CC 2024-10-22_09e Monthly Water Supply and DemandItem 9.e.
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: October 22, 2024
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 September 2024 was 210.9 Acre Feet. Attachment
3 has been revised to show the comparison of the previous year’s use, October 2022
through September 2023 vs. the current years use, October 2023 through September
2024. The increase is directly related to rainfall totals over the two years.
The per capita monthly water use for September 2024 is 127 gallons per day/per person.
The residential per capita use was 99 gallons per day/per person. There was a total of
0.0 inches of rainfall in the City in September 2024.
ANALYSIS OF ISSUES:
The United States Drought Monitor, as of October 11, 2024, shows San Luis Obispo
County is not in a drought. Rainfall for the period of July 1, 2024, through October 11,
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Item 9.e.
City Council
Monthly Water Supply and Demand Update
October 22, 2024
Page 2
2024, is 0.0 inches at the Corporation Yard rain gauge. Lopez Lake is 93.9% capacity as
of October 11, 2024.
The deep well index for the third quarter of 2024 was completed on July 3, 2024, and is
11.57 feet above sea level, which is 4.07 feet above the threshold value. The current deep
well index is 0.66 feet lower than April 2024, and 6.23 feet higher than July 2023.
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 September
2. Lopez Reservoir Storage Projection for September
3. Monthly Water Use Comparison for September
4. Deep Well Index Levels for 3rd Quarter
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274.61868.393296.5201710005001000150020002500Commercial Usage Portion of Production Acre Feet Production Usage (gpcd)Previous Year Water Use ComparisonAttachment 3Previousyear use Oct 2022/Sept 2023 Current year use Oct 2023/Sept 2024Page 120 of 135
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