Lake Casitas is a man-made lake in the Los Padres National Forest of Ventura County, California, created by the construction of Casitas Dam on Coyote Creek, two miles (3 km) before it joins the Ventura River. Santa Ana Creek and North Fork Coyote Creek also flow into the lake. The dam was constructed of earth-fill and was completed in 1959. It is 279 ft (85 m) and was built by the United States Bureau of Reclamation. The lake has a capacity of 254,000 acre·ft (313,000,000 m3). The dam was built as part of the Ventura River Project and was strengthened in Jun-Dec 2000 as a seismic improvement to help withstand earthquakes greater than 6.5. The project provides drinking water and water for irrigation. A secondary benefit is flood control. In the center of Lake Casitas is 2 km Main Island, whose peak rises more than 500 feet (150 m) from the lake surface.
Human contact with the water is prohibited by the Board of Directors at the Casitas Municipal Water District. The Board states that since the Lake is used for drinking water body contact with water is not allowed, but fishing, boating, rowing and camping are permitted. During the 1984 Summer Olympics in Los Angeles, Lake Casitas hosted the canoeing and rowing events. The lake was used as the site for filming the scenes of 'Camp Greenlake' in the 19th century. The lake featured in the 2003 film Holes.
The "No Body Contact with Water" Lake Policy was established by The Casitas Municipal Water District in the 1950s and 1960s because the lake did not have a filtration system in place. In the 1990s a multimillion-dollar filtration system upgrade was made to the Lake Casitas facility. The US Department of the Interior conducted a 10-year study on the Lake where allowing body contact with water was explored. The study reported, "The capabilities of the current water filtration system to handle the additional burden of body contact were called into question. The system was shown to exceed current regulatory standards, and would “probably” be sufficient enough to mitigate body contact pollution as well." The Casitas Municipal Water District has not significantly changed the "no body contact with water" regulations in response to the facilities upgrade.