|Location||Custer County, Oklahoma|
|Primary inflows||Washita River|
|Primary outflows||Washita River|
|Catchment area||1,496 square miles (3,870 km2)|
|Basin countries||United States|
|Managing agency||U.S. Bureau of Reclamation|
|First flooded||October 1962|
|Max. length||10.91 miles (17.56 km)|
|Max. width||2 miles (3.2 km)|
|Surface area||8,800 acres (3,600 ha)|
|Water volume||256,220 acre⋅ft (316,040,000 m3)|
|Shore length1||63 mi (101 km)|
|Surface elevation||1,652 feet (504 m)|
|Settlements||Foss, Oklahoma; Clinton, Oklahoma|
|1 Shore length is not a well-defined measure.|
Foss Reservoir, also known as Foss Lake, is in Custer County, Oklahoma on the Washita River, about 15 miles (24 km) west of Clinton, Oklahoma. The reservoir was constructed during 1958–1961 by the U. S. Bureau of Reclamation. The project was known originally as the Washita Basin Project. The lake and dam were named for the community of Foss, Oklahoma, about 6 miles (9.7 km) south of the site. The primary purposes are to regulate flow of the river and to provide water for the cities of Bessie, Clinton, Cordell and Hobart. It is western Oklahoma's largest lake and lies entirely within Foss State Park.
The reservoir has a surface area of 8,800 acres (3,600 ha) and a shoreline of 63 miles (101 km). The capacity of the reservoir is 436,812 acre feet (538,800,000 m3). The reservoir serves a catchment area of 1,496 square miles (3,870 km2). The reservoir has a mean depth of 23 feet (7.0 m) and a maximum depth of 89 feet (27 m).
Dam construction began in October, 1958. The dam is 142 feet (43 m) high, 38 feet (12 m) wide (at the crest) and 18,130 feet (5,530 m) long.
Foss State Park
Foss State Park encompasses 1,749 acres (7,080,000 m2) of land and contains 8 campgrounds, swimming beach, 6 boat ramps, a playground, marina, and a restaurant. It also has 19 miles (31 km) of equestrian and multi-use trails. Foss State Park is often mentioned as a target for sale or closure to help close the state's current budget deficit. Already the state has sold a herd of bison as "surplus property." The bison had recently been moved into Foss State Park from another location in western Oklahoma.
The water quality in Lake Foss is extremely hard. The Bureau of Reclamation built one of the first electrodialysis plants in the United States to process the water before it is delivered to users. The Oklahoma Department of Environmental Quality constructed a new, updated plant to replace the original in 2002. The new plant, built by Ionics, Inc., would also increase production of potable water for its municipal customers from 3 million to 4.5 million U.S. gallons per day.
Water is transported from the dam to consumers via three pumping stations and 50.8 miles (81.8 km) of aqueducts.
Cold cases involving cars found in the lake
In September 2013, two cars believed to have been submerged since 1969, and 1970 were found at the bottom of Foss Reservoir by Oklahoma Highway Patrol officers testing new sonar equipment. The cars, a 1952 Chevrolet and a blue 1969 Chevrolet Camaro, each contained three sets of skeletal human remains. They were suspected to be linked to two separate, long-open cold cases from the late 1960s, in the case of the older car, and 1970, in the case of the Camaro. In October 2014, it was announced that both cases were solved, with the 1969 case involving three adults and the 1970 case involving three teenagers. Both cases were ruled accidental.
- "Foss Reservoir 5-year Fisheries Management Plan." Undated. Accessed July 17, 2018.
- U. S. Department of the Interior. "Washita Basin Project." Updated April 5, 2013. Retrieved July 1, 2013.
- "Foss Lake, Oklahoma." Retrieved July 2, 2013.
- "Leisure and Sports Review (LASR):Foss Lake, OK." Retrieved July 2, 2013.
- ScoopWeb. "Foss Dam News." Retrieved July 2, 2013
- "Herd of bison from Foss State Park up for auction on state’s surplus website." KOCO 5 News. May 9, 2018. (Video) Accessed July 18, 2018.
- Wayne Boothe, "Foss." Encyclopedia of Oklahoma History and Culture. Retrieved July 2, 2013.
- "Oklahoma reservoir expands water desalination facility with Ionics." Water & Wastes Digest. November 6, 2002. Accessed July 17, 2018.
- "Bureau of Reclamation. "Washita Basin Project." Retrieved July 3, 2013". Archived from the original on March 3, 2016. Retrieved July 3, 2013.
- Cold, wet cases: Oklahoma troopers stumble on six bodies in two cars at bottom of lake - Retrieved September 18, 2013
- Fantz, Ashley (23 October 2014). "Oklahoma cases solved: DNA tests show Foss Lake remains are 6 missing people". CNN. Retrieved 23 October 2014.