Garrison Reservoir

Garrison Reservoir
Name	Garrison Reservoir
Other name	Lake Sakakawea
Caption	Aerial view
Location	McLean County and Mercer County, North Dakota, United States
Coordinates	47°20′N 101°30′W
Type	Reservoir
Inflow	Missouri River
Outflow	Missouri River
Catchment	529,000 km²
Basin countries	United States
Area	307,000 acres
Max-depth	180 ft
Volume	17,000,000 acre-feet
Shore	1,500 miles
Created	1953–1958
Dam	Garrison Dam

Garrison Reservoir

Garrison Reservoir, also known as Lake Sakakawea, is a large reservoir on the Missouri River in central North Dakota, created by the Garrison Dam as part of the Pick–Sloan Missouri Basin Program. The reservoir inundated portions of the Fort Berthold Indian Reservation and reshaped regional transportation infrastructure, energy production, and agricultural irrigation. It is a focal point for federal water management, Native American land rights, and Great Plains environmental change.

History

The reservoir resulted from mid-20th century federal initiatives following the Great Depression and World War II, including the Flood Control Act of 1944, the Pick–Sloan Plan, and policies developed by the United States Army Corps of Engineers, the Bureau of Reclamation, and the Tennessee Valley Authority as models for basin-scale projects. Construction of Garrison Dam (1953–1958) paralleled projects like Hoover Dam and Grand Coulee Dam and led to displacement of communities such as Sanish, North Dakota, Elbowoods, North Dakota, and portions of New Town, North Dakota. The inundation profoundly affected the Three Affiliated Tribes (Mandan, Hidatsa, and Arikara Nation) and intersected with legal actions involving the Indian Claims Commission and later cases before the United States Court of Claims and the Eighth Circuit Court of Appeals.

Geography and Hydrology

The impoundment forms the largest reservoir in North Dakota and one of the largest in the United States by surface area, extending across Mountrail County, Mercer County, and McLean County. It alters the Missouri River corridor between Williston, North Dakota and Bismarck, North Dakota, connecting to tributaries such as the Knife River and Heart River via altered floodplains. Hydrologic regulation is coordinated among the U.S. Army Corps of Engineers, Bureau of Reclamation, and North Dakota State Water Commission and integrates with systems including the Fort Peck Lake and Oahe Lake reservoirs. Seasonal drawdowns, managed releases for downstream municipalities like Bismarck and Fargo, North Dakota, and power generation influence stratification, evaporation rates, and sediment deposition patterns similar to those observed at Lake Powell and Lake Mead.

Construction and Engineering

Engineering of the dam and reservoir employed techniques comparable to major 20th-century projects such as Boulder Dam and Glen Canyon Dam. Contractors coordinated with firms experienced on Tennessee Valley Authority projects and engaged heavy equipment like draglines and cofferdams. The design incorporated a concrete gravity section and earthfill embankments, with spillways and hydroelectric turbines installed to provide capacity similar in scale to regional plants operated by utilities such as Great River Energy and Basin Electric Power Cooperative. Construction required relocation of rail lines of companies like Northern Pacific Railway and highway realignments related to U.S. Route 2 and Interstate 94 corridors. Archaeological mitigation involved scholars from institutions including Smithsonian Institution and University of North Dakota due to inundation of prehistoric Mandan, Hidatsa, and Arikara sites.

Ecology and Environmental Impact

Creation of the reservoir transformed prairie and riverine ecosystems, converting riparian corridors into lacustrine habitat and affecting species documented by agencies such as the U.S. Fish and Wildlife Service and the North Dakota Game and Fish Department. Fish communities shifted toward warmwater assemblages with prominent populations of walleye, northern pike, and white bass, influencing mercury dynamics studied by the Environmental Protection Agency. Wetland loss affected migratory birds along the Central Flyway, impacting nesting sites for piping plover and waterfowl monitored by Audubon Society researchers. Invasive species concerns mirror those at Erie Canal and Lake Winnipeg, with management efforts coordinated through programs involving the U.S. Coast Guard Auxiliary and regional conservation districts. Long-term impacts include shoreline erosion, changed groundwater recharge, and altered sediment transport documented in studies by the United States Geological Survey and university research centers like North Dakota State University.

Recreation and Economic Uses

The reservoir supports recreation and commercial activities similar to those at other federal reservoirs, with parks managed by the North Dakota Parks and Recreation Department and campsites near Knife River Indian Villages National Historic Site. Boating, angling, and hunting attract visitors from Minneapolis, Fargo, North Dakota, and Bismarck, supporting local economies in towns like Williston and New Town. Hydrocarbon development on nearby uplands involves companies such as Bakken Formation operators, and reservoir water facilitates irrigation projects that connect to agricultural producers represented by groups like the National Farmers Union. Tourism interfaces with Indigenous cultural tourism promoted by the Mandan, Hidatsa, and Arikara Nation and events hosted in venues comparable to county fairs in Mercer County, North Dakota.

Management and Controversies

Management involves federal, state, and tribal entities including the U.S. Army Corps of Engineers, the Mandan, Hidatsa, and Arikara Nation Tribal Council, and state agencies, leading to controversies over compensation, land rights, and environmental mitigation similar to disputes at Kinzua Dam and Glen Canyon. Litigation over losses pursued remedies through the Indian Claims Commission and subsequent federal settlements, while advocacy groups including Natural Resources Defense Council and tribal organizations pressed for cultural resource protection. Contemporary debates focus on water allocation during droughts, balancing hydroelectric generation for utilities like Western Area Power Administration with cultural site preservation and fisheries management, echoing conflicts seen in interbasin transfers like the Central Arizona Project.

Category:Reservoirs in North Dakota Category:Lakes of the Missouri River