HomeMy WebLinkAboutItem 05 - 2019 Water Resources Status Report
Department Name: Utilities
Cost Center: 6001
For Agenda of: January 14, 2020
Placement: Consent
Estimated Time: N/A
FROM: Aaron Floyd, Utilities Director
Prepared By: Mychal Boerman, Deputy Director – Water
Jennifer Metz, Utilities Projects Manager
SUBJECT: 2019 WATER RESOURCES STATUS REPORT
RECOMMENDATION
Receive and file the City’s 2019 Water Resources Status Report.
DISCUSSION
The 2019 Water Resources Status Report (Attachment
A) provides an overview and update on the City's
water resources in accordance with the General Plan,
Water and Wastewater Management Element, Program
A5.3.1. This report covers Water Year 2019 which
extends from October 1, 2018 through September 30,
2019.
The main takeaways from the annual report are as
follows:
1. The City has ample water supplies to serve existing
and planned development.
2. Water supplies remain healthy and the City has a
diverse water portfolio.
3. 2019 Water Year consumption was well below
established water supplies and was 22 percent less
than projected water demand for the City’s current population. Population growth was a total
of four percent over the last ten years increasing from 44,948 persons in 2010 to 46,802
persons in 2019.
4. Prudent planning, management, monitoring, and investment in infrastructu re and professional
staff will be key to the City’s continue ability to have resilient water sources.
Highlights include:
1. Risk and Resiliency Assessment. On October 23, 2018, America’s Water Infrastructure Act
of 2018 was signed. To comply, the City must conduct a Risk and Resilience Assessment and
revise its Emergency Response Plan by June 30, 2021 and December 30, 2021 to assess
infrastructure risks from natural and man-made hazards and plan for improved resilience and
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emergency response against those risks. The work is planned to be performed in-house by
Utilities Department staff.
2. Transmission Line Review and Maintenance Need Identification. During October and
November 2018, condition assessments were performed on over 16 miles of 30-inch
transmission pipeline from Whale Rock Reservoir and 1.25 miles of the transmission
pipeline that delivers water from Salinas Reservoir to the City’s Water Treatment Plant. The
condition assessments used free-swimming electromagnetic inspection technology to locate
and identify segments of the pipeline in need of repair. Needed repairs will be completed
during the 2020-21 fiscal year.
3. Above Average Rainfall. On February 3, 2019, Salinas Reservoir was full and spilling.
During Water Year 2019, three rainfall recording stations (Rocky Butte, SLO Reservoir, and
Salinas Dam) received more than the annual rainfall average. Whale Rock Reservoir reached
92 percent of capacity in May 2019.
4. Groundwater Sustainability Plan. On February 5, 2019, the City Council approved a
Notification of Intent to initiate development of a Groundwater Sustainability Plan. The City
is working in collaboration with the County of San Luis Obispo to create a single
Groundwater Sustainability Plan (GSP) that provides full coverage of the SLO Basin. To
comply with the Sustainable Groundwater Management Act, the GSP must be submitted to
California Department of Water Resources by January 31, 2022.
5. Short-Term Agreements. At a March 5, 2019 Study Session, Council supported the concept
of short-term water supply agreements for outside City deliveries for both non-potable and
recycled water supplies.
6. Whale Rock Spillway Assessment. Also, in March 2019, the Whale Rock Spillway
Assessment Report was completed with recommendations including maintenance and repair
activities for the drainage system and further engineering investigations.
7. Preparing for Power Shutoff Events. On August 20, 2019, in response to notification by
PG&E of the potential for Public Safety Power Shutoff events, the City Council approved
funding for emergency power needs for the Water Treatment Plant and other water facilities.
The City procured rental equipment to sustain its facilities through the short-term as well as
permanent portable equipment. The design of a permanent generator for the Water Treatment
Plant is underway and planned to be in place during the 2020 Water Year.
8. Per Capita Water Usage Decreased. Although the City’s population increased by over
250 persons in the last year, per capita water use decreased from 100 gallons per ca pita per
day in Water Year 2018 to 91 gallons per capita per day in Water Year 2019. The City’s
Annual Water Resource Availability increased slightly during the Water Year from 10,130 -
acre feet to 10,136-acre feet.
Policy Context
The 2019 Report was prepared in accordance with the General Plan, Water and Wastewater
Management Element, Program A5.3.1.
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 annually.
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Table 1: Water Year 2019 Summary
Water Year 2019 Summary
(October 1, 2018 to September 30, 2019)
Total Water Use: 4,762 acre feet
Potable Water Use 4,561 acre feet
Recycled Water Use 201 acre feet
2019 Population 46,802
Per Capita Demand Per Day (Potable Demand Only) 91 gallons
Water Projection Model (as of September 30, 2019) >5 years of supply
Annual Water Resource Availability:
Salinas & Whale Rock Reservoirs 4,910 acre feet
Nacimiento Reservoir 5,482 acre feet
Recycled Water (from 2018) 244 acre feet
Siltation (from 2010 to 2060) (500 acre feet)
Total: 10,136 acre feet
Water Supply Accounting:
Primary Water Supply 1 7,496 acre feet
Reliability Reserve 2 1,227 acre feet
Secondary Water Supply 3 1,413 acre feet
Total: 10,136 acre feet
NOTES:
1. Per General Plan Policy A 5.2.2, primary water supply is t he 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 (46,548 in 2018).
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.
CONCURRENCE
Community Development concurs with the environmental review findings.
ENVIRONMENTAL REVIEW
The 2019 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.
FISCAL IMPACT
Budgeted: N/A Budget Year: N/A
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Funding Identified: N/A
Fiscal Analysis:
Funding Sources Current FY Cost
Annualized
On-going Cost
Total Project
Cost
General Fund
State
Federal
Fees
Other: Water Fund N/A N/A N/A
Total N/A N/A N/A
There are no fiscal impacts associated with the recommended action.
ALTERNATIVES
The City Council could elect not to receive and file the 2019 Report and provide direction to
staff on desired modifications. Staff does not recommend this alternative, as the Report was
prepared in compliance with General Plan, Water and Wastewater Management Element, Policy
A5.3.1.
Attachments:
a - 2019 Water Resources Status Report
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2019 Water Resources Status Report
For the Time Period October 1, 2018 through September 30, 2019
Whale Rock Reservoir, August 2019.
Prepared by the Water Division of the City of San Luis Obispo, Utilities Department
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City of San Luis Obispo
2019 Water Resources Status Report
Page 2
The City’s 2019 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 Water
Year (October 1, 2018 through September 30, 2019), the twelve-month period for which precipitation
totals are measured designated by the calendar year in which it ends. This report for Water Year 2019 is
organized as follows:
I. Regulatory and Water Projects Update
II. Water Supply
III. Water Demand
IV. Water Resource Availability
V. Water Supply Accounting
I. REGULATORY AND WATER PROJECTS UPDATE
America’s Water Infrastructure Act
America’s Water Infrastructure Act of 2018 (AWIA) was signed
on October 23, 2018. AWIA is an update to the Bioterrorism Act
of 2002 of the Safe Drinking Water Act. AWIA outlines that
community water systems serving 3,300 persons must:
• Conduct a Risk and Resilience Assessment (RRA),
• Revise Emergency Response Plans (ERP),
• Submit a certification letter to EPA,
• Review and update at least every five years.
The Act requires the City to certify the RRA by June 30, 2021 and the ERP December 30, 2021.
Preparation for PSPS Events
To protect communities from wildfire, Pacific Gas & Electric (PG&E)
notified its customers of its plans to implement precautionary
measures during fire season. If extreme fire danger conditions
threaten a portion of the PG&E electrical system, high-risk
transmission lines may be turned off, resulting in potentially
widespread power outages to San Luis Obispo County. PG&E refers
to this as a Public Safety Power Shutoff, or PSPS event. According to
PG&E, a PSPS event may be necessitated by strong winds, low
humidity levels, and critically dry vegetation. PG&E advises these
outages will not be localized; regional solutions will be limited
because resources are likely going to be scarce on a local, regional and possibly a statewide scale. Nearby
communities have already experienced similar PSPS events from their power supplier.
Since being informed by PG&E of the potential for PSPS events, the City has worked to prepare for power
outages lasting up to seven days or more. In the past, the City has been able to continue to provide
uninterrupted water and wastewater service during short-duration power outages and when limited areas
were affected by utilizing existing water storage tanks with limited emergency power generation - some
of the City’s water and wastewater facilities have permanent emergency generators in place, while others
utilized a limited number of mobile generators. With the PSPS notification from PG&E and the changing
climate, staff identified additional emergency power resources for the City’s water and wastewater
systems to meet this increased duration.
Electrical power is the
greatest dependency of
water systems, with heavy
reliance on electricity to run
pumps and other system
components.
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With the support of the City Council in August, the
Utilities Department worked to quickly acquire
additional temporary emergency generators and
make necessary electrical improvements for the
Water Treatment Plant, Whale Rock Reservoir, and
other water pump stations and sewer lift stations.
The City has also been working closely with the
County of San Luis Obispo to acquire a generator for
the Salinas Booster station that provides water from
Salinas reservoir to the City. Installation of
permanent generators are planned for 2020. These
efforts will bolster the resiliency of the City’s water
and wastewater services from any event that could
result in loss of electricity.
Whale Rock Dam Spillway Assessment
The Whale Rock Reservoir and dam are located in San Luis Obispo County at the east boundary of the
town of Cayucos. The dam is 266 feet tall with a crest length of 850 feet and crest width of 30 feet
impounding Whale Rock Reservoir. The top of dam elevation is 232.2 feet. The Reservoir covers an area
of 600 acres and has a maximum storage capacity of 38,967 acre-feet. Dam construction was completed
in 1961. Whale Rock was constructed to provide municipal and agricultural water supplies, and fish and
wildlife preservation. Over the 58-year life of the Whale Rock Reservoir and dam, the lake has filled to
capacity and the spillway has been used 12 times, last spilling in 2005.
In 2018, the City contracted with HDR Engineering, Inc. for
inspection and assessment of the Whale Rock Dam 850-
foot long spillway. The investgation included:
1. Review of design, construction, inspection, analysis,
operation and maintenance, and geologic
information, as provided by City.
2. Detailed visual inspection of the spillway slabs and
walls from upstream of the spillway crest to
downstream of the stilling basin.
3. Video/camera inspection of accessible outfall drains
and heel drains.
4. Geologic inspection of foundation material adjacent
to the spillway.
5. Evaluation of original spillway design versus a modern spillway design.
6. Evaluation of operations, inspection, and surveillance practices.
7. Evaluation of performance of previous repairs.
A report was completed in March 2019 with recommendations including maintenance and repair activities
for the drainage system and further engineering investigations. The City and its Whale Rock partners, Cal
Poly and the California Men’s Colony, will implement corrections as recommended by the California
Department of Water Resources, Division of Safety of Dams.
Temporary Generator and the City’s Stenner Canyon
Water Treatment Plant.
Whale Rock Dam Spillway.
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Pipeline Condition Assessments
During the 2019 Water Year, pipeline condition assessments were completed for the Whale Rock
Reservoir and Salinas Reservoir (Santa Margarita Lake) water transmission pipelines. The condition
assessments used free-swimming electromagnetic inspection technology, shown in the image below, to
locate and identify segments of the pipeline in need of repair. Over 16 miles of 30-inch transmission
pipeline from Whale Rock Reservoir was analyzed. The assessment found that 2,610 segments had no
abnormalities, and 25 segments had varying deficiencies (broken bar wraps or cylinder wall loss). The
Salinas pipeline condition assessment analyzed 1.25 miles of pipeline originally installed in 1940s. Results
of the assessment were described in a May 2019 report revealing 222 of the total 236 segments had no
abnormalities, and 14 segments had varying deficiencies. Funding is programmed to address these
pipeline deficiencies in the 2020-21 fiscal year.
Conceptual image of Electromagnetic Inspection Technology used to assess the
Whale Rock and Salinas Reservoir transmission pipelines.
Sustainable Groundwater Management Act
The use of groundwater contributes to resiliency in the City’s water supply portfolio by offering a potable
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. In May 2017, the City Council approved Resolution 10796
authorizing the City to become a Groundwater Sustainability Agency (GSA) for the San Luis Valley
Groundwater Basin for the area that lies beneath and within the City’s jurisdictional boundaries. In
February 2019, the City Council, acting as the San Luis Valley Basin – City of San Luis Obispo Groundwater
Sustainability Agency, approved the Notification of Intent to initiate development of a Groundwater
Sustainability Plan (GSP) for the San Luis Obispo Valley Groundwater Basin.
The City is working in collaboration 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 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.
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Leak Detection
In September 2019, staff from the City’s Water Distribution
section field tested acoustic correlation equipment by
Echologics on an existing cast iron water main on Bebee Street.
Acoustic sensors were attached to water valves to measure the
speed at which sounds waves travel along the pipe. These
sensors effectively listen to water flowing through the pipe and
can hear when water is escaping through a leak. The location
can then be identified. Using this tool regularly the City will be
able to:
• More accurately locate small leaks, resulting in less
damage to surrounding infrastructure
• Further optimize its capital spending
• Minimize water main breaks, water loss, and damage from leaks
• Better manage aging water infrastructure
The City’s correlator can identify leaks that have not come to the surface yet, and pinpoint leak location
within about two feet. The City’s Water Distribution team is looking forward to utilizing this device to
reduce water loss, find leaks before they create damage, reduce road repair work, and enhance proactive
maintenance of the water distribution system.
Waterline Replacement Projects
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.
During the 2019 Water Year, the City completed replacement of approximately 5,000 lineal feet of
waterline on Pacific (from Nipomo to Walker), Boysen (from Chorro to Hwy. 1), Chorro (from Pismo to
Pacific) and Sierra (from Ella to Bishop) streets at a cost of approximately $2.3 million.
The Casa/Stenner/Murray Waterline Replacement Project proposes replacement of over 3,100 lineal feet
of aged waterline on Casa, Stenner, Murray (from Hathway to Santa Rosa) and the intersections of
Chorro/Meinecke and Chorro/Murray. The construction cost of the project is approximately $2 million.
The waterlines replaced with this project are undersized and deteriorated. Their replacement will
eliminate capacity limitations for Sierra Vista Hospital, reduce the likelihood of service interruptions due
to leaks, and improve water flow for fire protection.
Short-Term Water Sales
At a March 2019 study session, City Council provided direction to staff related to short-term water sales.
A potential recipient of this program may be Cal Poly while the university secures a permanent water
supply specifically related to housing production. Council supported broadening existing policy language
for the City to supply non-potable water (raw water or recycled water) through a short-term agreement
for agricultural purposes. Short-term agreements would be crafted to include provisions for service
interruption or reduction, due to operational issues or climatic events, low reservoir levels, increased
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water demand forecasting, or water quality deterioration. Meaning, during a water shortage emergency,
City water deliveries would be prioritized above those included in a short-term sales agreement.
The City is uniquely positioned to assist Cal Poly in meeting its 2035 Master Plan goals as both a regional
water partner and in support of City goals, particularly as it relates to additional on-campus housing. Cal
Poly currently only has one source of potable water, which is raw water from Whale Rock Reservoir that
is treated at the City’s water treatment plant and delivered to the campus as part of a contract between
the City and Cal Poly. Any contracts for short-term water sales would be brought to the City Council for
consideration.
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 a fifth supplemental source. The supply per source for Water Year 2019 (from October 1, 2018 to
September 30, 2019) is summarized below.
2019 City Water Supply by Source
(in acre feet)
Nacimiento
Reservoir
Whale Rock
Reservoir 2
Recycled
Water
Salinas
Reservoir Groundwater 3 Total City Water
Demand
3,406 350 201 805 0 4,762
71.5% 7.4% 4.2% 16.9% 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 2019.
During Water Year 2019, 71.5 percent of the City’s total water demand was met by Nacimiento Reservoir.
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
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 2019, the City utilized a total of 1,155-acre feet from Salinas and Whale Rock reservoirs,
meeting 24.3 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 2019, the City delivered 201-acre feet of recycled water for
landscape irrigation and construction water. This equates to 4.21 percent
of total City water demand. New recycled water customers include Coast
BMW, HASLO for the Iron Works housing project, and Prado Day Center.
Recycled Water
for Construction
(in acre feet)
2017 2018 2019
19 36 20
Note: Values are rounded.
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Construction water use decreased from 36-acre feet in Water Year 2018 to 20-acre feet in Water Year
2019.
Construction of the Water Resource Recovery Facility (WRRF) Project began in 2019 and will take
approximately three years to complete. When complete, the new technology used at the WRRF will reduce
overall wastewater treatment time by approximately 20 hours, from approximately 28 hours to eight
hours, providing a shortened timeframe for when wastewater comes into the plant and when it can be
sent out into the recycled water system for irrigation use.
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. During Water Year
2019, the City continued its work with a hydrogeologist to site a future well field for a potential
groundwater program expansion. The City received notice from the State Water Resources Control
Board inviting the City to submit a full proposal for the Proposition 1 Groundwater Grant Program for
consideration in 2019. The City was notified in October 2019 that pending negotiation with the State
Board, it will be receiving the $2 million planning-phase grant for installation of monitoring wells and
for monitoring groundwater quality. These are necessary steps in reestablishing the City’s groundwater
program. The planning phase will continue through 2020 with implementation planned for 2021.
III. WATER DEMAND
During Water Year 2019, 60.48 percent of total water use in the City was to support single and multi-
family residential uses, 28.36 percent was to support commercial and other non-residential development,
and 11.16 percent was to support landscape irrigation that is separately metered. Historical water use is
summarized below, as well as corresponding population, per capita use rate, and rainfall. The 2019 per
capita water use was 91 gallons per capita per day (gpcd). Per capita water use is calculated by dividing
total water use 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,
Salinas Dam spillway, February 2019.
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and irrigation. Based on the City’s General Plan Water 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.
Population, Water Use, and Rainfall
Year Population3 Total Water Use
(acre feet)
Per Capita Water Use
(gpcd) Rainfall1,2 (inches)
2010 44,948 5,489 109 36.0
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 46,802 4,762 91 27.1
NOTES:
1. Rainfall for 20 10 through 2012 calendar year sourc e was from Cal Poly CIMIS Weather Station. Rainfall for calendar year
2013 through 2019 was from SLO Reser voir.
2. Rainfall data for 2000-2014 is for the calendar year; 2015-2019 data covers the Water Year (October 1 to September 30).
3. Population data is available at: http://www.dof.ca.gov/Forecasting/Demographics/Estimates/e-1/
The City’s water supply reservoirs are in different watersheds, therefore rainfall at various locations within
San Luis Obispo County benefits the City. During Water Year 2019, three reservoir locations (Rocky Butte,
SLO Reservoir, and Salinas Dam) received more than the annual average. The remaining location, Hwy 46
and W 7 Mile Road, Cambria, CA, received 92 percent of average rainfall.
Water Year 2019 Rainfall Totals
Rainfall Measurement
Location Watershed
Annual
Average
Rainfall
(in inches)
Water Year
2019
Total Rainfall
(in inches)
Water
Year 2019
Percent of
Average
Rocky Butte Nacimiento Reservoir 40 52.40 131%
Hwy 46 and W 7 Mile
Road, Cambria, CA Whale Rock Reservoir 30 27.65 92%
SLO Reservoir City 24 27.10 113%
Salinas Dam Salinas Reservoir 22 33.25 151%
Source: https://wr.slocountywater.org/list.php?sensor_class=11&mode=sensor&cache=1&refresh=off
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IV. WATER RESOURCE AVAILABILITY
The following table summarizes the Water Resource Availability based on Water and Wastewater
Management Element, Section 3. Water availability for 2019 is 10,136-acre feet.
2019 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 244 2018 Annual Usage 3
Siltation from 2010 to 2060 (500) WWME Policy A 4.2.2 4
10,136 2019 Annual 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 is the actual prior year’s usage (calendar year
2018) 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, Section 5, the City accounts for water
supplies necessary to meet three specific community needs:
• Primary water supply
• Reliability reserve
• Secondary water supply
The City’s primary water supply is defined as the amount
of water needed to serve the build-out 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 people. 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 provides a 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 (46,802, 2019 population) at 117
gpcd. The reliability reserve will change over time as the
City’s 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 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 General Plan Water and Wastewater
Management Element, Policy A 5.2.4.
Water supply accounting is summarized in the table below and shown in Appendix A .
2019 Water Supply Accounting (acre feet)
Total Primary Water Supply Reliability Reserve Secondary Water Supply
10,136 7,496 1,227 1,413
In summary, the City maintains a robust water supply portfolio with greater than five years of water
available. Per capita water use (obtained from adding up all water used by visitors, residents, commercial
uses, etc.) decreased during the 2019 Water Year to 91 gallons per capita per day (gpcd) from 100 gpcd
during the 2018 Water Year.
Primary Water Supply
= 117 gpcd x City Build-out Population
= 117 gpcd x 57,200 x 365 day/year x
Acre-Ft/325,851 gal
7,496 Acre-Ft/year
Reliability Reserve
= 117 gpcd x 2019 City Population x
20 percent
= 117 gpcd x 46,802 x 365 day/year x
Acre-Ft/325,851 gal x 20 percent
1,227 Acre-Ft/year
Secondary Water Supply
= Current Annual Availability – Primary
Water Supply – Reliability Reserve
= 10,130 Acre-Ft/yearA – 7,496 Acre-
Ft/year – 1,220 Acre-Ft/year
1,413 Acre-Ft/year
A 2018 Annual Availability
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Appendix A.
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