HomeMy WebLinkAboutCC 2026-01-27_09i 2025 Water Supply and Demand Update Item 9.i.
MEMORANDUM
TO: City Council
FROM: Bill Robeson, Assistant City Manager/Director of Public Works
BY: Shane Taylor, Utilities Manager
SUBJECT: Calendar Year 2025 Water Supply and Demand Update
DATE: January 27, 2026
RECOMMENDATION:
Receive and file the Calendar Year 2025 Water Supply and Demand Update.
IMPACT ON FINANCIAL AND PERSONNEL RESOURCES:
Approximately two (2) hours of staff time are required to prepare the report.
BACKGROUND:
The City of Arroyo Grande’s water entitlements are calculated on a water year that began
April 1, 2025. The current water supply 2025 -26 includes:
2,290 Acre Feet (AF) from Lopez Lake Reservoir/Lopez contract entitlement.
The current modeled safe yield is 357 AF of groundwater from the Santa Maria
River Groundwater Basin, with an entitlement of 1,323 AF.
An additional 160 AF of groundwater is available from the Pismo formation from
the existing City well system.
In addition to the annual Lopez Lake Reservoir contract entitlement, the City will have
689.69 AF of stored Lopez water, which is unused entitlement from water year 2024-25.
The City also previously accepted an offer to purchase 470.33 AF of surplus Lopez water.
The surplus water cost is $55,146.74 or $117.14 per AF.
The total supply from Lopez Lake Reservoir for this water year is 3,450 AF. The predicted
water use for the 2025-26 water year is 2,200 AF.
In calendar year 2025, the City’s water use was 2070.4 AF. Th e overall per capita use
was 102 gallons per day. The residential per capita use was 79 gallons per day. There
was a total of 16.6 inches of rain at the Corp Yard gauge in 2025.
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Item 9.i.
City Council
Calendar Year 2025 Water Supply and Demand Update
January 27, 2026
Page 2
ANALYSIS OF ISSUES:
As of January 13, 2026, the USDA Drought Monitor reports S an Luis Obispo County as
normal. Lopez Lake has 83.5% capacity (41,367 AF). The deep well index for the fourth
quarter of 2025 was completed on October 21, 2025. The index level was 10.54 feet
above sea level, which is 3.04 feet above the threshold value. The current deep well index
is 1.09 feet lower than July 2025 and 0.97 feet lower than October 2024.
In the current water year, the City took delivery of all stored and surplus water totaling
1,160 AF. The use of this water prevented it from possibly spil ling and being lost. It is
estimated that 1,500 AF of unused entitlement will be available for storage at the end of
the current water year, March 31, 2026.
On January 15, 2025, in response to a preliminary injunction issued by the United States
District Court to the County of San Luis Obispo, Lopez Lake downstream releases were
increased from 2.0 million gallons per day to 5.1 million gallons per day. This release rate
was in place until December 29, 2025.
The 9th District Court of Appeals overturned the preliminary injunction and returned the
water releases to the interim downstream release rate schedule. The current release rate
on January 14, 2026, was 4.8 cubic feet per second (cfs) or 3.1 million gallons per day.
A gradual increase in the release process to former rates is necessary to monitor creek
conditions. The target rate is 3.8cfs or 2.5 million gallons per day by the end of January
2026.
The City and all other Zone 3 contractors will continue to work with the County to assess
and report on the impact on our water supply from Lopez Lake until the litigation is
resolved. However, the significant costs of the past and ongoing litigation and future
improvements will be shared by the ratepayers of the City and other Zone 3 member
agencies.
To keep the community informed of the current status of the litigation and the City’s water
system, staff developed a webpage where updates will be published. The webpage can
be accessed at www.arroyogrande.org/lopezlakelitigation1.
Council Goals Workplan
In the current Council Goals workplan for Fiscal Year 2025 -27, under the Council Goal of
“Achieve Water Resilience,” the Council has directed staff to Pursue 2026 State Water
Ballot Measure, with the specific subtask to Seek Council approval on placing a
November Ballot Measure. It is anticipated that this item will be brought to the Council for
direction in the near future.
1 https://www.arroyogrande.org/889/Lopez-Lake-Water-Release-Litigation/lopezlakelitigation
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Item 9.i.
City Council
Calendar Year 2025 Water Supply and Demand Update
January 27, 2026
Page 3
AL TERNATIVES:
The following alternatives are provided for the Council’s consideration:
1. Receive and file the report, or
2. Provide other directions to staff.
ADVANTAGES:
The report provides the City Council and the public with the current and projected water
supply and demand conditions.
ENVIRONMENTAL REVIEW:
No environmental review is required for this item.
PUBLIC NOTIFICATION AND COMMENTS:
The Agenda was posted at City Hall and on the City’s website in accordance with
Government Code Section 54954.2.
ATTACHMENTS:
1. Monthly Operation Report for December 2025
2. Lopez Lake Reservoir Storage Projections
3. Previous Year Water Use Comparison
4. Deep Well Index Levels for 4th Quarter
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