In the early 1990’s, one of the Water Authority’s earliest efforts to diversify the region’s water supply portfolio focused on groundwater development. To this day, the Water Authority provides financial and technical assistance to its member agencies to help in the further development and use of the region’s groundwater aquifers, with the goal of increasing supply to equal 6 percent of total normal-year water demand by 2011.


Production of groundwater as a water supply to the San Diego region requires the extraction of water from underground reservoirs, known as aquifers. Groundwater in the San Diego region is mostly found as saline brackish water. Brackish water requires an additional desalination treatment process. Groundwater production in the Water Authority’s service area is limited by a number of elements, including lack of storage capacity in local aquifers, availability of groundwater recharge, and degraded water quality. Narrow river valleys filled with shallow sand and gravel deposits are characteristic of the most productive groundwater basins in the San Diego region. Outside of the principal alluvial aquifers and farther inland, groundwater occurs in fractured crystalline bedrock and semi-consolidated sedimentary deposits where yield and storage are limited and the aquifers are best suited for lower-yielding domestic water supply wells.

Alluvial Groundwater Basins

Although groundwater supplies are less plentiful in the San Diego region than in some other areas of California, the Water Authority is exploring undeveloped supplies that may exist. These supplies could help meet a greater portion of the region’s future water supply and storage needs. Several agencies within the Water Authority’s service area have documented potential projects that could provide an additional 22,000 acre-feet of groundwater production in fiscal year 2015.

icon_pdf.png Groundwater Demand Projections