Sweetwater Authority Source of Supply Distribution

Water delivered to Sweetwater Authority consumers is obtained from a variety of sources. In an average year, customers can expect to receive 70 percent of their water from local water supplies including the Sweetwater River, the Sweetwater Alluvium, and the San Diego Groundwater Formation. The remainder, approximately 30 percent, is obtained from imported water sources.

Sweetwater Authority owns and operates Loveland Reservoir, Sweetwater Reservoir, deep freshwater wells, and brackish water wells. The water is treated at the Robert A. Perdue Water Treatment Plant in Spring Valley and the Richard A. Reynolds Groundwater Desalination Facility in Chula Vista. At its National City Wells, the authority obtains freshwater from the San Diego Formation, approximately 800 feet below the surface. These investments have made Sweetwater Authority the only San Diego County water agency that can claim a reliable and diverse water supply.

The Robert A. Perdue Water Treatment Plant and the Richard A. Reynolds Groundwater Desalination Facility use chloramines for secondary disinfection, while the National City Wells use free chlorine. At the contact interface of these different sources, the mixture (i.e., water containing free chlorine and chloramines) can cause a loss in disinfectant residual, which in turn, could potentially lead to nitrification. The use of GIS and water system modeling was instrumental in a project to assess water quality issues, such as nitrification and water age, and determine problem areas and better sampling point locations.