Pyramid Lake is a reservoir formed by Pyramid Dam on Piru Creek in the eastern San Emigdio Mountains, near Castaic, Southern California. It is a part of the West Branch California Aqueduct, which is a part of the California State Water Project. Its water is fed by the system after being pumped up from the San Joaquin Valley and through the Tehachapi Mountains. History In 1843, gold was discovered near what is now Pyramid Lake, in the Santa Feliciana Canyon, just south of what is now Pyramid Dam. The small find failed to trigger a rush to the mountainous countryside. Only Francisco Lopes, owner of Rancho Temescal, a Mexican land grant, and a handful of ranchers attempted to settle the region. This lake was created in 1972, and completed in 1973, as a holding reservoir for the California State Water Project. The lake was named after a pyramid-shaped rock carved out by engineers building U.S. Route 99. Travelers between Los Angeles and Bakersfield christened the landmark “Pyramid Rock,” which still stands just adjacent to the dam. Geography Pyramid Lake is the deepest lake in the California Water Project system, built up along the steep canyon walls surrounding Piru Creek. The reservoir lies on the border between the Angeles National Forest and the Los Padres National Forest, in the northwestern portion of Los Angeles County. It is to the west of Interstate 5 (I-5) south of Tejon Pass. The former alignment of US 99 is below the waters here, replaced by I-5. Just below the dam, Piru Creek returns to its natural state as it winds down through the Topatopa Mountains to feed into the Lake Piru reservoir and later the Santa Clara River. Water from Pyramid Lake continues through the Angeles Tunnel to Castaic Lake, which is the terminus of the west branch of the aqueduct. Description The earth and rock dam was built by the California Department of Water Resources and was completed in 1973. Pyramid Lake is part of the California Aqueduct, which is part of the California State Water Project. Outflow goes downstream to Castaic Lake, which is the terminus of this West Branch aqueduct line. Pyramid and Castaic lakes act as the upper and lower reservoirs for the Castaic Power Plant, a 1,495 megawatt pumped storage hydroelectric plant located at Castaic Lake. The plant generates electricity from the water that flows down from Pyramid Lake to