Castaic Dam

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Castaic Dam is a dam located on Castaic Creek and forms Castaic Lake. It is an earth-fill dam, though its surfaces are covered with boulders and cobble-sized rocks to prevent erosion. It is near the city of Castaic, California. However, Castaic Creek provides little of its water. The lake is the terminus of the West Branch of the California Aqueduct, part of the State Water Project. The dam was built by the California Department of Water Resources and construction was completed in 1973. The lake has a capacity of 325,000 acre-feet (401,000,000 m³) and stores drinking water for the western portion of the Greater Los Angeles Area.

The 11 MW Foothill Feeder hydroelectric power plant is located at the base of the dam and generates electricity when water is needed in Los Angeles. The 1,495 MW Castaic pumped-storage hydroelectric power plant is located other end of the lake. Castaic Lake serves as the lower reservoir, while Pyramid Lake serves as the upper. When demand for electricity is high, usually during the afternoon, water is withdrawn from Pyramid Lake and released into Castaic Lake. At night, when demand is low, water is pumped back into Pyramid Lake. The sale of peak electricity reduces the Department of Water Resources' overall electric costs for operating the California Aqueduct.