Lake Casitas, reservoir in California, USA

Lake Casitas is a large body of water in Ventura County with over 1,100 acres of water surface surrounded by oak trees and hills. The water offers various activities such as fishing, boating, hiking on marked trails, and bird watching, with a marina providing boat rentals and fishing supplies.

The water body was built in 1959 by the U.S. Bureau of Reclamation and has served as a drinking water supply for the local community ever since. It is now managed by the Casitas Municipal Water District and has become an important recreation spot for anglers and nature lovers.

The name Casitas is not traced to nearby hills in the sources; the reservoir takes its name from the Casitas district and dam on Coyote Creek. Visitors today fish, boat, row and camp, but swimming and any body contact with the water are banned because it is a drinking-water supply. The ban dates from the 1950s and 1960s, when the lake had no filtration system.

The lake lies in the Los Padres National Forest about 85 km northwest of Los Angeles, with Oak View and Mira Monte to the east and northeast and Ventura to the southeast. Swimming and any body contact with the water are prohibited because the reservoir supplies drinking water; fishing, boating, rowing and camping are allowed. The recreation area is on the north shore.

In 2003, Andrew Davis filmed "Holes" (Das Geheimnis von Green Lake) at the lake, standing in for the dried-up Green Lake of the story. The reservoir's spillway first ran in 1978 and had operated only eight times as of 2024, so the overflow channel is rarely seen in use.