Castaic Dam

Castaic Dam is an earth-fill dam located on Castaic Creek and forms Castaic Lake. However, Castaic Creek provides little of its water. The lake is the terminus of the West Branch of the California Aqueduct, also known as the State Water Project. The dam was built by the California Department of Water Resources. The lake has a capacity of 325,000 acre-feet and stores drinking water for the western portion of the Greater Los Angeles Area.

The 18-MW Alamo 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 When demand for electricity is high, usually during the afternoon, water is withdrawn from Pyramid Lake and released into Castaic Lake.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.