AWWA REUSE52084

The Dublin San Ramon Services District (DSRSD) of Dublin, California, and the East Bay Municipal Utility District (EBMUD) of Oakland, California, formed a Joint Powers Authority known as the DSRSD-EBMUD Recycled Water Authority (DERWA). The purpose of DERWA is to implement water recycling projects in the San Ramon Valley in California. An Environmental Impact Report for the San Ramon Valley Recycled Water Program identified a potential adverse impact on the Alameda County Water District (ACWD)due to a likely increase in salt in the downstream ACWD water supply. A Salt Mitigation Study was undertaken to quantify the impacts of future water recycling irrigation practices on ACWD's downstream water supply. The concentration of salt in the water supply would likely increase because most of the recycled water project area lies within ACWD's watershed, and the recycled water has higher salt concentrations than the potable water it replaces. Specifically, the Study was designed to estimate the fraction of applied salts in recycled water that will migrate into the downstream water supply. Furthermore, an estimate of the lag time at which the impacts may occur was made as part of the Study. This paper describes the study and summarizes preliminary findings. Includes 5 references.