Clark Canyon Dam is an earthfill

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

located in

Beaverhead County, Montana Beaverhead County is the largest county by area in the U.S. state of Montana. As of the 2020 census, the population was 9,371. Its county seat is Dillon. The county was founded in 1865. Much of the perimeter of the county is the Continental ...

, about 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 The Bureau of Reclamation, formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and operatio ...

, to hold water for downstream irrigation and for

flood control Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...

purposes. Clark Canyon Dam has a crest length of , and a maximum height of . The dam contains 1,970,000 cubic yards (1,510,000 m³) of material. The elevation of the dam crest is . The reservoir has a total capacity of , and when full has a surface area of . Construction of the dam and reservoir required the relocation of U.S. Route 91 (rebuilt as

Interstate 15 Interstate 15 (I-15) is a major Interstate Highway in the Western United States, running through Southern California and the Intermountain West. I-15 begins near the Mexican border in San Diego County and stretches north to Alberta, Ca ...

) and a main line of the

Union Pacific Railroad The Union Pacific Railroad is a Railroad classes, Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United Stat ...

. 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 The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gro ...

camped from August 17 to 22, 1805 and held negotiations with the

Shoshone The Shoshone or Shoshoni ( or ), also known by the endonym Newe, are an Native Americans in the United States, Indigenous people of the United States with four large cultural/linguistic divisions: * Eastern Shoshone: Wyoming * Northern Shoshon ...

Fishing

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

References

External links

Bureau of Reclamation: Clark Canyon Information
Buildings and structures in Beaverhead County, Montana Dams in Montana United States Bureau of Reclamation dams Dams completed in 1964 Earth-filled dams 1964 establishments in Montana {{BeaverheadCountyMT-geo-stub