Oahe powerhouse showing surge chambers and part of powerhouse, looking to north-west.
|Official name||Oahe Dam|
|Location||Hughes / Stanley counties, South Dakota, USA|
|Construction cost||$340 Million|
|Operator(s)||United States Army Corps of Engineers|
|Dam and spillways|
|Height||245 feet (75 m)|
|Length||9,360 feet (2,850 m)|
|Dam volume||93,122,000 cubic yards (71,197,000 m3)|
|Total capacity||23,137,000 acre feet (28.539 km3)|
|Surface area||374,000 acres (151,000 ha) (max)|
|Commission date||April 1962–June 1963|
|Turbines||7x 112.29 MW|
|Installed capacity||786 MW|
|Annual generation||2,621 GWh|
The Oahe Dam is a large dam along the Missouri River, just north of Pierre, South Dakota in the United States. It creates Lake Oahe, the fourth largest artificial reservoir in the United States, which stretches 231 miles (372 km) up the course of the Missouri to Bismarck, North Dakota. The dam's powerplant provides electricity for much of the north-central United States. It is named for the Oahe Indian Mission established among the Lakota Sioux in 1874. The project provides flood control, electric power, irrigation, and navigation benefits, estimated by the Corps of Engineers at $150,000,000 per year.
In September and October 1804, the Lewis and Clark Expedition passed through what is now Lake Oahe while exploring the Missouri River.
Oahe Dam was authorized by the Flood Control Act of 1944, and construction by the United States Army Corps of Engineers began in 1948. The earth main dam reached its full height in October, 1959. It was officially dedicated by President John F. Kennedy on August 17, 1962, the year in which it began generating power. The original project cost was $340,000,000.
- Dam height: 245 feet (75 m)
- Dam volume of earth fill: 92,000,000 cubic yards (70,000,000 m³)
- Dam volume of concrete: 1,122,000 cubic yards (858,000 m³)
- Spillway width: 456 feet (139 m)
- Spillway crest elevation: 1,596.5 feet (486.6 m)
- Lake maximum depth: 205 feet (62 m)
- Plant discharge 56,000 cubic feet per second (1,600 m3/s)
- Water speed through intake tunnels: 11 mph (5 m/s)
- Intake tunnel length: 3,650 feet (average) (1110 m)
- Number of turbines: 7, Francis type, 100 RPM
- Power generated per turbine: 112.29 MW
- reservoir storage capacity: 23,500,000 acre feet (29.0 km3).
- States served with electricity: North Dakota, South Dakota, Nebraska, Minnesota and Montana
- Number of recreation areas around lake: 51
- Shore length: 2,250 miles (3,620 km)
- Counties bordering lake: 14, including 4 in North Dakota (Burleigh, Emmons, Morton, Sioux), and 10 in South Dakota (Campbell, Corson, Dewey, Haakon, Hughes, Potter, Stanley, Sully, Walworth, and Ziebach)
Tours of the powerplant are given daily Memorial Day through Labor Day.
Native American displacement
As a result of the dam's construction the Cheyenne River Indian Reservation lost 150,000 acres (61,000 hectares) bringing it down to 2,850,000 acres (1,150,000 ha) today. Standing Rock Reservation lost 55,993 acres (22,660 ha) leaving it with 2,300,000 acres (930,000 ha). Much of the land was taken by eminent domain claims made by the Bureau of Reclamation. Over and above the land loss, most of the reservations' prime agricultural land was included in the loss. The loss of this land had a dramatic effect on the Indians who lived on the reservations. Most of the land was unable to be harvested (to allow the trees to be cut down for wood, etc.) before the land was flooded over with water. One visitor to the reservations later asked why there were so few older Indians on the reservations, and was told that "the old people had died of heartache" after the construction of the dam and the loss of the reservations' land.
Excessive precipitation in the spring, along with melting snow from the Rocky Mountains forced the dam to open the release gates (not the spillway), releasing 110,000 cu ft/s (3,115 m3/s) in June with another 50,000 cu ft/s (1,416 m3/s) through the power plant totaling 160,000 cu ft/s (4,531 m3/s). The previous release record was 53,900 cu ft/s (1,526 m3/s) in 1997.
- "Summary of Engineering Data – Missouri River Main Stem System" (PDF). Missouri River Division. U.S. Army Corps of Engineers. August 2010. Retrieved 2012-08-17.
- Carrels, Peter (1999). Uphill Against Water. University of Nebraska Press. ISBN 0-8032-6397-X.
- "The Indians Are Getting Uppity". Ilze Choi. dickshovel.com. Retrieved April 5, 2009.
- Associated Press (June 7, 2011). "Oahe Dam Releases Water With Rumbling Force". Retrieved June 7, 2011.
- Lawson, Michael L. Dammed Indians: the Pick-Sloan Plan and the Missouri River Sioux, 1944–1980. Norman: University of Oklahoma Press, 1982. ISBN 0-8061-2672-8
- Lazarus, Edward. Black Hills, White Justice: The Sioux Nation Versus the United States, 1775 to the Present. New York: Harper Collins, 1991. ISBN 0-06-016557-X.
- Cornell University site
- U.S. Army Corps of Engineers pamphlet "Oahe Power Plant", no date
- Summary of Engineering Data – Missouri River Main Stem System http://www.nwd-mr.usace.army.mil/rcc/projdata/summaryengdat.pdf
- Oahe Dam and Lake Oahe, A Sightseer's Guide to Engineering page
- Boat ramp conditions
- Oahe Project Homepage – U.S. Army Corps of Engineers