San Joaquin Valley – Cosumnes
Statistics
- Basin Name
- San Joaquin Valley – Cosumnes
- Basin Number
- 5-022.16
- SGMA Basin Priority
- Medium
- Critically Overdrafted
- No
- Hydrologic Region Name
- San Joaquin River
- Counties
- Amador, Sacramento
Basin Notes
2003: Bulletin 118 basin description
2014: CASGEM basin prioritization – medium
2016: Basin boundary modification requests: accepted with Eastern San Joaquin subbasin 5-022.01 and reviewed, one accepted, one denied for Sacramento Valley – South American 5-021.65
Revised basin boundaries description
2018: Draft basin priority – medium. Ground water level comments:
- 1) CASGEM/WDL/GWIDS: Longterm hydrographs show groundwater level decline. Source: DWR 2)
- North San Joaquin Water Conservation District Conjunctive Use Plan – Tracy Lake Groundwater Recharge Project, November 3, 2016 recognizes that Cosumes GWB already in overdraft conditions: “The plan also must address whether and how placing water to underground storage and subsequently withdrawing the water, under Permit 10477 will prevent additional overdraft in the Eastern San Joaquin and Cosumnes groundwater subbasins…”
2019: Basin boundary modification request denied. Per DWR: “The boundary modification would revise a portion of the shared boundary between the Cosumnes and South American subbasins to expand and incorporate the jurisdictional areas of Sloughhouse Resource Conservation District and (SRCD) and Omochumne-Hartnell Water District (OHWD). The revised boundary would then follow the northern boundaries of the SRCD and OHWD jurisdictional boundaries. Four letters of support and two letters of opposition are associated with the request. Letters of opposition were provided by the Sacramento Central Groundwater Authority and the City of Sacramento. Five public comments (3 support, 2 oppose) were submitted on draft decision to deny the modification. The requesting agency did not sufficiently demonstrate the proposed modification would result in improved groundwater management. The request does not fully meet the requirements of the regulations.” Phase 2 draft priority: medium.
2022: January 27 – Groundwater Sustainability Plan (GSP) submitted to Department of Water Resources (DWR)
2023: October 26 – GSP approved by DWR
At-A-Glance

California Water Library Documents About This Basin
Replenishing Groundwater in the San Joaquin Valley: 2024 Update
Public Policy Institute of California (PPIC) | June 6th, 2024
Strategies to replenish groundwater basins—long used in some areas of the San Joaquin Valley—have increasingly come into focus as the region seeks to bring its overd
Groundwater sustainability and land subsidence in California’s Central Valley
Water (MDPI) | April 22nd, 2024
The Central Valley of California is one of the most prolific agricultural regions in the world. Agriculture is reliant on the conjunctive use of surface-water and groundw
Statement of Findings regarding the Approval of the San Joaquin Valley – Cosumnes Subbasin Groundwater Sustainability Plan
California Department of Water Resources (DWR) | October 26th, 2023
Thousands of domestic and public supply wells face failure despite groundwater sustainability reform in California’s Central Valley
Nature Portfolio (Springer Nature) | September 8th, 2023
Comparing Domestic and Public-Supply Groundwater Quality in the Northern San Joaquin Valley, 2019: California GAMA Priority Basin Project
U.S. Geological Survey (USGS) | June 5th, 2023
Analysis of construction data for wells included in the comparative assessment indicated that, although depth to top of perforations are comparable for domestic and publi
Comparing domestic and public-supply groundwater quality in the northern San Joaquin Valley, 2019—California GAMA Priority Basin Project
U.S. Geological Survey (USGS) | June 5th, 2023
Groundwater quality in the Northern San Joaquin Valley region of California was studied as part of California State Water Resources Control Board (SWRCB) Groundwater Ambi
Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California
Journal of Hydrology (Elsevier) | December 5th, 2022
The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contami
Subsurface water flux in California's Central Valley and its source watershed from space geodesy
American Geophysical Union (AGU) | September 29th, 2022
We combine measurements from Global Positioning System positioning and Gravity Recovery and Climate Experiment gravity to infer change in water components in Central Vall
Status and understanding of groundwater quality in the Sacramento Metropolitan Domestic-Supply Aquifer study unit, 2017—California GAMA Priority Basin Project
U.S. Geological Survey (USGS) | May 26th, 2022
Groundwater quality in the Sacramento Metropolitan Domestic-Supply Aquifer study unit (SacMetro-DSA) was studied from August to November 2017 as part of the second phase
Post-Drought Groundwater Storage Recovery in California's Central Valley
American Geophysical Union (AGU) | October 5th, 2021
California's Central Valley has experienced chronic groundwater depletion over the past few decades, the rate of which was amplified by droughts in 2007–2009 and 2012?
Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought
American Geophysical Union (AGU) | September 1st, 2021
It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood.
Geologic Influences on the Quality of Groundwater Used for Domestic Supply in the Northern Sierra Nevada Foothills
U.S. Geological Survey (USGS) | May 25th, 2021
Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the
Base of fresh water, groundwater salinity, and well distribution across California
National Academy of Sciences (NAS) | December 9th, 2020
The depth at which groundwaters transition from fresh to more saline—the “base of fresh water”—is frequently used to determine the stringency and types of measure