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.

Clark Canyon Dam has a crest length of 2,950 feet (900 m), and a maximum height of 147 feet (45 m). The dam contains 1,970,000 cubic yards (1,510,000 m³) of material. The elevation of the dam crest is 5,578 feet (1,700 m). The reservoir has a total capacity of 325,324 acre-feet (401,281,000 m), and when full has a surface area of 5,903 acres (23.89 km).

Construction of the dam and reservoir required the relocation of U.S. Route 91 (rebuilt as Interstate 15) and a main line of the Union Pacific Railroad. The reservoir inundated the former site of the small community of Armstead, Montana, and the site of Camp Fortunate, where the Lewis and Clark Expedition camped from August 17 to 22, 1805 and held negotiations with the Shoshone.

Fishing is a popular activity on the reservoir created by the dam. The reservoir is regularly stocked with fish.

Fish species within the lake

Species	Family	Class	Native to MT
Brook Trout	Trout	Coldwater	Introduced
Brown Trout	Trout	Coldwater	Introduced
Burbot	Codfish	Coldwater	Native
Common Carp	Minnow	Warmwater	Introduced
Longnose Sucker	Sucker	Warmwater	Native
Mountain Whitefish	Trout	Coldwater	Native
Rainbow Trout	Trout	Coldwater	Introduced
White Sucker	Sucker	Warmwater	Native

• Bureau of Reclamation: Clark Canyon Information