Oahe Dam

Oahe Dam
Oahe powerhouse showing surge chambers and part of powerhouse, looking to north-west.
Official name	Oahe Dam
Location	44°27′07″N 100°23′57″W / 44.45194°N 100.39917°W / 44.45194; -100.39917 Hughes / Stanley counties, South Dakota, USA
Construction began	1948
Opening date	1962
Construction cost	$340 Million
Dam and spillways
Height	245 feet (75 m)
Length	9,360 feet (2,850 m)
Volume	93,122,000 cubic yards (71,197,000 m3)
Impounds	Missouri River
Spillways	8
Reservoir
Creates	Lake Oahe
Capacity	23,500,000 acre feet (29.0 km3)
Surface area	206,100 acres (83,400 ha)
Power station
Turbines	7
Installed capacity	786 MW

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.

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.

History

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.

Statistics

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

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 (610 square kilometres) bringing it down to 2,850,000 acres (11,534 km²) today. Standing Rock Reservation lost 55,993 acres (227 km²) leaving it with 2,300,000 acres (9,308 km²). 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.^[1] 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.^[2]

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.

2011 Flooding

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).^[3] The previous release record was 53,900 cu ft/s (1,526 m³/s) in 1997.

See also

• Garrison Dam
• List of reservoirs and dams in the United States

References

• 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

External links

• Oahe Dam and Lake Oahe, A Sightseer's Guide to Engineering page
• Boat ramp conditions
• Oahe Project Homepage – U.S. Army Corps of Engineers

Coordinates: 44°27′04″N 100°24′08″W / 44.45111°N 100.40222°W / 44.45111; -100.40222

v t e Dams on the Missouri River Toston Dam · Canyon Ferry Dam · Hauser Dam · Holter Dam · Black Eagle Dam · Rainbow Dam · Cochrane Dam · Ryan Dam · Morony Dam · Fort Peck Dam · Garrison Dam · Oahe Dam · Big Bend Dam · Fort Randall Dam · Gavins Point Dam