Garrison Dam
Aerial view of Garrison Dam, impounding Lake Sakakawea on the Missouri River
Location of Garrison Dam in North Dakota
Country	United States
Location	McLean/Mercer Counties, North Dakota
Coordinates	47°29′55″N 101°24′43″W / 47.49861°N 101.41194°W / 47.49861; -101.41194
Status	Operational
Construction began	1947; 77 years ago (1947)
Opening date	1953; 71 years ago (1953)
Construction cost	US $300 million
Owner(s)	U.S. Army Corps of Engineers, Omaha District
Dam and spillways
Type of dam	Embankment, rolled earth-fill
Impounds	Missouri River
Height	210 ft (64 m)
Length	11,300 ft (3,444 m)
Elevation at crest	1,854 feet msl
Width (crest)	60 ft (18 m)
Width (base)	0.5 mi (1 km)
Dam volume	66,500,000 cu yd (50,842,898 m3)[1]
Spillway type	Service, 28 controlled-gates
Spillway capacity	660,000 cu ft/s (18,689 m3/s)[2]
Reservoir
Creates	Lake Sakakawea
Total capacity	23,821,000 acre⋅ft (29.383 km3)[2]
Catchment area	123,900 m2 (1,334,000 sq ft)
Surface area	382,000 acres (1,546 km2)
Maximum length	178 mi (286 km)
Maximum water depth	180 ft (55 m)
Normal elevation	1,854 ft (565 m) (max)
Power Station
Operator(s)	U.S. Army Corps of Engineers
Commission date	January 1956–October 1960[2]
Turbines	3 x 121.6 MW, 2 x 109.25 Francis type
Installed capacity	583.3 MW[3]
Annual generation	2,250 GWh (1967-2009 Average)[2]
Website www.nwo.usace.army.mil/Missions/Dam-and-Lake-Projects/Missouri-River-Dams/Garrison

Garrison Dam is an earth-fill embankment dam on the Missouri River in central North Dakota, U.S. Constructed by the U.S. Army Corps of Engineers from 1947 to 1953, at over 2 miles (3.2 km) in length, the dam is the fifth-largest earthen dam in the world.^[4] The reservoir impounded by the dam is Lake Sakakawea, which extends to Williston and the confluence with the Yellowstone River, near the Montana border.

Location

Garrison Dam is located between Riverdale and Pick City, and named after the town of Garrison, directly north of the dam, across the reservoir. The dam is approximately midway between Bismarck and Minot, about 10 miles (16 km) west of U.S. Highway 83.

History

The dam was part of a flood control and hydroelectric power generation project named the Pick-Sloan Project along the river, after the two plan developers, Col. Lewis A. Pick and William Glenn Sloan. Local communities in the area had resisted having the dam built at other locations on the river where they would be affected.

In order to construct the dam, the US government needed to purchase 152,360 acres (616.6 km²) of bottomlands in the Fort Berthold Reservation that would be flooded by the creation of Lake Sakakawea. These lands were owned by the Three Affiliated Tribes, and the territory "had been their home for perhaps more than a millennium".^[5]: 234

Threatened by confiscation under eminent domain, the tribes protested. A complete block of Garrison Dam power was denied because it would violate the 1935 Rural Electrification Act. The tribes gained remuneration, but lost 94% of their agricultural land^{[6]: 59–60} in 1947, when they were forced to accept $5,105,625. This amount was increased to $7.5 million in 1949, but it did not fully compensate them for the loss of their important farmlands, homes, towns, and graves. They had cultivated the bottomlands and were able to be largely self-sufficient.^[6]: 61

The final settlement legislation denied the tribes' right to use the reservoir shoreline for traditional grazing, hunting, fishing or other purposes, including irrigation development and royalty rights on all subsurface minerals within the reservoir area.^[6]: 61 About 1,700 residents were forcibly relocated, some to New Town, North Dakota at the northern end of the reservation.^[7]

Thus construction of Garrison Dam almost totally destroyed the traditional way of life for the Three Affiliated Tribes and made them much more dependent on the federal government. In addition, the size the lake, and the lack of bridges to cross it for decades, disrupted traditional relations among the peoples. It created new divisions among the segments on the reservation^[6]: p27 Construction on the $300-million dam project began in 1947, and its embankment was enclosed in April 1953. The dam was dedicated by President Eisenhower two months later. The Corps of Engineers completed earthwork in the fall of 1954.^[3]

Garrison Dam is one of six Missouri River Main stem dams operated by the U.S. Army Corps of Engineers, Omaha District. The dam upstream of Garrison Dam is Fort Peck Dam (near Fort Peck, Montana). The dams downstream of Garrison Dam are: Oahe Dam (near Pierre, South Dakota), Big Bend Dam (near Fort Thompson, South Dakota), Fort Randall Dam (near Pickstown, South Dakota), and Gavins Point Dam (near Yankton, South Dakota). These six mainstem dams impound these Missouri River reservoirs with a total combined water storage capacity of approximately 73,129,000 acre⋅ft (90.203 km³) and approximately 1,111,884 acres (449,963 ha) of water surface area.

In June 2011, in response to the 2011 Missouri River Floods, the dam was releasing more than 140,000 cubic feet per second (4,000 m³/s), which greatly exceeded its previous record release of 65,000 cu ft/s (1,800 m³/s) set in 1997.^[8] The first use of the emergency spillway due to flooding started on June 1, 2011, at 8:00am.^[9]

Energy generation

Hydropower turbines at Garrison Dam have an electric power generating nameplate capacity of 583.3 MW.^[2] Average production of 257 MW serves several hundred thousand customers.^[10][2]

Fishing

The Garrison Dam National Fish Hatchery is the world's largest walleye and northern pike producing facility and also works to restore endangered species, such as the pallid sturgeon.^[11]