Clark Canyon Dam is an earthfill dam located in Beaverhead County, Montana, about 20 miles (32 km) south of the county seat of Dillon. The dam impounds the waters of the Beaverhead River, creating a body of water known as Clark Canyon Reservoir. The structure was constructed in 1961-1964 by the United States Bureau of Reclamation, to hold water for downstream irrigation and for flood control purposes.