MCWD's desalination treatment plant supplements and diversifies MCWD's water supply sources. The plant was constructed in 1996 and placed in operation in January 1997. At full capacity it can produce 300,000 gallons per day of potable water.
In 1997-1998, MCWD completed a one-year study comparing water quality of the ocean water and intake well groundwater, seasonal groundwater flow and time of travel for microbial contaminants. The California Department of Public Health evaluated the results and concluded the desalination plant seawater intake well located at Marina State Beach is groundwater not under the direct influence of surface water.
With the recent rise in energy costs and the fact that the additional water supply is currently not needed, the desalination plant is not being operated. However, MCWD maintains state and federal water quality monitoring requirements for the seawater intake well.