF)
Los Osos Valley Road (North) 8” 800 106
Tank Farm Road 8” 800 106
Broad Street 6” 450 60
South Higuera 12” 1,800 238
Pumping Limitations/Automation Limitations
The City’s recycled water pump station was designed to serve recycled water to the City’s inside-City
customers for irrigation use. As the City considers delivery to outside-City customers, this pump station
may need to be upsized to efficiently meet demand requirements. The pump station will also require
reprogramming of computerized systems which automate delivery to maximize daily delivery. These
updates will be required to ensure that delivery to outside-City customers is not conducted during times
that would impact the City’s existing recycled water irrigation customers.
Pricing/Cost Considerations
Water rate setting is conducted differently from municipality to municipality across the nation. In
California, Proposition 218 establishes requirements for water rate setting, which at its most basic level
ensures that a customer’s water rates do not exceed their proportional share of the costs for delivery of
water services. In the context of delivery of recycled water outside of City limits, this means that outside-
City delivery could not negatively impact the City’s water rate payer. An example of a negative impact to
the City’s rate payer would be entering into any type of delivery agreement that did not recover all costs
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associated with this delivery or resulted in staffing resources associated with in-City delivery being utilized
to support contractual deliveries outside of the City without reimbursement.
To establish water rates, the City does not individually price water from each of its five water supplies
(Salinas, Whale Rock, Nacimiento, Groundwater, and Recycled Water). Rather, the City totals the costs of
all water-related operations and distributes this cost equitably amongst its customer base in
proportionality with their total use and the impact of their use on water infrastructure, staffing, etc.
Internal City rate payers currently pay approximately $5,100 per acre-foot for potable water and $4,600
per acre-foot for recycled water (90% of the potable water irrigation rate).
While outside-City recycled water sales contracts are not subject to Proposition 218, any sale of recycled
water at a rate of less than the cost to deliver such supply would result in inside-City rate payers
subsidizing these deliveries and would thus constitute a violation of Proposition 218. As the City has an
adopted methodology for pricing of its water supplies jointly, individualized costing of recycled water has
not historically been the basis for pricing recycled water but would be required in to provide
documentation that outside-City sales are not being subsidized by inside-City customers. In 2022 the City’s
water and wastewater rate consultant conducted a study of recycled water costs and revenues which was
the first step in understanding what types of costs are attributable to recycled water production and the
differentiation between recycled water costs, wastewater costs, and potable water costs. Further refining
of cost increases for outside-City delivery would need to be conducted on a case-by-case basis as outside-
City delivery scenarios can vary significantly in scope, duration, and benefit to the City’s water rate payers.
Since recycled water is produced at the City’s WRRF, which has a primary focus of treating wastewater,
any cost that is additional to that needed to meet wastewater treatment requirements is attributable to
recycled water and not to wastewater treatment. With the City’s upgraded WRRF this means that costs
related to additional ultraviolet treatment beyond permitted creek discharge requirements, chlorination,
storage, and pumping would be defined as recycled water costs, and not wastewater treatment costs.
Additionally, staffing resources associated with these processes at the WRRF are proportionately funded
through the water fund, not the sewer fund. In addition to equipment and staff at the City’s WRRF, the
City’s Water Distribution section is responsible for maintenance of the recycled water delivery pipelines,
meters, and other associated infrastructure. As was noted with the WRRF, time and resources spent by
the water distribution team on recycled water related work need to be considered for full cost recovery.
On the program management side of the equation, the recycled water delivery program is managed by
the water fund’s water resources section, where regulatory reporting, inspections, long-term planning,
and customer service is provided. Additional support for the recycled water program is provided by the
Utilities department’s administrative staff such as engineering, project management, and utility billing.
Outside of the Utilities Department, additional support provided by the Public Works department’s CIP
engineering team, the City Attorney’s Office, City Administration, and other support departments within
the City. Assistance provided from outside of the utilities department is funded through cost allocation
and would be subject to cost-recovery when negotiating an outside-City sales contract.
Although the City does not currently isolate direct costs for recycled water customers from those for
potable water customers as a basis for setting recycled water rates, staff conducted an analysis of
projected 2022-23 program costs and revenues and it is expected that revenue collected from recycled
water sales will exceed direct program costs this fiscal year. Given that the City’s recycled water rate is
adequate to offset direct program costs, the recycled water program can be considered independently
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sustainable. However, decreases to the rate for recycled water sales below the established rate of 90% of
the potable water rate could result in the program not covering its direct costs. If the recycled water
program does not cover direct costs, these costs must be offset by the City’s water rate payer.
To assist in understanding recycled-water related costs, Table 5 breaks recycled-water related costs into
three categories, as follows:
1. Fully Static Costs: Fully static costs are costs that are not variable in nature, and do not change
when recycled water production is increased or decreased. Examples include debt service,
permitting fees, and training costs for staff.
2. Fully Variable Costs: Fully variable costs are completely variable and linked directly to the
increased or decreased production of recycled water. Examples include electricity for pumping,
electricity for enhanced UV disinfection, and chemical costs.
3. Flat Rate Costs: Flat rate costs are costs that would not vary based on production volume but
would increase by virtue of adding a new type of delivery, with different permitting requirements,
delivery expectations, etc. Examples include staffing costs, automation system upgrades, and
pump station upgrades.
Table-5 – Recycled Water Cost Categories
Cost Category Static, Variable, Flat Additional Details Notes & Examples
Salaries and
Benefits
Flat Salary and benefit costs at
the for the City’s employees
to manage delivery to an
external City customer would
not increase proportionally
based on volume delivered
but would increase due the
outside-City customer not
receiving water in a manner
consistent with existing
deliveries.
WRRF and water
distribution staff
would need to
monitor recycled
water delivery to
ensure delivery to
external customer
could be maximized.
Admin staff would
need to monitor for
contract compliance
annually.
Program Costs Variable and Static Program costs are largely
static costs and not
dependent upon volume of
water treated. Minor
increases in program costs
are variable may occur as
recycled water production is
increased.
Variable Costs: meter
reading and pump
maintenance.
Static Costs:
Permitting, water
quality sampling,
employee
certification.
Debt Service
Repayment /
Impact Fees
Static Debt service payments are
static and do not increase
dependent on the volume of
water being delivered.
However, these costs could
be considered as an item for
potential repayment as
existing recycled water
Policy direction
required as to if
short-term outside-
City deliveries should
result in repayment
of sunk infrastructure
costs and debt
payments.
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Table-5 – Recycled Water Cost Categories
Cost Category Static, Variable, Flat Additional Details Notes & Examples
infrastructure was paid in full
by in-City water ratepayers.
Future RW CIP Static Outside-City contracts could
include only price increases
for CIP projects that provide
a recipient direct benefit.
These charges will vary year-
to-year but are not based on
contractual obligations to
outside-City customers.
May require policy
direction as to if
short-term outside-
City deliveries should
result in repayment
of future CIP such as
water tank
installation or pump
station replacement
Wear and Tear on
Equipment
Variable Wear and tear on equipment
and infrastructure increases
as equipment is used. This
cost should be shared with
outside-City customers in
proportion to total use.
Variable Costs:
Reduction in useful
life of pumps,
motors, pipeline, etc.
that serve in-City
customers.
Electrical Costs Variable Electrical costs increase as
the volume of pumping
increases. This cost should be
shared with outside-City
customers as a proportion of
total use, recognizing that
pumping to outside-City
customers will take place
during peak energy pricing
hours.
Variable Costs:
Consumption charges
and peak power
increases that would
not have otherwise
been triggered by in-
City customers.
Outside-City Pricing Options
The City does not have an established recycled water rate developed for outside-City delivery. Several
options for establishing rates for outside-City delivery of recycled water are as follows:
1. Status Quo / 90% of Potable Water Rate: One potential option for the delivery of recycled water
to customers outside of the City limits is to require that they pay the existing rate of 90% of the
potable water rate. This requirement would ensure that there is parity between inside-City
recycled water customers and outside-City customers but could discourage bulk purchases of
recycled water. This pricing strategy would result in outside-City customers paying approximately
$4,600 per acre-foot of recycled water purchased. By comparison, agricultural users are often
accustomed to only paying $50-$200 per acre-foot for direct pumping from a groundwater basin.
2. Variable Increases, Plus Flat Costs: This pricing option would directly bill the outside-City
customer for variable cost increases for electricity, chemicals, wear and tear on equipment, and
other variable costs. Additionally, this pricing structure would add flat rate costs to recover
expenses related to staff time, contract management expenses, regulatory reporting, etc. This
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rate structure would fully recover costs related to the delivery of recycled water outside of the
City limits but would not provide financial benefit to the City’s water rate payer. This rate structure
would also create a lack of parity between in-City customer rates and outside-City rates.
3. Proportional Share of all Recycled Water Costs: This pricing option would total all direct recycled
water program costs and would charge outside-City customers for their proportional (based on
per acre-foot demand) share of all of those costs. This rate structure would not create parity
between in-City customers and outside-City customers but would cover substantial program costs
if bulk quantities of recycled water were purchased, which would benefit the City’s water rate
payers. In alignment with this pricing strategy outside-City limits, the City could also elect to
modify its existing in-City recycled water rate to only recover direct costs. This methodology would
establish parity between inside-City customers and outside-City customers but would result in a
reduction in recycled water program revenue. This reduction in revenue would result in the need
to raise rates for the City’s water ratepayer and would require analysis as part of the City’s rate
setting process in Spring of 2023.
4. Options 1-3 Plus Profit: Any of the options above could be considered alongside a price increase
for profit for the City’s water ratepayer. The addition of profit would be most necessary with
option two, as this option would not otherwise provide benefit to the City’s water rate payers to
offset the risk of entering into an outside-City recycled water delivery agreement.
Policy Considerations
The City’s General Plan includes a variety of policies related to the delivery of potable, raw, and recycled
water outside-City limits. Most policies and restrictions on delivery of recycled water are outlined in
General Plan Land Use Element Policy 1.13.2 Recycled Water:
Provision of 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.
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 recycled water is being
provided.
While this Recycled Water Maximization Study is intended to identify how the City may maximize recycled
water use in the future, it intentionally does not examine delivery to one specific party. Therefore, this
study assumes that parties interested in purchasing recycled water from the City are located in areas
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proximate to City limits, where contractual delivery would be most economically feasible. These areas are
agricultural areas, with most located within the SLO Valley Groundwater Basin. Additional analysis may
be required if the City enters into formal negotiations for recycled water delivery to a specific customer,
especially if not located within the SLO Valley Groundwater Basin.
Preliminary Consistency with Policy Finding 1.13.2.A: Staff believes that the use of recycled water
within any of the agricultural areas surrounding the City would be in support of continued
agriculture and that delivery would be in alignment with Section A as the water would be used to
support crop production and agricultural operations.
Preliminary Consistency with Policy Finding 1.13.2.B: Staff examined the delivery of recycled
water to areas subject to the City’s GSP under two scenarios. The first scenario examines recycled
water delivery under existing County regulations, which do not limit or restrict existing
groundwater pumping, or expansion of pumping within the SLO Valley Groundwater Basin. The
second scenario examines policy compliance if parcel-by-parcel (or similar methodology) water
allotments were enacted, restricting increases in pumping within overdrafted areas of the basin.
Under Scenario 1, where groundwater pumping in the basin is unrestricted, staff do not believe
that the delivery of recycled water to overdrafted areas of the basin can be conducted in
compliance with Policy 1.13.2.B. The groundwater in the SLO Valley Basin is a joint resource that
is available for use by all parties with groundwater rights within the basin. Since groundwater is
interchangeable, importing recycled water to a single parcel (or area), frees up water in the basin
as a whole, thus allowing that freed up groundwater to be utilized to increase development
potential of neighboring properties. Without tracking, restrictions, and “capping” of basin
withdraws on a parcel-by-parcel basis (or using similar methodology), there is no way to ensure
that introduction of the City’s recycled water to a single parcel in the SLO Basin does not free up
groundwater at neighboring parcels, thus allowing increased development.
Under Scenario 2, where groundwater pumping within the SLO Basin is restricted and capped on
a parcel-by-parcel basis, staff believe that recycled water can be delivered to overdrafted areas
of the basin without increasing the development potential of the property being served. The
inclusion of regulations capping, or requiring a reduction in groundwater pumping, and requiring
that any imported water be utilized exclusively to decrease groundwater pumping, would ensure
that the City’s recycled water supplies were not being used to increase the development potential
of the properties outside of City limits.
Preliminary Consistency with Policy Finding 1.13.2.C: In accordance with Section C, recycled
water could not be sold outside of City limits and further treated to make it potable. While the
City has traditionally utilized a surface water treatment plant to treat its water, the state of
California recognizes that recycled water can be further treated through a series of advanced
treatment processes, and then utilizing the groundwater basin as an environmental buffer, the
water can be percolated through the soil and into the groundwater basin to make it safe to drink.
This process, generally referred to as indirect potable reuse (IPR), would further treat recycled
water to make it potable, and would not comply with Section C.
Should the City desire to sell recycled water outside of the City limits, it would need to be applied
at rates consistent with crop or vegetation water needs (agronomic rates), ensuring that
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unreasonable volumes of irrigation water would not percolate into the groundwater basin
without State-required advanced treatment. Return flow4 is allowable by the state in minimal
quantities as it is generally understood that irrigation is an imperfect process where water cannot
be applied to the plant in the exact quantity required, and sometimes results in irrigation water
percolating into the groundwater basin. Furthermore, at the time of negotiating a contract to sell
recycled water outside of City limits, the City would need to decide if it wanted to claim the return
flow as a developed water right. A developed water right could be claimed by the City as the
return flow water is not native to the groundwater basin and is therefore not the right of an
overlaying pumper or appropriator. Retaining rights to this developed water would ensure that
the use of the City’s recycled water for agricultural uses would not allow that water to later be
used as potable water or to encourage development.
Preliminary Consistency with Policy Finding 1.13.2.D: When examining the compliance of
recycled water delivery to agricultural areas adjacent to the City with Section D, staff have
identified that many of the potential recipients of recycled water have already entered into
Williamson Act agreements or other forms of conservation at this time. However, as mentioned
in the prior analysis of Section B, the use of recycled water to decrease groundwater pumping
means that shared groundwater resources are freed up and could be used for further
development. As with Section B, staff recommends that groundwater pumping be capped on a
parcel-by-parcel basis (or similar methodology) to ensure that the delivery of recycled water does
not encourage development within the City’s green belt.
In addition to the above-mentioned policies, General Plan Water and Wastewater Element Policy A 7.3.4
states that the City should “Consider the potential to deliver available 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 believe that these policies requirements have been
addressed in the previous sections of this report.
VI. Conclusion
The City has made ongoing investments in expanding its water supply portfolio over several generations.
These investments, paired with an aggressive water conservation program, have resulted in the City
being water secure, even during periods of extended drought. The City has multiple options that will
allow increased utilization of its recycled water resources in both the short and long-term. Short term
opportunities exist for the City to focus on further expansion of recycled water use to offset potable
water demands, as well as opportunities to sell or exchange this water to bolster groundwater supplies
and to increase the financial capacity of the City’s water fund. As new water supplies become more rare
and increasingly expensive, it is important that the City protects the investment it has made in its
4 Irrigation Return Flow: Percolation of irrigation water into the groundwater basin that occurs when water is
supplied to irrigated crops or vegetation 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.
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recycled water supply as it prepares for ultimate use of advanced treated recycled water as a potable
water supply.
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November 15, 2022
Recycled Water Program Timeline
•2006: Recycled water program launched.
•2017:City Council Adopted Recycled Water Plan, outlining strategy for future
use and authorizing outside-City sales (if in alignment with City policy).
•2017: WRRF selected equipment that would allow for future potable reuse of
recycled water.
•2019: City created recycled water model to understand future availability.
•2019-2022:City drafted Groundwater Sustainability Plan, which showed City’s
portion of groundwater basin was largely separated from the Edna Valley.
•2022:City drafted Recycled Water Maximization Study to outline use until
potable reuse is feasible.
2
Presentation Outline
Short-Term Strategy Irrigation Use Agricultural Offset Outside-City Sales Questions/Discussion
What is RW?Availability Future Uncertainty Long-Term Strategy Questions/Discussion
20 Minutes 10 Minutes
40 Minutes 20 Minutes
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 3
What is Recycled Water?
Tertiary Treated Recycled Water:
Water treated to a point that meets or exceeds the
standards established by the California Department of
Public Health according to Title 22 of the California
Code of Regulations for non-potable water intended
for unrestricted use.
Approved Uses
•Landscape Irrigation & Dust Control/Compaction
•Can not be utilized to recharge groundwater supplies
•Must be applied at agronomic rates
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 4
What is Recycled Water?
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
Indirect Potable Reuse
Direct Potable
Reuse
Advanced Treated Recycled Water:
Additional engineered treatment after tertiary treatment of wastewater to remove
contaminants of concern to meet public health requirements
5
How Much Recycled Water is Available?
Available ≠Usable
1.Delivery Location (pipeline capacity restrictions)
2.Time of year (seasonal constraints)
3.End Use (application can’t exceed agronomic rates)
4.When deliveries would begin (conservation and development will
impact future availability)
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 6
How Much Recycled Water is Available?
Table-3 –Calendar Year 2022 Recycled Water Availability (in Acre-Feet Per Year)
Category Generation Demand Availability
Total Influent 3,200 --
Creek Discharge -(1,800)1,400
Existing Customers -(300)1,100
Future Customers (entitled 2023-2030)-(300)800
Approximately 800 acre-feet per year
(City currently uses 5,000 acre-feet of potable water per year)
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 7
Uncertainty Regarding Future Availability
1.Decreased wastewater flow due to water conservation
•New conservation regulations require indoor water use to decrease from 55
gpcd to 42 gpcd by 2030.
•Indoor fixture efficiency improvements (toilets, sinks, showerheads, washing
machines, dishwashers, etc.)
•Conservation is certain to continue in the City.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 8
Uncertainty Regarding Future Availability
2.Cal Poly Expansion Impacting Wastewater Influent at WRRF
•Campus expansion through 2035.
•Plan to construct Water Reclamation Facility (WRF) on Campus.
•Cal Poly WRF will treat all new wastewater flow from campus expansion.
•Existing flow from current campus may need to be temporarily redirected to
Cal Poly WRF.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 9
Uncertainty Regarding Future Availability
3.Timelines for new development coming online
•Economic conditions impact timelines for construction.
•Increased wastewater generation will be offset by other community
conservation efforts.
•Most new development areas will utilize recycled water for irrigation.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 10
Long-Term Recycled Water Maximization Strategy
Indirect Potable Reuse
Direct Potable Reuse
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 11
Long-Term Recycled Water Maximization Strategy
State-Approved Advanced Treatment Train
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 12
•Requires use of Reverse Osmosis (RO) technology
•RO creates bring, which is not economical to dispose of without an ocean
outfall
•Use of RO would require partnership with a coastal community with an outfall
such as Avila, Morro Bay, or Cayucos.
Long-Term Recycled Water Maximization Strategy
“Alternatives Clause” Treatment Train
New Technology/Equipment
•WRRF was constructed with flexibility to add advanced treatment equipment.
•Could be constructed and operational in eight years.
•Requires “demonstration period” and special permitting.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 13
Long-Term Recycled Water Maximization Strategy
1.Indirect Potable Reuse: Groundwater Recharge
•Utilizes an “environmental buffer” (groundwater basin)
•Potential recharge location identified near Elks Lane
2.Indirect Potable Reuse: Surface Water Recharge
•Utilizes an “environmental buffer” (lake)
•Would require additional pipelines to Whale Rock Reservoir
3.Direct Potable Reuse
•Not yet approved in CA
•Does not have an environmental buffer
Why Groundwater Recharge?
•Utilizes an “environmental buffer” to ensure public health protection.
•Recharge location already identified near Elks Lane.
•In alignment with City’s climate action plan, as pumping long distances is
not required.
•Requires minimal additional piping infrastructure to transport for recharge.
•Would help with resiliency of groundwater supplies
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 14
City Council Discussion/Questions
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
Potential Discussion Topics
1.Is the City Council supportive of the plan to move toward groundwater
recharge as its long-term strategy for recycled water use?
2.If the City Council is not supportive of utilization of recycled water for
groundwater recharge, please provide direction on preferred use.
15
Short-Term Recycled Water Maximization Strategy
Three Goals for Short-Term Recycled Water Maximization
1.Protect City’s existing investment in recycled water.
2.Offset potable water use or supplement City’s water supply portfolio.
3.Generate revenue or cost-savings to benefit the City’s water rate payers.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 16
Short-Term Recycled Water Maximization Strategy
Optional Short-Term Strategies to Maximize Use
1.Continue to expand recycled water use for irrigation.
2.Exchange recycled water for a reduction in groundwater pumping within the
San Luis Subarea of the groundwater basin.
3.Sell recycled water outside of City limits.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 17
Short-Term Recycled Water Maximization Strategy
1. Expand In-City Irrigation Use of Recycled Water
Background Info:
•15 miles of recycled water delivery pipelines.
•Main pipelines exist (or will soon exist) on LOVR, Madonna, South Higuera,
Tank Farm, Orcutt, and Broad.
•Most infrastructure costs have been paid off (pipelines, tank, pump station).
•Expansion moving forward is cost-effective and will not require much new pipe
installation.
•Generates approximately $1.3M in revenue each year, which covers full
program cost, plus benefit to water rate payer.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 18
Short-Term Recycled Water Maximization Strategy
1. Expand In-City Irrigation Use of Recycled Water
Pros:
•Provides immediate offset to potable water use
•Can be accommodated with existing staffing and funding
•Provides revenue to the City’s water fund to offset rates
•Reduces pumping costs from distant surface water reservoirs
•Does not risk City’s future use of recycled water for groundwater
recharge
•No conservation regs from state (green parks during drought!)
Cons:
•Does not fully utilize available recycled water in winter months
•Requires capital funding for pipeline expansion
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 19
Short-Term Recycled Water Maximization Strategy
2. In-Basin Exchange for Reduction In Agricultural Pumping
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
Bedrock Divide
Edna Valley Subarea
(1,100 AF/Y Overdraft of
Groundwater)SLO Subarea
(700 AF/Y Surplus
Groundwater Supply)
20
Short-Term Recycled Water Maximization Strategy
2. In-Basin Exchange for Reduction In Agricultural Pumping
Background Info:
•1,370 acre-feet of agricultural pumping in SLO’s Subarea
•Some delivery areas would be inside-City, others outside-City
•Only feasible in areas of basin that are not overdrafted
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 21
Short-Term Recycled Water Maximization Strategy
2. In-Basin Exchange for Reduction In Agricultural Pumping
Pros:
•Reduces groundwater pumping, which could result in increased City
groundwater use.
•Increased groundwater pumping capacity would increase City’s water
supply resiliency.
•Increased groundwater pumping would reduce pumping from distant
reservoirs and GHG emissions.
•Could delay need to invest in groundwater recharge project, and
associated costs.
Cons:
•Would require additional funding to further develop.
•Could require that parcel-by-parcel groundwater allocations be
developed.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 22
Short-Term Recycled Water Maximization Strategy
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
3. Outside-City Sales of Recycled Water
LOVR
Cal Poly
South Higuera
Buckley
Edna Valley
23
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
Background Info:
•Could be delivered within the San Luis Subarea or Edna Valley Subarea.
•Would have different requirements if sold to an overdrafted area.
(will discuss later in presentation)
•Benefits to City and costs to receiving parties are different dependent on
customer.
•Pricing could vary based upon delivery location, volume, etc.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 24
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
Considerations for Outside-City Delivery
A.Legal Considerations
B.Availability/Infrastructure Limitations
C.Pricing/Cost Considerations
D.Policy Considerations
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 25
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
A.Legal Considerations (1 of 3)
•Permitting –Delivery outside of the City should be conducted only if
receiving party can procure a its own permit with State of CA to distribute
recycled water. City would hold treatment permit.
•Contract Requirements –Contract should be drafted to return water to
the City should a contract dispute or legal issue arise.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 26
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
A.Legal Considerations (2 of 3)
•Habitat Creation –Over-drafted
areas receiving City recycled water
must ensure through proper
studies and monitoring that
recycled water does not create
habitat through establishment of
groundwater/surface water
interconnectivity.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 27
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
A.Legal Considerations (3 of 3)
•Restriction of Increased Agriculture/Pumping –Policies restricting the
increase of groundwater pumping may be necessary in order to ensure
recycled water is utilized only to offset existing agricultural water use, and
not to expand groundwater pumping.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 28
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
B.Availability/Infrastructure Limitations
Table-3 –Calendar Year 2022 Recycled Water Availability (in Acre-Feet Per Year)
Category Generation Demand Availability
Total Influent 3,200 --
Creek Discharge -(1,800)1,400
Existing Customers -(300)1,100
Future Customers (entitled 2023-2030)-(300)800
Approximately 800 acre-feet available per year
(City currently uses 5,000 acre-feet of potable water per year)
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 29
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
B.Availability/Infrastructure Limitations
Table 4 –Outside City Recycled Delivery Pipeline Capacity
Location Pipeline Size Maximum Flow
(GPM)
Maximum Monthly
Delivery (AF)
Los Osos Valley Road (North)8”800 106
Tank Farm Road 8”800 106
Broad Street 6”450 60
South Higuera 12”1,800 238
Cal Poly1 NA NA NA
1. There is not currently a recycled water delivery pipeline to Cal Poly. If a pipeline was
installed, it could be sized to provide all surplus recycled water to the Campus.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 30
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
B.Availability/Infrastructure Limitations
•No recycled water available June-September.
•Impacts from conservation would need to be considered.
•Risk of changes at Cal Poly should be considered.
•Bulk delivery will require upgrade to City pump station.
•Programming to optimize delivery would need to be created
•Must ensure no impacts to existing customers
•Should ensure optimal delivery to reduce costs or maximize volumes
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 31
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations
•Must be compliant with Proposition 218 (cost recovery).
•Pricing could vary dependent on delivery costs and also depending on
benefit to City (inside City’s subarea vs outside).
•Benefit to the City would be dependent on pricing strategy selected by
City Council.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 32
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations
1.Should sunk costs be included in pricing?
•Original Project (storage tank, pump station, pipelines = $10M)
•Subsequent pipeline expansion projects (Tank Farm, Broad, etc.)
2.How much of existing costs should be borne by existing customers vs
contractual customers?
•Should outside customers pay for existing staff that treats RW?
•Should buildings, vehicles, & other operating costs be shared
with outside-City customer?
3.Should the water rate payers benefit (profit) from sale of surplus
recycled water?
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 33
Short-Term Recycled Water Maximization Strategy
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
Total Revenue Requirement ÷ Acre-Feet of Water Sold =
$5,100/Acre-Foot
Debt
Costs
Operating
Costs
Capital
Costs
How We Price Water
34
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations –Options for Pricing
•In-City Rate (90% of potable rate / $4,600 per acre-foot)
•Variable costs (electricity, chemicals, wear and tear) plus flat costs
(additional staffing, equipment upgrades, permit amendments, etc.)
•Proportional share of direct recycled water related costs
(total RW program costs ÷ acre-foot delivery)
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 35
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations –Options for Pricing
•In-City Rate (90% of potable rate / $4,600 per acre-foot)
Pros:
•Keeps pricing parity between in-City customers and outside-City
customers.
•Generates revenue for water fund.
Cons:
•Could exceed price agriculture is willing to pay.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 36
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations –Options for Pricing
•Variable Costs + Flat Costs
Pros:
•Covers expenses and is legally compliant.
Cons:
•Without separate profit structure, would not benefit the City’s
water fund / water rate payers.
•Does not maintain cost-parity between in-City customers and
outside-City customers.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 37
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
C.Pricing/Cost Considerations –Options for Pricing
•Proportional share of total RW program costs
Pros:
•Covers expenses and is legally compliant.
•Could provide financial benefit without separate profit structure if
in-City rates still set at 90% of potable rate.
Cons:
•Does not maintain cost-parity between in-City customers and
outside-City customers (if in-City rates still 90% of potable).
•If in-City rates are lowered, would place financial burden on
water rate payers after outside-City contract ends.
•Could exceed price ag operations are willing to pay for RW.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 38
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
D.Policy Considerations (1/2)
A.Non-potable/recycled water is necessary to support continued agricultural
operations.
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 recycled water is being provided.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 39
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
D.Policy Considerations (2/2)
B.Provision of non-potable/recycled water will not be used to increase
development potential of property being served.
•Recycled water used to offset groundwater pumping is “fungible”,meaning
recycled water would be utilized to “free up”groundwater in the basin.
•This groundwater is currently unregulated and can be pumped in any
volume,even overpumped.
•Staff interpret this policy to INTEND that the sale of City water not result in
growth due to the sale,not specifically at the “property being served”.
•Staff believe that groundwater extraction limitations must be in place for
the sale of recycled water to not allow for growth.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 40
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
Pros:
•Could reduce groundwater overdraft in agricultural areas outside of
the City / the City’s subarea.
•If structured correctly, could result in profit for the City, thus reducing
the burden on the City’s water rate payers.
Cons:
•Would require additional funding/staffing to further develop.
•Could require that parcel-by-parcel groundwater allocations be
developed.
•Could result in permanent habitat creation, if proper monitoring is not
in place.
•Depending on delivery location, may not provide water supply
benefit to the City.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 41
City Council Discussion/Questions
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
1.Does the City Council support the long-term strategy of utilizing recycled
water to supplement the City’s groundwater supplies, as identified in the City
Council adopted 2017 RWMP?
a)If the City Council is not supportive of utilization of recycled water for
groundwater recharge, please provide direction on preferred use.
2.If yes to continuation of existing long-term strategy (1a), please prioritize
options A, B, and C (below) for short-term recycled water maximization.
A. Inside-City recycled water expansion for irrigation use (current strategy).
B. Exchange recycled water for reduction in groundwater pumping in the
City’s subarea of the groundwater basin.
C. Sell recycled water outside of City limits.
D. A combination or all of the above.
42
City Council Discussion/Questions
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
3.Would the City Council like to continue to expand recycled water irrigation
within the City at historical funding levels? (approximately $400,000/year)
4.Would the City Council like staff to include funding for staffing resources,
consultant services, and other new costs for new short-term strategies (B, C) in
the 2023-25 Financial Plan?
43
City Council Discussion/Questions
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
5.If the City Council recommends requesting new budget in the 2023-25 Financial
Plan to pursue outside-City sales of recycled water, what pricing strategy would
the Council support for sale of surplus recycled supplies?
D. Sale at existing in-City Rates (90% of potable price).
E. Variable increases, plus flat costs (electricity, chemicals, wear and tear on
equipment, plus direct staffing and operating costs associated with outside -City
delivery).
F. Proportional share of all recycled water expenses based on per acre-foot use,
including sunk capital costs.
44
City Council Discussion
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion
6.Further Questions and Discussion?
45
SGMA: Groundwater Level Decline
46
SMGA: Edna Valley Agricultural Acreage
Acres of Agriculture within the Edna Valley
47
Edna Valley Subarea
Water Budget
SLO Valley Subarea
Water Budget
Return Flow
Edna Valley Agricultural Pumping: 3,440 AFY
Edna Valley Ag Return Flow: 570 AFY
Estimated RW Return Flow (800 AF of RW use):
133 AFY / enough water for 931 houses.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 50
Short-Term Recycled Water Maximization Strategy
3. Outside-City Sales of Recycled Water
D.Policy Considerations (3/3)
C.Non-potable/recycled water will not be further treated to make it potable.
•As recycled water is used for irrigation,a portion of this water percolates
naturally back into the basin as “return flow”.
•Return flow is not considered groundwater recharge and is permitted as
long as water is only applied at agronomic rates.
•Return flow water would be potable and could legally be pumped and used
for potable uses.
•This issue could be resolved by establishment of a groundwater banking
program,where the City received the right to all return flow water sold to a
third party.
What is RW?Availability Future
Uncertainty
Long-Term
Strategy
Short-Term
Strategy
Irrigation
Use
Agricultural
Offset
Outside-City
Sales
Council
Discussion 51