The DREAM Project is a visionary interregional pilot groundwater banking effort that improves water supply reliability and resiliency in both San Joaquin County and the East Bay, while also providing San Joaquin County with an additional water source and funding to protect the Eastern San Joaquin (ESJ) Subbasin. DREAM is being conducted by San Joaquin County, North San Joaquin Water Conservation District (NSJWCD), Eastern Water Alliance (EWA), and EBMUD.
The pilot provides NSJWCD with up to 1,000 acre-feet of EBMUD surface water from the Mokelumne River that participating landowners use for irrigation instead of pumping groundwater from the ESJ Subbasin, thereby storing groundwater for future use. The DREAM groundwater export permit issued by San Joaquin County in 2017 allows EBMUD to draw up to half of the banked groundwater, minus five percent for losses, to use as supplemental supply. The other half will remain in the ESJ Subbasin to help replenish groundwater levels.
In 2018 and 2019, EBMUD released a total of 342 acre-feet of the 1,000 acre-feet of MokelumneRiver water available to NSJWCD as part of the pilot.About one-third of the water released was diverted by NSJWCD and either used for irrigation or accounted for as recharge in the NSJWCD service area.
An existing irrigation well operated by NSJWCD is used to extract the banked groundwater for this project. The additional facilities required to convey groundwater nearly three miles from this well and into EBMUD’s Mokelumne Aqueducts were constructed in 2022. Groundwater extraction took place for approximately two weeks in February 2023 to test the facilities that brought San Joaquin County groundwater into EBMUD’s raw water system for the first time. About 40 acre-feet of groundwater was incorporated with EBMUD’s Mokelumne water supply. After the remainder of the DREAM recharge water is released by EBMUD to NSJWCD in a future year, groundwater extraction will occur for one or two longer periods to complete the pilot test.
Safe and Reliable Future Water
Prior to delivering water to customers throughout the East Bay, EBMUD treats raw water to levels that meet or exceed standards for safe drinking water. When EBMUD blends groundwater into our raw water source as part of the DREAM project, the same high standards of treatment and testing will apply. EBMUD has analyzed the DREAM groundwater source for over 400 constituents over a period of a year. Much like EBMUD’s current drinking water sources, none of these constituents exceeded the maximum contaminant levels set by the EPA.
The results of the DREAM pilot will be used to evaluate the possibility of pursuing a larger groundwater banking project in San Joaquin County with the goal of improving EBMUD’s long-term water supply reliability while also benefitting the ESJ Subbasin.
Grace Su, Associate Civil Engineer
Email: Grace Su