HomeMy WebLinkAboutCC 2025-02-25_09d Monthly Water Supply and Demand UpdateItem 9.d.
MEMORANDUM
TO: City Council
FROM: Bill Robeson, Assistant City Manager/Public Works Director
BY: Shane Taylor, Utilities Manager
SUBJECT: Monthly Water Supply and Demand Update
DATE: February 25, 2025
RECOMMENDATION:
Receive and file the Monthly Water Supply and Demand Update.
IMPACT ON FINANCIAL AND PERSONNEL RESOURCES:
Approximately two (2) hours of staff time is required to prepare the report.
BACKGROUND:
The City of Arroyo Grande’s water entitlements are calculated on a water year that begins
April 1st. The current water supply for water year 2024/2025 includes 2,290 Acre Feet
from Lopez Reservoir, the current modeled, safe yield is 357 Acre Feet of ground water
from the Santa Maria River Groundwater Basin, with an entitlement of 1,323 Acre Feet.
An additional 160 Acre Feet of groundwater is available from the Pismo formation.
The predicted water use for the 2024/2025 water year is 2,100 Acre Feet.
The monthly water use for the City in January 2025 was 156.2 Acre Feet. Attachment 3
has been revised to show the comparison of the previous year’s use. February 2023
through January 2024 vs. the current years use, February 2024 through January 2025.
The increase is directly related to rainfall totals over the two years.
The per capita monthly water use for January 2025 is 91 gallons per day/per person. The
residential per capita use was 71 gallons per day/per person. There was a total of 0.2
inches of rainfall in the City in January 2025.
ANALYSIS OF ISSUES:
The United States Drought Monitor, as of February 6, 2025, shows San Luis Obispo
County is in moderate drought. Rainfall for the period of July 1, 2024, through February
6, 2025, is 4.5 inches at the Corporate Yard rain gauge. Lopez Lake is 91.2% as of
February 10, 2025.
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Item 9.d.
City Council
Monthly Water Supply and Demand Update
February 25, 2025
Page 2
The deep well index for the first quarter of 2025 was completed on January 22, 2025, and
is 10.78 feet above sea level, which is 3.28 feet above the threshold valve. The current
deep well index is 0.73 feet lower than October 2024, and 1.55 feet lower than January
2024.
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. The County is
preparing updated projections that reflect the increased release rate. The impact on
Lopez Lake storage with this release level will be shown in next month's Monthly Water
Supply and Demand Report to the Council.
The increased release rate does not currently impact the City's contract entitlement (how
much water the City receives) from Lopez Lake. The County has appealed the preliminary
injunction. The City and all other Zone III contractors will work with the County to assess
and report the impacts on our water supply from Lopez Lake until the litigation is resolved.
ALTERNATIVES:
The following alternatives are provided for the Council’s consideration:
1. Receive and file the report, or
2. Provide other directions for staff.
ADVANTAGES:
The report provides the City Council and the public with the current and projected
conditions of our water supply and demand.
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 Operations Report for January
2. Lopez Reservoir Storage Projection
3. Previous Year Water Use Comparison
4. Deep Well Index Levels for 1st Quarter
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