|Location||Ventura County, California|
|Primary inflows||Coyote Creek|
|Primary outflows||Coyote Creek|
|Catchment area||100 km2 (39 sq mi)|
|Basin countries||United States|
|Max. length||5.3 km (3.3 mi)|
|Max. width||3 km (1.9 mi)|
|Surface area||1,100 acres (450 ha)|
|Max. depth||240 feet (73 m)|
|Water volume||254,000 acre⋅ft (313,000,000 m3)|
|Shore length1||32.4 miles (52.1 km)|
|Surface elevation||103 m (338 ft)|
|References||U.S. Geological Survey Geographic Names Information System: Lake Casitas|
|1 Shore length is not a well-defined measure.|
Lake Casitas is a man-made lake in 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 June–December 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 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.
- List of dams and reservoirs in California
- List of lakes in California
- List of largest reservoirs of California
- Carlson, Cheri (April 4, 2016). "Drought uncovers family history buried under Lake Casitas". Ventura County Star. Retrieved 5 April 2016.
- Carlson, Cheri (April 18, 2016). "No rain could mean Lake Casitas runs dry in four years". Ventura County Star. Retrieved 22 August 2016.
- Boyd-Barrett, Claudia (September 8, 2014) "Ventura leans on lake for water for eastern half of city" Ventura County Star
- Staff (April 17, 2015). "Lake Casitas just 50 percent full". Ventura County Star.
- Carlson, Cheri (November 10, 2017). "As Lake Casitas shrinks, a search is on for untapped water supplies". Ventura County Star. Retrieved 11 November 2017.
- 1984 Summer Olympics official report. Archived 2010-11-02 at the Wayback Machine. Volume 1. Part 1. pp. 108–12.
- Bureau of Reclamation (February 2010) "Lake Casitas Resource Management Plan/Environmental Impact Statement" United States Department of the Interior
- Bureau of Reclamation (2009). "Ventura River Project". U.S. Department of the Interior. Retrieved 2009-09-29.
- Department of Water Resources (2009). "Station Meta Data: Lake Casitas (CSI)". California Data Exchange Center. State of California. Retrieved 2009-10-11.
- U.S. Geological Survey (13 June 2000). "Feature Detail Report: Main Island". Geographic Names Information System (GNIS). U.S. Department of the Interior. Retrieved 2009-10-12.
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