HomeMy WebLinkAboutCC 2025-01-28_09f 2024 Calendar Year 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: Calendar Year 2024 Water Supply and Demand Update
DATE: January 28, 2025
RECOMMENDATION:
Receive and file the Calendar Year 2024 Water Supply and Demand Update.
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, 1,323 Acre Feet of groundwater entitlement from the Santa Maria
River Groundwater Basin, and 160 Acre Feet from the City’s wells that draw from the
Pismo formation.
The predicted water use for 2024/2025 is 2,100 Acre Feet.
In 2024, the City’s water use was 2,023.6 Acre Feet with a per capita use of 100 gallons
per day/per person. The residential per capita use was 78 gallons per day/per person.
There was a total of 18.3 inches of rainfall at the City Corporation Yard gauge in 2024.
ANALYSIS OF ISSUES:
As of January 13, 2025, the United States Drought Monitor shows San Luis Obispo
County abnormally dry. Lopez Lake is 91.6% (45,327 Acre Feet) as of January 13, 2025.
The deep well index for the f ourth quarter of 2024 was completed on October 15, 2024,
and is 11.51 feet above sea level, which is 4.01 feet above the threshold value. The
current deep well index is 0.24 feet lower than July 2024 and 0.56 feet higher than
October 2023.
ALTERNATIVES:
The following alternatives are provided for the Council’s consideration:
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Item 9.f.
City Council
Calendar Year 2024 Water Supply and Demand Update
January 28, 2025
Page 2
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.
DISADVANTAGES:
No disadvantages noted at this time
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 December 2024
2. Lopez Reservoir Storage Projection
3. Yearly Water Use Comparison
4. Deep Well Index Levels
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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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