CC 2024-08-27_09c Monthly Water Supply and Demand UpdateItem 9.c.
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: August 27, 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 groundwater
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.
As shown in Attachment 3, the monthly water use for the City in July 2024, was 212.5
Acre Feet, compared to the previous 5 year average of 218.3 Acre Feet. This
demonstrates that water conservation is occurring. The per capita monthly water use for
July 2024 is 124 gallons per day/per person. The residential per capita use was 96 gallons
per day/per person. There was a total of 0.0 inches of rainfall in the City in July 2024.
Attachment 3 shows current monthly water use as compared to the previous five-year
average for the month. Staff has provided a “Commercial Usage Portion of Production”
as an additional information point highlighting conservation efforts.
ANALYSIS OF ISSUES:
The United States Drought Monitor, as of August 13, 2024, shows San Luis Obispo
County is not in a drought. Rainfall for the period of July 1, 2023, through August 13 th,
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Item 9.c.
City Council
Monthly Water Supply and Demand Update
August 27, 2024
Page 2
2024, is 0.0 inches at the Corporation Yard rain gauge. Lopez Lake is at 96.8 % capacity
as of August 13th, 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 to 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 July
2. Lopez Reservoir Storage Projection for July
3. Monthly Water Use Comparison for July
4. Deep Well Index Levels for 3rd quarter
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HISTORICAL THIRD 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_Q3_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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