Montana’s ability to generate electricity for its own uses and for export to neighboring states and provinces is thanks largely to the luck of geography and geology. High elevations along the Continental Divide collect precipitation as snow, which runs off primarily through the Missouri and Clark Fork of the Columbia River systems. Hydroelectric facilities built on Montana streams conservatively deliver close to 2,600 megawatts of electricity (wintertime capacity). Similarly, the massive coal deposits that underlie much of the state contribute another 2,400 megawatts of steam-generated electricity. The renewable energy of wind made an impressive entry into the state’s overall electricity portfolio in recent years and is covered in the history of renewable energy section.
The load profile for the state’s electricity consumption has changed greatly since the early years of mining, smelting, and refining of minerals such as copper. Mineral mining and processing remains a small use for electricity in Montana, while the industrial load centers have shifted or closed operations. Commercial and residential consumption has risen in the post-War decades, both in Montana and in the export markets out of state. More recently, new loads have risen to accommodate the digital, semiconductor, and photovoltaic sectors – data processing centers, for example, and polysilicon and silane gas manufacturing.
Montana's Hydroelectric Portfolio
Thompson Falls Dam, seven-unit, run-of-the-river, 94-megawatt, Clark Fork River. Completed in 1915. Owned by NorthWestern Energy.
Noxon Rapids Dam, 466-megawatt, earthfill and concrete dam on the Clark Fork River. Built by Washing Water Power in 1956 with commissioning in 1959. Owned and operated by Avista, which is currently in negotiation for purchase by the Canadian company Hydro One.
Hebgen Dam, storage, Madison River. A history of the dam is available on the NorthWestern Energy website. Owned by NorthWestern Energy.
Madison Dam, four-unit, run-of-the-river, 9-megawatt, Madison River at head of Bear Trap Canyon. Originally built in 1901 with replacement in 1905-06. Owned by NorthWestern Energy.
Hauser Dam, six-unit, 19-megawatt, run-of-the-river, Missouri River. Completed in 1911 following failure of initial dam in 1908. Owned by NorthWestern Energy.
Holter Dam, four-unit, 48-megawatt, run-of-the-river, Missouri River. Completed in 1918. Owned by NorthWestern Energy.
Black Eagle Dam, three-unit, 21 megawatt, run-of-the-river, Missouri River. Completed in 1891 with new dam and powerhouse rebuild in 1926-27. Owned by NorthWestern Energy.
Rainbow Dam, single-unit, 60-megawatt, run-of-the-river, Missouri River. Completed in 1910 with eight-unit, 35-megawatt capacity; new single-unit powerhouse completed in 2013. Owned by NorthWestern Energy.
Cochrane Dam, two-unit, 64-megawatt, run-of-the-river, Missouri River. Completed in 1958. Owned by NorthWestern Energy.
Morony Dam, two-unit, 48-megawatt, run-of-the-river on the Missouri River. Completed in 1930. Owned by NorthWestern Energy.
Ryan Dam, six-unit, run-of-the-river, 60-megawatt, Missouri River. Completed in 1915 as Volta Dam. Owned by NorthWestern Energy.
Seli's Ksanka Qlispe' Dam (formerly Kerr Dam), three-unit, storage, 194-megawatt, Flathead River at outlet of Flathead Lake. Completed in 1938. Confederated Salish and Kootenai Tribes exercised an option to purchase in 2015.
Mystic Lake Dam, two-unit, 12-megawatt, storage, on Rosebud Creek in Beartooth Mountains. Completed in 1925. Owned by NorthWestern Energy.
Fort Peck Dam, largest earth-fill hydroelectric facility in the U.S., was started in 1933 on the Missouri River with full-pool attained about 1940. Generators were installed in the 1940s and today the facility has three generating units completed in 1951 at 105 megawatts, and two completed in 1961 at 80 megawatts. Generation is divided between the Western Interconnect and the Eastern Interconnect with one generator capable of switching between the two. Owned and operated by the U.S. Army Corps of Engineers.
Milltown Dam, built as Clark Dam in 1908 at the confluence of the Blackfoot and Clark Fork Rivers, run-of-the-river with a capacity of about 3 megawatts. The dam backed up a great deal of metal-laden sediment dating to the flood year of 1908. The dam was decommissioned and removed between 2007 and 2010.
Toston Dam, or Broadwater Dam, on the Missouri River was built in 1940 as a run-of-the-river irrigation facility, but a 10-megawatt turbine was added in 1989. The facility is owned by the state of Montana's Department of Natural Resources & Conservation and is designated a small power production Qualifying Facility by the Federal Energy Regulatory Commission.
Canyon Ferry Dam on the Missouri River originally dates to 1898 with improvements to the generators in 1901. A new dam just downstream was started in 1949 and completed in 1954, which inundated the older facility. The dam's three generators deliver a capacity rated at 50 megawatts. The facility is owned by the Bureau of Reclamation. See also: www.helenahistory.org/dams.htm
Hungry Horse Dam on the South Fork of the Flathead River was completed in 1953 by the Army Corps of Engineers. The dam contributes control to the hydoelectric facility at Kerr Dam downstream on the main Flathead River. Four generators were upgraded in the 1990s to a capacity of 428 megawatts. Owned by U.S. Bureau of Reclamation.
Libby Dam on the Kootenai River was dedicated in 1975 by President Gerald Ford. It was built and is managed by the Army Corps of Engineers and its five turbines generate 600 megawatts, which is marketed and managed by the Bonneville Power Administration.
The Butte Daily Miner, November, 1880
Kirk, Cecil, A History of the Montana Power Company, 2008
Johnson, C., Energy-Power, Copper, and John D. Ryan, Montana the Magazine of Western History, 1988
American Institute of Mining Engineers, meeting program, Butte, 1913
U.S. Patent Office No. 1,194,957, Insulator, April, 1915 and: www.glassian.org/suspension/index.html
Russell, H., Electric Hoists for Mine Service, Mining and Scientific Press, 1913
Jennings, H., Janin, C., The History and Development of Gold Dredging in Montana, Bulletin 121, Bureau of Mines, 1916
Copper: Technology & Competitiveness, Office of Technology Assessment, 1988
Marcosson, I., Anaconda, 1957
Quivik, F., Early Steel Towers and Energy for Montana's Copper Industry, Montana the Magazine of Western History, 1988