HomeMy WebLinkAboutItem 04 - 2020 Water Resources Status Report Department Name: Utilities
Cost Center: 6001
For Agenda of: January 19, 2021
Placement: Consent Item
Estimated Time: N/A
FROM: Aaron Floyd, Utilities Director
Prepared By: Mychal Boerman, Utilities Deputy Director - Water
Jennifer Metz, Utilities Projects Manager
SUBJECT: 2020 WATER RESOURCES STATUS REPORT
RECOMMENDATION
Receive and file the City’s 2020 Water Resources Status Report.
DISCUSSION
The 2020 Water Resources Status Report (2020 Report; Attachment A) provides an overview
and update on the City's water resources. This report covers Water Year 2020, which extends
from October 1, 2019 through September 30, 2020. Highlights for the Water Year include:
1. In July of 2020, the City received a nearly $2
million planning-phase grant, funded through
Proposition 1, to study Tetrachloroethylene (PCE)
contamination of the groundwater basin. A detailed
understanding of the extent of PCE contamination
and remediation options are necessary steps in
fully utilizing the City’s groundwater pumping
opportunities. The planning phase will continue
through 2021 with implementation planned for
2022.
2. Completion of two capital projects including
replacement of waterlines on Casa, Stenner, and
Murray Streets surrounding Sierra Vista Hospital
and the Disinfection Byproduct Reduction and
Water Treatment Plant Pipe Gallery Improvements
Project.
3. Approval and construction kickoff of the City’s
$14.3 million Water Energy Efficiency project at
the Water Treatment Plant. This project is a
collaboration with Pacific Gas and Electric through
their Sustainable Solutions Turnkey Program.
Water Energy Efficiency Project
Installation of new Ozone Generators.
Installation of new Dilution Air Dryers.
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4. Preparation of plans and specifications for a Spillway Underdrain Repair project and
the draft Emergency Action Plan update, at the Whale Rock dam.
5. Replacement of pressure relief valves for Whale Rock Pump Station B, 2,000 feet of fence-
line around Whale Rock Reservoir, and the Reservoir’s boathouse structure.
6. Work with the County of San Luis Obispo on the Groundwater Sustainability Plan under the
Sustainable Groundwater Management Act.
7. Review of the new Department of Water Resources guidelines for the 2020 Urban Water
Management Plan.
8. Total water demand in the City for the 2020 Water Year was 4,730 acre-feet, down from
4,762 acre-feet in the 2019 Water Year.
9. The average water use in the City, in terms of gallons per capita per day (gpcd), declined
slightly to 92 gpcd during the 2020 Water Year from 93 gpcd in the 2019 Water Year.
10. The City received above average rainfall at two of its reservoirs (Nacimiento and Salinas
reservoirs) and below average rainfall in the Whale Rock Reservoir watershed.
Table 1: Water Year 2020 Summary
Water Year 2020 Summary 4
(October 1, 2019 to September 30, 2020)
Total Water Use: 4,730 acre-feet
Potable Water Use 4,493 acre-feet
Recycled Water Use (includes landscape irrigation and
construction water) 237 acre-feet
2020 City Population 45,920
Per Capita Demand Per Day (Potable and Recycled
Water) 92 gallons
Water Projection Model (as of September 30, 2020) >5 years of supply
Annual Water Resource Availability:
Salinas and Whale Rock Reservoirs 4,910 acre-feet
Nacimiento Reservoir 5,482 acre-feet
Recycled Water (usage from 2019) 215 acre-feet
Siltation (from 2010 to 2060) (500 acre-feet)
Total: 10,107 acre-feet
Water Supply Accounting:
Primary Water Supply 1 7,496 acre-feet
Reliability Reserve 2 1,204 acre-feet
Secondary Water Supply 3 1,407 acre-feet
NOTES:
1. Per General Plan Policy A 5.2.2, primary water supply is the amount of water needed for General
Plan build-out using the water use rate established by policy A 5.2.1 (117 gpcd).
2. Per General Plan Policy A 5.2.3, reliability reserve that is 20-percent of the water use rate
established in Policy A 5.2.1 multiplied by the City’s current population (45,920 for 2020).
3. Per General Plan Policy A 5.2.4, secondary water supply is the remaining City water supply
available after accounting for primary water supply and a reliability reserve.
4. Values are rounded.
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Policy Content
The 2020 Report was prepared in accordance with the General Plan, Water and Wastewater
Management Element, Program A5.3.1.1
Public Engagement
Annual Water Resources Status Reports have been provided to the City Council and community
since 1985 and serve to both inform future policy decisions as well as provide historical
documentation of water conditions. The current year’s Water Resources Status Report is made
available on the City website.
ENVIRONMENTAL REVIEW
The 2020 Report is not a "project" under the California Environmental Quality Act (CEQA),
because the action does not involve any commitment to a specific project which may result in a
potentially significant physical impact on the environment, as contemplated by Title 14,
California Code of Regulations, Section 15378.
CONCURRENCES
Community Development concurs with these findings.
FISCAL IMPACT
There are no fiscal impacts associated with the recommended action.
ALTERNATIVE
The City Council could elect not to receive and file the 2020 Report and provide direction to
staff on desired modifications. Staff does not recommend this alternative, as the 2020 Report
was prepared in compliance with General Plan, Water and Wastewater Management Element,
Policy A5.3.1.
Attachments:
a - 2020 Water Resources Status Report
1 General Plan, Water and Wastewater Management Element, Program A 5.3.1, states “An update on water supply
accounting and demand projections will be presented to the City Council as part of the annual Water Resources
Status Report.”
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2020 Water Resources Status Report
For the Time Period October 1, 2019 through September 30, 2020
Stenner Canyon Water Treatment Plant.
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City of San Luis Obispo
2020 Water Resources Status Report
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The City’s 2020 Water Resources Status Report was prepared in accordance with the General Plan, Water
and Wastewater Management Element, Policy A5.3.1. The reporting period corresponds to the 2020
Water Year (October 1, 2019 through September 30, 2020), the twelve-month period for which
precipitation totals are measured designated by the calendar year in which it ends. This report provides a
summary of the following for the 2020 Water Year:
I. Regulatory and Water Capital Projects Update
II. Water Supply
III. Water Demand
IV. Water Resource Availability
V. Water Supply Accounting
I. CAPITAL PROJECTS AND REGULATORY UPDATE
The City completed two large water infrastructure projects during the 2020 Water Year and began the
implementation of a third project with capital improvements totaling over $18.7 million. These projects
are summarized below along with key regulatory updates related to the Sustainable Groundwater
Management Act and the upcoming update to the City’s Urban Water Management Plan.
Disinfection Byproduct Reduction & Water Treatment Plant Pipe Gallery Improvement Project
In August, the City completed the approximately $2.6 million Disinfection Byproduct Reduction and
Water Treatment Plant (WTP) Pipe Gallery Improvements Project. The Project included modifications at
two potable water storage tanks (Clearwell #2 at the WTP and Edna Saddle Tank) for the installation of
specialty equipment (mixers, aerators, and ventilators) to effectively reduce disinfection byproducts to
improve water quality and meet regulatory requirements. The Project also included replacement of
corroded pipe within the pipe gallery at the WTP, and the replacement of a sections of effluent line and
additional valving to provide a means for improved maintenance flexibility within the pipe gallery .
Water Energy Efficiency Project
In November 2019, the City Council approved the Water
Energy Efficiency project that includes $14.3 million of
improvements to the City’s Water Treatment Plant. The
benefits of the project include:
1. Contribute to the City’s sustainability goals and
advancement toward Zero Net Energy.
2. Reduce energy consumption and greenhouse gas
emissions.
3. Replace obsolete equipment and components.
4. Improve ability to perform maintenance.
5. Improve reliability of achieving permit compliance.
6. Increase operational reliability, flexibility, and
redundancy.
7. Reduced staff requirements for manual operation.
It is estimated that implementation of the Water Energy
Efficiency Project will result in a reduction of energy usage of
over 33 percent annually from 2019 WTP operations. The
project is approximately 50 percent complete, with Phase 1
Installation of new Ozone Generators.
Installation of new Dilution Air Dryers.
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Commissioning planned for early 2021. The Project is scheduled to be complete in mid-2021.
Waterline Replacement Projects
During the 2020 Water Year, the City completed replacement of over 3,000 lineal feet of waterline on
Casa, Stenner, and Murray Streets surrounding Sierra Vista Hospital at a cost of approximately $1.7
million. Replacement of water distribution pipes and related facilities is an ongoing program aimed to
address aging, substandard, and deteriorating infrastructure, with the added benefit of reducing
customer impacts associated with emergency repairs. Waterline breaks occur with more frequency with
aging waterlines, and the resulting repairs are disruptive to the public and expensive to repair. The main
objectives of this program are to ensure reliable water service, reduce the need for emergency repairs,
and to enhance available fire flows.
Capital Improvements at Whale Rock Reservoir
At the request of the California Department of Water Resources, Division of Safety of Dams, the City
began preparing plans and specifications for a Spillway Underdrain Repair project at the Whale Rock
dam, as well as the first draft of the Emergency Action Plan update, during the 2020 Water Year. The Plan
is under review internally by staff. The City performs this work with its Whale Rock Commission partners,
Cal Poly State University and the California Men’s Colony.
Ongoing capital improvements aimed at maintaining infrastructure safety and reliability include
replacement of pressure relief valves for Whale Rock Pump Station B, replacement of 2,000 feet of fence-
line around Whale Rock Reservoir, and replacement of the Reservoir’s boathouse structure.
Sustainable Groundwater Management Act
The use of groundwater will increase resiliency in the City’s water supply portfolio by offering a local
water source to complement the City’s three surface water supplies. The Sustainable Groundwater
Management Act (SGMA) is a statewide law that requires Groundwater Sustainability Agencies (GSA) to
adopt groundwater management plans that outline actions needed to return groundwater basins to
sustainable levels of pumping and recharge.
Sunset bike ride at Whale Rock Reservoir.
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City of San Luis Obispo
2020 Water Resources Status Report
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The City is working with the County of San Luis Obispo GSA to create a single Groundwater Sustainability
Plan (GSP) that provides full coverage of the San Luis Valley Groundwater Basin. To-date, the first seven
chapters of the GSP have been drafted and released to the public for review. To get additional
information, to sign up for the interested stakeholder email list, or to see materials for past or upcoming
meetings related to the GSP development, interested parties are encouraged to visit
www.slowaterbasin.com. The San Luis Valley GSP must be submitted to California Department of Water
Resources (DWR) by January 31, 2022.
2020 Urban Water Management Plan Guidelines
California’s Department of Water Resources issued its draft 2020 Urban Water Management Plan
Guidelines in August 2020. The State’s new requirements include:
1. Water loss audit results that characterize distribution system losses.
2. Procedures for conducting annual water supply and demand assessment.
3. Five-year drought risk asssessment.
4. Energy analysis.
5. A six-phase water shortage contingency plan.
Many of these new State requirements are already part of the City’s water planning , including the
preparation of this Water Resource Status Report annually. Staff will present more information to the
City Council on the new requirements at a March 2021 Study Session, with consideration of the City’s
2020 Urban Water Management Plan in June of 2021.
II. WATER SUPPLY
Per the General Plan Water and Wastewater Management Element, Policy A2.2.1, the City uses multiple
water sources to meet its water supply needs. The City has four primary water supply sources including
Whale Rock Reservoir, Salinas Reservoir, Nacimiento Reservoir, and recycled water. Groundwater serves
as the City’s fifth supplemental water source. Substantial work efforts are being made to better
understand the City’s groundwater supplies and how they may be fully utilized in the future. The quantity
of water supplied by each water source for Water Year 2020 (from October 1, 2019 to September 30,
2020) is summarized in Table 1.
Table 1: City Water Supply by Source during the 2020 Water Year
(in acre-feet)
Nacimiento
Reservoir
Whale Rock
Reservoir 2
Recycled
Water
Salinas
Reservoir Groundwater 3 Total City Water
Demand
1,562 777 237 2,154 0 4,730
33% 16% 5% 46% 0% 100%
Notes:
1. Values are rounded.
2. Water delivered to Cal Poly State University is excluded from the City’s water demand.
3. Groundwater was not used for potable purposes during Water Year 2020.
During Water Year 2020, 33 percent of the City’s total water demand was met by Nacimiento Reservoi r.
San Luis Obispo County operates and maintains the water delivery system from Nacimiento Reservoir to
participating agencies (currently the cities of Paso Robles and San Luis Obispo, Atascadero Mutual Water
Company, Templeton Community Services District, County Service Area 10A [Cayucos], Santa Margarita
Ranch, and Bella Vista Mobile Home Park). The Nacimiento Project Commission provides oversight to
project operations, maintenance, and the project budget. The Commission is made up of representatives
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from each of the four agencies’ governing boards and a County Representative who is a member of the
County Board of Supervisors who also sits on the Board of Directors for the Flood Control District.
During Water Year 2020, water demand totaled 4,730 acre-feet, below the ten-year average of 5,004
acre-feet (for 2011 to 2020), and the lowest total water demand since 2015. This is likely due to the
impacts of COVID-19. The City utilized a total of 2,931 acre-feet from Salinas and Whale Rock reservoirs,
meeting 62 percent of total City water demand. The City pays the County of San Luis Obispo Flood Control
and Water Conservation District (County) to provide oversight, operations, and maintenance of Salinas
Reservoir and related water delivery facilities. The City provides oversight, operations, and maintenance
of the Whale Rock Reservoir for the benefit of the Whale Rock Commission, a joint powers agency made
up of Cal Poly State University, California Men’s Colony, and the City.
For Water Year 2020, the City delivered 237acre-feet of recycled water for landscape irrigation and
construction water. This equates to five percent of total City water demand. New recycled water
customers during the 2020 Water Year include several properties in the Orcutt Specific Plan Area.
Although the City suspended using groundwater for potable purposes in April 2015, groundwater wells
remain in an operable, stand-by position should the use of groundwater be needed. In July of 2020,
the City received a nearly $2 million planning -phase grant, funded through Proposition 1, to study
Tetrachloroethylene (PCE) contamination of the groundwater basin. A detailed understanding of the
extent of PCE contamination and remediation options are necessary steps in fully utilizing the City’s
groundwater pumping opportunities. The planning phase will continue through 2021 with
implementation planned for 2022.
III. WATER DEMAND
During Water Year 2020, the breakdown of water use in the City by sector is as follows:
• 65.8 percent of water use supported single and multi-family residential uses, or
3,112 acre-feet,
• 20.8 percent of water use supported commercial and other non-residential uses,
or 984 acre-feet,
• 8.3 percent of water use supported separately metered landscape irrigation
(potable water), or 393 acre-feet,
• 4.4 percent of water use supported separately metered landscape irrigation
(recycled water), or 208 acre-feet, and
• 0.7 percent of water use supported construction (recycled water), or 33 acre-feet.
Compared to the prior water year, total City water demand for single and multi-family residential uses
increased from 60.5 percent in Water Year 2019 to 65.8 percent in Water Year 2020, likely due to both
remote work and remote learning during COVID-19. During the same timeframe, water demand for
commercial uses decreased from 28.4 percent in Water Year 2019 to 20.8 percent in Water Year 2020.
Historical water use is summarized in Table 2, as well as corresponding population, per capita use rate,
and rainfall. The 2020 per capita water use was 92 gallons per capita per day (gpcd). Per capita water use
is calculated by dividing total water use (including recycled water) in the City by the City’s population.
Total water use includes residential and daytime population needs for all uses such as restaurants, hotels,
industrial/manufacturing, government/schools, and irrigation. Based on the City’s General Plan Water
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and Wastewater Management Element policies, the City uses a factor of 117 gpcd to project water
required to serve the General Plan’s estimated population in 2035.
The City’s water supply reservoirs are in different watersheds, therefore rainfall at various locations
within San Luis Obispo County benefits the City. As shown in Table 3, during Water Year 2020, two
reservoir locations (Rocky Butte and Salinas Dam) received more than the annual average. The remaining
location, Hwy 46 and W 7 Mile Road, Cambria, CA, received less than average rainfall.
Table 2: Population, Water Use, and Rainfall, 2011-2020
Year Population3 Total Water Use
(acre-feet)
Per Capita Water Use
(gpcd) Rainfall1,2 (inches)
2011 45,418 5,285 104 18.9
2012 45,308 5,541 109 21.5
2013 45,541 5,892 116 3.8
2014 45,473 5,524 109 14.2
2015 45,802 4,990 97 11.8
2016 46,117 4,731 92 17.8
2017 46,424 4,975 95 35.1
2018 46,548 5,225 100 12.9
2019 45,9374 4,762 93 27.1
2020 45,920 4,730 92 21.59
NOTES:
1. Rai nf all for 2011 through 2012 calendar year source was from the Cal Poly CIMIS Weather Station. Rainfall for calendar
year 2013 through 2020 was from data for SLO Reser voir available from SLO County at:
https://wr.slocountywater.org/list/?sensor_class=11&mode=sensor&cache=1&refresh=off
2. Rainfall data for 20011-2014 is for the calendar year; 2015-2020 data covers the Water Year (October 1 to September 30).
3. City population data is available at the CA Department of Finance website at:
http://www.dof.ca.gov/Forecasting/Demographics/Estimates/e-1/
4. The City’s 2019 population figure reflects the revised estimate available from the CA Department of Finance in 2020 since
the 2019 Water Resource Status Report.
Table 3: Water Year 2020 Rainfall Totals
Rainfall Measurement
Location Watershed
Annual
Average
Rainfall
(in inches)
Water Year
2020
Total Rainfall
(in inches)
Water
Year 2020
Percent of
Average
Rocky Butte Nacimiento Reservoir 40 43.38 108%
Hwy 46 and W 7 Mile
Road, Cambria, CA Whale Rock Reservoir 30 17.49 58%
SLO Reservoir San Luis Obispo Creek 24 21.59 90%
Salinas Dam Salinas Reservoir 22 23.71 107%
Source: https://wr.slocountywater.org/list/?sensor_class=11&mode=sensor&cache=1&refresh=off
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NOTE: In 2016, the City recognized the full allocation of Nacimiento Reservoir increasing the City’s
contractual water supply from 3,380 acre-feet to 5,482 acre-feet annually (+2,102 acre-feet). Following the
end of the drought in 2016, the City updated the Safe Annual Yield model for Whale Rock and Salinas
Reservoirs incorporating rainfall data and three climate change scenarios. In 2018, the City recognized the
reduction from 6,940 acre-feet to 4,910 acre-feet in Safe Annual Yield (-2,030 acre-feet).
IV. WATER RESOURCE AVAILABILITY
The following table summarizes the Water Resource Availability based on Water and Wastewater
Management Element, Section 3. Water availability for Water Year 2020 is 10,107 acre-feet.
Table 4: Water Year 2020 Water Resource Availability
Water Resource Acre-Feet Description
Salinas & Whale Rock Reservoirs 4,910 Safe Annual Yield 1
Nacimiento Reservoir 5,482 Dependable Yield 2
Recycled Water 215 2019 Annual Usage 3
Siltation from 2010 to 2060 (500) WWME Policy A 4.2.2 4
10,107 2020 Availability
NOTES:
1. The City’s Safe Annual Yield model was updated in 2018.
2. Dependable Yield is the contractual amount of water the City has rights to from
Nacimiento Reservoir.
3. The quantity of recycled water included (215 acre-feet) is the actual prior year’s usage
(calendar year 2019) per General Plan Water and Wastewater Management Element
Policy A 7.2.2.
4. Reservoir siltation is a natural occurrence that reduces storage capacity over long
periods, resulting in the reduction of safe annual yield.
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V. WATER SUPPLY ACCOUNTING
Per General Plan Water and Wastewater Management Element (WWME), Section 5, the City accounts
for water supplies necessary to meet three specific community needs:
• Primary water supply
• Reliability reserve
• Secondary water supply
Primary water supply is defined as the amount of water needed to serve the City’s future residential and
non-residential water demand, based on the population identified in the General Plan, Land Use Element
(2014). Table 3 in the Land Use Element identifies an urban reserve capacity of 57,200 people1. The
quantity of water needed for the primary water supply is calculated per WWME Policy A 5.2.2, using 117
gallons per capita per day (gpcd).
The City’s reliability reserve is defined as the buffer for future unforeseen or unpredictable long-term
water supply impacts. The quantity of water for the reliability reserve is defined in WWME Policy A 5.2.3,
using 20 percent of the existing City population (45,920, 2020 population) at 117 gpcd. Based on this
policy, the reliability reserve will change over time as the City’s actual population changes. The reliability
reserve concept is included in the City’s Charter (Section 909) which identifies that the water may not be
used to serve future development.
The City’s secondary water supply is defined as the amount of water remaining from available water
resources above those needed to meet the primary water supply and reliability reserve. The secondary
supply is identified to meet peak water demand periods or short-term loss of City water supply sources,
per WWME Policy A 5.2.4.
Water suppl y accounting for the 2020 Water Year is summarized in the table below and shown in
Appendix A .
1 The City’s population projection of 57,200 persons, from the General Plan Land Use Element, is based one percent
growth annually between 2014 and 2035. By policy, certain housing types and areas are excluded from this growth
rate and projection (affordable housing, etc.). The City’s estimated Primary Water Supply need is based on
projected population but encompasses all water demand in the City (residential, non-residential, and irrigation). In
WY 2020, single-family and multi-family residential water demand was 65.8 percent of total City water demand.
2020 Water Supply Accounting
Primary Water Supply = 117 gpcd x City Build-out Population, in acre-feet per year
117 gpcd x 57,200 x 365 day/year x acre-ft/325,851 gallons = 7,496 acre-ft per year
Reliability Reserve = 117 gpcd x 2020 City Population x 20 percent, in acre-feet per year
117 gpcd x 45,920 x 365 day/year x acre-ft/325,851 gallons x 20 percent = 1,204 acre-ft per year
Secondary Water Supply = Current Annual Availability – Primary Water Supply – Reliability Reserve
10,107 acre-ft/year A – 7,496 acre-ft/year – 1,204 Acre-Ft/year = 1,407 acre-ft per year
A 2020 Annual Water Resource Availability from table above.
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Table 5: 2020 Water Supply Accounting (in acre-feet)
Primary Water Supply Reliability Reserve Secondary Water
Supply Total
7,496 1,204 1,407 10,107
SOURCE: Policies related to Water Supply Accounting are found in the City’s General Plan Water and Wastewater Management
Element (Policies A 5.2.2 through A 5.2.4).
In summary, the City maintains a robust water supply portfolio with greater than five years of wa ter
available. Per capita water use (obtained from adding up all water used by visitors, residents, commercial
uses, etc.) decreased during the 2020 Water Year to 92 gallons per capita per day (gpcd) from 93 gpcd
during the 2019 Water Year. City population figures, and associated gallons per capita per day, reported
in the 2019 Water Resource Status Report were updated from Department of Finance data.
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Appendix A.
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