For nearly a century, agricultural and urban water demands in most of Eastern San Joaquin County have been met with groundwater. Over the past several decades, the amount of groundwater pumped exceeded natural recharge, lowering groundwater levels as much as 150 feet, threatening water supply to the region, including the Stockton metropolitan area. As groundwater levels dropped, the intrusion of saline water from areas below the Sacramento-San Joaquin River Delta, rendering groundwater unsuitable for domestic use in some areas.

With projections showing that water demands will continue to exceed available supplies, local water districts and agencies have concluded that replacement water supplies must be developed to reduce the groundwater overdraft and the eastward migration of salinity. A potential approach includes recharging flood-season and excess irrigation water supplies.

Prior to any commitment of resources to a long-term groundwater recharge program, an initial site screening and percolation (infiltration) test must be completed for each potential recharge site. Sites would be selected to minimize environmental impact and maximize the potential for groundwater recharge. The temporary ponding would provide seasonal habitat for migratory birds and other animals.

As a result, The Corps of Engineers is conducting a feasibility study focused on regional groundwater recharge opportunities.

As an initial step, the study team reviewed existing soil, geology, land use, water use, and groundwater information and identified conditions that influence recharge effectiveness.

The study team reviewed this information and identified candidate sites for recharge testing. Candidate test sites were assessed based on their ability to provide representative information that could be applied regionally. Four sites were selected for pilot-scale recharge testing from an initial list of 15 candidate sites.

Over the next several years, sites will be screened and tested for percolation to determine suitability for directing flood-season and excess irrigation water supplies onto these limited areas. The initial goal of the program is to obtain through purchase, lease, or other agreements 25-30 parcels totaling 1,200 acres for the purpose of direct groundwater recharge.

The first of such tests is the Farmington Groundwater Recharge Demonstration Project – Site #1 – SJAFCA Detention Basin #1, San Joaquin County, California.

Demonstration Project

Farmington Groundwater Recharge Demonstration Project – Site #1 – SJAFCA Detention Basin #1, San Joaquin County, California.


Site #1

Environmental Assessment

Contact Information

For more information on Farmington,
please contact us at the following:



Mailing Address:
U.S. Army Corps of Engineers,
Sacramento District
Farmington Project
1325 J Street, Room 1513
Sacramento, CA 95814