HomeMy WebLinkAbout01/15/2019, Fowler - City of SLO_ 2018 Water Resource Status Report1
From:Fowler, Xzandrea
Sent:Wednesday, January 16, 2019 10:16 AM
To:CityClerk
Cc:Metz, Jennifer
Subject:City of SLO: 2018 Water Resource Status Report
Attachments:2018 Water Resources Status Report.pdf
Good morning Planning Commissioners,
Last night the City Council approved the 2018 Water Resource Status Report. The Report provides an
overview and update on the City’s water resources, from October 1, 2017 through September 30, 2018. The
Report is attached for your review and here is the link to the City Council staff report .
This Report is being forwarded to the Planning Commission for informational purposes only, no action is
required.
If you have any questions about the Report, please contact Jennifer Metz, Utilities Project Manager, at
jmetz@slocity.org or (805) 781-7239.
Xzandrea Fowler
Deputy Director Community Development
Community Development
Long Range Planning
919 Palm Street, San Luis Obispo, CA 93401
E XFowler@slocity.org
T 805.781.7274
slocity.org
2018 Water Resources Status Report
For the Time Period October 1, 2017 through September 30, 2018
Prepared by the Water Division of the City of San Luis Obispo, Utilities Department
City of San Luis Obispo
2018 Water Resources Status Report
Page 2
The City’s 2018 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, 2017 through September 30, 2018), the 12-month period for which precipitation totals
are measured designated by the calendar year in which it ends. This report for Water Year 2018 is organized
as follows:
I. Water Projects and Policy Update
II. Water Supply
III. Water Demand
IV. Water Resource Availability
V. Water Supply Accounting
I. WATER PROJECTS AND POLICY UPDATE
2018 Update to General Plan, Water and Wastewater Management Element
In May 2018, the City Council approved text amendments to the City’s Water and Wastewater
Management Element (WWME) of the General Plan. The primary focus of the amendment was to provide
updated water supply information from the City’s safe annual yield model. No policy changes were made
as part of the amendment.
The City defines the terminology “safe annual yield” as the amount of water which can be reliably
withdrawn annually from coordinated operation of Salinas and Whale Rock Reservoirs. A previous key
assumption used in the model was the "controlling drought period" from 1986-1991. The 2018 update to
the safe annual yield model added data from the most recent drought that ended in 2016 consistent with
WWME program A 3.3.2 and analyzed three climate change scenarios. Based on the updated modeling
and analysis of climate change scenarios, safe annual yield from Salinas and Whale Rock Reservoirs was
reduced from 6,940-acre feet to 4,910-acre feet as part of the amendment.
Change in Annual Water Supply Availability
2017 Annual
Availability
2018 Annual
Availability
Salinas Reservoir and
Whale Rock Reservoir 6,940 AF 4,910 AF1
Nacimiento Reservoir 5,482 AF 5,482 AF
Recycled Water 193 AF 238 AF
Siltation to 2060 (500 AF) (500 AF)
TOTAL 12,115 AF 10,130 AF
NOTES:
1. Reflects reduction in Safe Annual Yield as determined by the City’s model.
2. Water supply accounting data is in “AF” or acre feet.
Although this is a significant reduction in the safe annual yield from these reservoirs, the City has a multi-
source water supply to meet the City’s future water demand. Data provided in Section IV of this report on
Water Resource Availability, reflects the updated WWME.
City of San Luis Obispo
2018 Water Resources Status Report
Page 3
Water Resiliency Planning – Water Energy Efficiency Project
The City declared Climate Action a Major City Goal in the 2017-19 Financial Plan and identified objectives
focused on energy efficiency and greenhouse gas reductions within City facilities, such as the City’s Water
Treatment Plant. In April, the City Council approved Resolution 10878 authorizing participation in Pacific
Gas and Electric’s Sustainable Solutions Turnkey Program for the Water Energy Efficiency Project. The
Project is analyzing both the use of photovoltaic panels and a hydropower turbine that would convert the
energy in the high-pressure water line from Nacimiento Reservoir into electricity. The electricity
generated would offset the Water Treatment Plant’s overall power demand (Water = Energy). The Project
is also assessing pump efficiencies within the Water Treatment Plant, the primary disinfection system,
water quality in storage tanks, water distribution main inter-ties between service zones, and settings of
related controls needed for control system (SCADA-Supervisory Control and Data Acquisition) integration.
Recommendations will be presented to the City Council in 2019 on alternative energy generation
opportunities as well as replacing aging infrastructure in a holistic manner from the surface water source,
to the treatment plant, and within the distribution system.
Water = Energy
Water Energy Efficiency Project, 2018.
City of San Luis Obispo
2018 Water Resources Status Report
Page 4
2018 State Legislation on Water Conservation and Drought Planning
The California State Legislature (Legislature) enacted two
policy bills in 2018 – Senate Bill (SB) 606 and Assembly
Bill (AB) 1668 – to establish a new foundation for long-
term improvements in water conservation and drought
planning to adapt to climate change and the resulting
longer and more intense droughts in California. These
two bills amend existing law to provide expanded and
new authorities and requirements to enable permanent
changes and actions for those purposes, improving the
state's water future for generations to come.
In August 2018, the State made the Public Review Draft
of Making Water Conservation a California Way of Life
available addressing the four primary goals in Executive
Order B-37-16 and the 2017 Framework:
(1) use water more wisely,
(2) eliminate water waste,
(3) strengthen local drought resilience, and
(4) improve agricultural water use efficiency
and drought planning.
Goals 1 through 3 will apply to the City’s water planning.
The bills include changes in Urban Water Management
Plan (UWMP) preparation requirements as well as
schedule and content provisions for the most critical
reporting requirement – the annual water use report.
Under the new authorities and requirements, the City
would be required to prepare, adopt, and submit a Water
Shortage Contingency Plan (WSCP) and conduct a
Drought Risk Assessment (DRA) every five years in
addition to conducting an annual water supply and
demand assessment. The City already has adopted a
WSCP and prepares this WRSR annually. However, these
documents will need to align with new State
requirements with the 2020 update to the City’s UWMP.
Making Water Conservation a California Way of Life is
available at the following link:
https://water.ca.gov/-/media/DWR-Website/Web-
Pages/Programs/Water-Use-And-Efficiency/Make-Water-
Conservation-A-California-Way-of-Life/Files/PDFs/Primer-of-
2018-Legislation-on-Water-Conservation-and-Drought-
Planning.pdf
City of San Luis Obispo
2018 Water Resources Status Report
Page 5
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
supplies recycled water for landscape irrigation and construction water.
Groundwater serves as a fifth supplemental source. The supply per
source for Water Year 2018 (from October 1, 2017 to September 30,
2018) is summarized below.
2018 City Water Supply by Source (Acre Feet)
Nacimiento
Reservoir
Whale Rock
Reservoir 2
Recycled
Water
Salinas
Reservoir Groundwater 3 Total City Water
Demand
3,848 410 244 723 0 5,225
73% 8% 5% 14% 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 2018.
During Water Year 2018, 73 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 which also sits as the Board of Directors for the Flood Control District.
During Water Year 2018, the City utilized a total of 1,133-acre feet from Salinas and Whale Rock reservoirs,
meeting 22 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 the Salinas
Reservoir and related water delivery facilities. The City provides the 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 2018, the City delivered 244-acre feet of recycled water for
landscape irrigation and construction water, up from 229-acre feet in Water
Year 2017 and five percent of total City water demand. New recycled water
customers include the Homeless Services Center located on Prado Road and
the new Park and Ride located on Calle Joaquin. Construction water use
increased from 19-acre feet in Water Year 2017 to 36-acre feet in Water
Year 2018.
The design phase for the City’s Water Resource Recovery Facility (WRRF) Project continued through Water
Year 2018. Construction of the Project is planned to begin in 2019 and will take approximately three years.
When complete, the new technology used at the WRRF will reduce overall treatment time from
approximately 28 hours to eight hours.
City of San Luis Obispo
Water Supply Sources
✓ Nacimiento Reservoir
✓ Whale Rock Reservoir
✓ Recycled Water
✓ Salinas Reservoir
✓ Groundwater
Recycled Water
for Construction
(in acre feet)
2017 2018
19 36
Note: Values are rounded.
City of San Luis Obispo
2018 Water Resources Status Report
Page 6
With increasing demand for recycled water, the City has developed a recycled water production model to
simulate future recycled water supply and demand. This model will assist in developing parameters for
how much recycled water is available for in-City customers and excess recycled water that may be
available for outside-City deliveries.
Although the City stopped using groundwater for potable purposes in April 2015, groundwater wells
remain in an operable, stand-by position should the use of groundwater be required. During Water Year
2018, the City continued its work with a hydrogeologist to site a future well field for a potential
groundwater program expansion. The City submitted a Concept Proposal in August 2018, to be
considered for the Proposition 1 Groundwater Grant Program. The City received notice from the State
Water Resources Control Board invit ing the City to submit a full proposal for consideration in 2019.
The City’s permit program for the use of the Corporation Yard well expired December 31, 2018 and the
well will be closed to the public starting January 1, 2019. After several years of close coordination with
County of San Luis Obispo Public Works staff, a County-owned potable water filling station is scheduled
to open to the public on January 1, 2019. This filling station is intended to supply the needs of those
currently utilizing the City’s Corporation Yard well.
III. WATER DEMAND
During Water Year 2018, 62 percent of total water use in the City was to support single and multi-family
residential uses, 24 percent was to support commercial and other non-residential development, and 14
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 2018 per capita water
use was 100 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, 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)
2009 44,829 6,134 122 18.9
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
NOTES:
1. Rainfall for 20 09 through 2012 calendar year source was from Cal Poly CIMIS Weather Stati on. Rainfall for calendar year
2013 through 2018 was from SLO Reser voir.
2. Rainfall data for 2009 through 2014 is for the calendar year; 2015 through 2018 data covers the Water Year (October through
September).
3. Population data is available at: http://www.dof.ca.gov/Forecasting/Demographics/Estimates/e-1/
City of San Luis Obispo
2018 Water Resources Status Report
Page 7
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 2018, the majority of area rainfall occurred
in March. All reservoir locations received less than the annual average during Water Year 2018.
Water Year 2018 Rainfall Totals
Rainfall Measurement
Location Watershed
Annual Average
Rainfall
(in inches)
Water Year 2018
Total Rainfall
(in inches)
Rocky Butte Nacimiento Reservoir 40 29.4
Hwy 46 and W 7 Mile Road,
Cambria, CA Whale Rock Reservoir 30 16.9
SLO Reservoir City 24 12.9
Salinas Dam Salinas Reservoir 22 12.3
Source: https://wr.slocountywater.org/list.php?sensor_class=11&mode=sensor&cache=1&refresh=off
IV. WATER RESOURCE AVAILABILITY
The following table summarizes the Water Resource Availability based on Water and Wastewater
Management Element, Section 3. Water availability for 2018 is 10,130-acre feet.
2018 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 238 2017 Annual Usage 3
Siltation from 2010 to 2060 (500) WWME Policy A 4.2.2 4
10,130 2018 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 recycled water usage
(calendar year 2017) 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.
City of San Luis Obispo
2018 Water Resources Status Report
Page 8
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 (46,548, 2018 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. The amendment to the City’s WWME to
reflect the update to the City’s Safe Annual Yield model, discussed in Section I of this report, led to the
reduction in the City’s available secondary water supply for Water Year 2018.
Water supply accounting is summarized in the table below .
2018 Water Supply Accounting (acre feet)
Total Primary Water Supply Reliability Reserve Secondary Water Supply
10,130 7,496 1,220 1,414
In summary, despite a significant reduction in safe annual yield from the combined operation of Whale
Rock and Salinas Reservoirs, 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.) has increased to 100 gallons per capita per day (gpcd) from 95 gpcd the prior year.
Recycled water use continues to rise over time.
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 City Population x 20 percent
= 117 gpcd x 46,548 x 365 day/year x
Acre-Ft/325,851 gal x 20 percent
1,220 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
1,414 Acre-Ft/year
A 2018 Annual Availability