CC 2024-11-26_09f Monthly Water Supply and Demand UpdateItem 9.f.
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: November 26, 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 October 2024 was 194.3 Acre Feet. Attachment 3
has been revised to show the comparison of the previous year’s use. November 2022
through October 2023 vs. the current years use, November 2023 through October 2024.
The increase is directly related to rainfall totals over the two years.
The per capita monthly water use for October 2024 is 114 gallons per day/per person.
The residential per capita use was 89 gallons per day/per person. There was a total of
0.0 inches of rainfall in the City in October 2024.
ANALYSIS OF ISSUES:
The United States Drought Monitor, as of November 12, 2024, shows San Luis Obispo
County is not in a drought. Rainfall for the period of July 1, 2024, through November 12,
2024, is 0.11 inches at the Corporation Yard rain gauge. Lopez Lake is 92% capacity as
of November 12, 2024.
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Item 9.f.
City Council
Monthly Water Supply and Demand Update
November 26, 2024
Page 2
The deep well index for the fourth quarter of 2024 was completed on October 15, 2024,
and is 11.51 feet above sea level, which is 4.01 feet abo ve the threshold valve. The
current deep well index is 0.24 feet lower than July 2024, a nd 0.56 feet higher than
October 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 October
2. Lopez Reservoir Storage Projection
3. Previous Year Water Use Comparison
4. Deep Well Index Levels for 4th Quarter
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277.21885.694298.62031.610105001000150020002500Commercial Usage Portion of Production Acre Feet Production Usage (gpcd)Previous Year Water Use ComparisonAttachment 3Previousyear use Nov 2022/Oct 2023 Current year use Nov 2023/Oct 2024Page 127 of 243
HISTORICAL FOURTH QUARTER DEEP WELL INDEX LEVELS
Northern Cities Management Area
San Luis Obispo County, California
P:\672-Northern Cities Management Area\_Grapher Figures\Quarterly Rpt Figs Fig 6 NCMA_Q4_Deep_Well_Index_v2
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025
-5
0
5
10
15
20
Water Elevation, feet NAVD88Deep Well Index
Threshold: 7.5 feet
FIGURE 6Deep Well Index is the synoptic average of groundwater elevations
in the deep wells of Sentry Well clusters 24B,30F, and 30N.
"Approximate" Deep Well Index elevations are based on
non-synoptic measurments, made during the same quarter.
Attachment 4
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