Project Concept
The pilot project uses in-lieu groundwater banking to store groundwater in the ESJ Subbasin. EBMUD provides NSJWCD with up to 1,000 acre-feet of EBMUD surface water from the Mokelumne River. Participating landowners can use the EBMUD surface water supply for irrigation instead (in-lieu) of pumping groundwater from the ESJ Subbasin, thereby allowing groundwater to be banked for future use. Under the DREAM groundwater export permit issued by San Joaquin County in 2017, EBMUD can 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 the region.
Recharge Operations
In 2018 and 2019, EBMUD released a total of 342 acre-feet of the 1,000 acre-feet of Mokelumne River water available to NSJWCD as part of the pilot project. 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.
In 2023, EBMUD released an additional 592 acre-feet of Mokelumne River water as part of the pilot project. About 231 acre-ft was diverted for irrigation, and the remaining recharged into the basin and a portion lost to evapotranspiration.
Extraction Operations
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.
Additional groundwater extraction is scheduled for January through March 2024 to extract approximately 296 acre-feet, or the remainder of the DREAM recharge water banked in 2023. The 2024 extraction period will 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. For the DREAM Project, EBMUD blends groundwater into our raw water source and maintains the same high standards of treatment and testing. EBMUD has analyzed the DREAM Project groundwater source for over 400 constituents over a period of one year. Much like EBMUD’s current drinking water sources, these constituents are less than the maximum contaminant levels set by the EPA.
The DREAM pilot project 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 Subbasinin.
Contact Information
Grace Su, Senior Civil Engineer
Email: Grace Su
Phone: 510-287-7013
Other Sources of Information
Additional details about the DREAM Project can be found on San Joaquin County’s DREAM webpage and NSJWCD’s website.