Castaic, Recreation reservoir in Los Angeles County, US

Castaic Lake is a reservoir in Los Angeles County with two water bodies that together cover over 4,500 hectares of parkland with around 47 kilometers of shoreline. The deepest basin reaches down to about 45 meters and sits nestled between gentle hill ranges north of Los Angeles.

Castaic Lake is the terminus of the West Branch California Aqueduct, which carries water from Pyramid Lake through the Angeles Tunnel. The 4,224-acre state recreation area around it was established in 1965. The Elderberry Forebay Dam bisects the lake, creating the adjacent Elderberry Forebay, where the Castaic Power Plant, a pumped-storage hydroelectric facility, uses the aqueduct flow to drive its turbines.

Anglers fish for bass, catfish and occasional rainbow trout while local agencies provide catch recommendations to protect health. Walkers use the shoreline trails for outings with views over the open water and surrounding hills.

Access is via Interstate 5 at exits 176A and 176B in the town of Castaic. Swimming is allowed only on the designated beaches of the lower lagoon, from Memorial Day weekend to Labor Day weekend; swimming is prohibited in the main lake and elsewhere in the lagoon. Since June 30, 2025, the park has been closed on Mondays and Tuesdays because of county budget cuts.

Castaic Lake was a main filming location for Mighty Morphin Power Rangers, used in every season through Power Rangers Wild Force, and also appeared in VR Troopers, Masked Rider and Beetleborgs. The Amazing Race 26 started here on November 12, 2014, and Sabrina Carpenter's 2024 video for "Espresso" was shot at the lake that spring.