San Joaquin Valley – Cosumnes

Statistics

Basin Name

Basin Number

5-022.16

SGMA Basin Priority

Medium

Critically Overdrafted

Hydrologic Region Name

San Joaquin River

Counties

Amador, Sacramento

Adjacent Basins

Sacramento Valley - South American 5-021.65, San Joaquin Valley - Eastern San Joaquin 5-022.01,

At-A-Glance

Located in California’s San Joaquin River hydrologic region, the San Joaquin Valley – Cosumnes is 210,275.92 acres in size. This Medium priority basin is home to an estimated 49,546 people (2010 value), which have been at a rate of 11.

San Joaquin Valley – Cosumnes is a(n) basin with approximately 3140 wells, of which approximately 30 are water supply wells. Groundwater accounts for approximately 87 percent of the basin’s water supply.

Source: CA DWR

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.