Garrison Dam

Garrison Dam is an earth-fill embankment dam on the Missouri River in central North Dakota. At over two miles (3 km) in length, it is the fifth-largest earthen dam in the world, constructed by the U.S. Army Corps of Engineers from 1947-53. The reservoir impounded by the dam is Lake Sakakawea, which extends to Williston and the confluence with the Yellowstone River, near the Montana border.

Garrison Dam is located between Riverdale and Pick City, 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.

Hydropower turbines at Garrison Dam have an electric power generating nameplate capacity of 583.3 megawatts. Average production of 240 megawatts serves several hundred thousand customers.

The construction on the dam necessitated the purchase of 152,360 acres (616.6 km2) 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 were sold in 1947 for $5,105,625 and ~1700 residents relocated. 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. Earthwork was completed in the fall of 1954 by the Corps of Engineers as part of a flood control and power generation project along the river.

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.

In June 2011, in response to the 2011 Missouri River Floods, the dam was releasing over 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. The first use of the emergency spillway due to flooding started on June 1, 2011 at 8:00am.