Oahe Dam

Upper Lake Oahe (Reservoir), between Cannon Ball, North Dakota, and Pollock, South Dakota, as seen from space, October 1985. South is at the top of the photo.

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 world's first rock tunnel boring machine (TBM) was invented in 1952 by James S. Robbins for the Oahe Dam project,[2] which marked the beginning of machines replacing human tunnelers.[3] 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.

The lower Oahe Reservoir and Oahe Dam are near the bottom of this view; Lake Sharpe and Big Bend Dam are near the top, as seen from space, August, 1989. Pierre, South Dakota is near the bottom of the photo; Chamberlain, South Dakota is near the top. South-east is at the top.

• 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.

Oahe Dam from the International Space Station

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 regions where the populations were resettled had soil with a higher clay content, and resources such as medicinal plants were less prevalent.[4]

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.[5] 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.[6] As of 2015, poverty remains a problem for the displaced populations in the Dakotas, who are still seeking compensation for the loss of the towns submerged under Lake Oahe, and the loss of their traditional ways of life.[7]

Huff Archeological Site is a fortified Mandan village site on what is now the bank of Lake Oahe. It is designated a National Historic Landmark, but is endangered by erosion pressure from the lake.

Oahe Dam release gates discharging floodwater at a record 160,000 cubic feet/second in June, 2011.

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).[8] The previous release record was 53,900 cu ft/s (1,526 m³/s) in 1997.

• Keystone Pipeline
• List of reservoirs and dams in the United States

• 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

• U.S. Army Corps of Engineers - Oahe Project
• Daily Reservoir Water Levels and Water Releases Information (U.S. Army Corps of Engineers)