OAKLAND, March 3, 2023
Regional water partners’ first aquifer recharge and groundwater test a success
Water agencies in California’s Central Valley and East Bay took a major step forward in February on a joint pilot project to diversify water supplies, enhance drought resilience and restore a depleted aquifer through groundwater recharge.
For the first time, the East Bay Municipal Utility District (EBMUD) extracted groundwater banked deep below farmland in San Joaquin County into the utility’s Mokelumne aqueducts, which convey surface water from Pardee Reservoir in the Sierra Nevada foothills to customers in the East Bay.
This extraction was a key step for DREAM – short for Demonstration Recharge, Extraction and Aquifer Management – a pilot project involving EBMUD, North San Joaquin Water Conservation District, San Joaquin County, and Eastern Water Alliance. The unique urban-agricultural partnership is designed to improve water supply reliability for both San Joaquin County farmers and EBMUD customers in Alameda and Contra Costa counties while recharging the critically over-drafted Eastern San Joaquin County Groundwater Basin.
DREAM is the result of years of negotiations and trust-building between water agencies to find mutually beneficial solutions to emerging water challenges.
Under the pilot project, EBMUD is providing up to 1,000 acre-feet of surface water diverted from the Mokelumne in wet years to avoid the need for farmers to pump groundwater from the area’s depleted aquifer. In exchange, EBMUD receives a credit to withdraw up to half as much water as it previously delivered to farmers. The result will be a net gain in groundwater to replenish the aquifer, growers receiving the water they need to irrigate crops, and greater diversification of EBMUD’s water supplies.
“The DREAM project is a great example of how both urban and ag water users in our region can work together to improve groundwater management and increase dry-year water supplies,” said San Joaquin County Board of Supervisors Chairman Robert Rickman. “This project serves as a model for other regions to follow, and I am certain that the partnerships that have been made possible will enable us to overcome even greater water challenges that lie ahead.”
EBMUD first delivered surface water to growers in 2018 and 2019. This February, North San Joaquin Water Conservation District provided EBMUD with nearly 40 acre-feet of groundwater over 13 days, or about 1 million gallons a day. That is a small percentage of the roughly 160 million gallons of water EBMUD delivers daily to customers, but it represents a significant milestone as EBMUD works to expand its water supply portfolio and increase resilience against drought and other challenges exacerbated by climate change.
“The teamwork and trust demonstrated by our partners to implement the DREAM project addresses complex water supply and environmental challenges,” said EBMUD Board President Andy Katz. “As EBMUD celebrates a century of service, DREAM is an example of our continued commitment to innovation and the infrastructure investments we need to build a resilient water system for the future.”
This is the first time EBMUD has incorporated groundwater into its Mokelumne water supply. EBMUD treated the blended water at its water treatment plants, and extensive water quality testing throughout the process ensured the water blend met or surpassed all state and federal drinking water safety standards. In addition, San Joaquin County monitored groundwater levels near the DREAM extraction well to verify the aquifer was not negatively impacted by the pumping.
The DREAM project partners expect to complete this pilot in March 2026 and are discussing concepts for a larger-scale groundwater banking program.
“To solve our local water supply challenges, we have to think regionally about how to make the system work better for all involved by utilizing the unique assets of each project partner,” said North San Joaquin Board President Joe Valente. “As a district, we have learned so much with the DREAM project and are excited to take the concept to the next level.”