[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.

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.

[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.

[10][2] 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.