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Three Affiliated Tribes
Environmental Division of the Natural Resources Department




The large, man-made Lake Sakakawea occupies 155,000 acres of land in the center of the Reservation. Created by the construction of the Garrison Dam on the Missouri River between 1947 and 1953, the lake stretches 178 miles in length between Williston and Riverdale, North Dakota with a drainage area of 181,400 square miles. The dam created a lake with a surface area at full pool of 368,000 acres encompassed by 1,300 miles of shoreline, six hundred miles of which lie within Reservation boundaries. Only one bridge spans Lake Sakakawea within the Reservation boundaries and it is located west of New Town at the Reservation’s northern edge.

Lake Sakakawea provides municipal source water for the Four Bears, Mandaree, White Shield, Twin Buttes, and Parshall Public Water Systems. The lake is also a major source of recreational opportunities including fishing, boating and water skiing. Industrial use of the lake resource is continuing to increase as energy development on the Reservation increases.

The TAT Environmental Division has partnered with the US Army Corps of Engineers to have additional surface water samples collected at set locations on Lake Sakakawea. These samples are being analyzed for a variety of analytes.