This report estimates the water supply‑related peak electrical demands for investor‑owned electric utilities in California, based on data from the California Energy Commission and California investor‑owned utilities. Water supply‑related electrical demands exceed 2,000 megawatts on summer peak days in California. Agricultural groundwater and surface water pumping represent 60 percent of the total water supply‑related peak day electrical demand, with water agency demands representing the remaining 40 percent. Over 500 megawatts of water agency electrical demand is used for providing water/sewer services to residential water customers. This study also forecasts future peak‑day electrical loads and estimates peak demand impacts of population growth and the impact of potential demand reduction programs.