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Dams and Reservoirs on the Upper Missouri River
Two dams have greatly affected the Missouri River in North Dakota since the expedition of Lewis and Clark. Those dams are Garrison Dam between Pick City and Riverdale, North Dakota, and Oahe Dam near Pierre, South Dakota.
The Missouri River drains one–sixth of the United States and flows 2,341 miles from its headwaters at the confluence of the Gallatin, Madison, and Jefferson Rivers at Three Forks, Montana, to its confluence with the Mississippi River at St. Louis, Missouri (U.S. Geological Survey, 2001).
One–third of the Missouri River has been transformed into lake environments, due to six dams built in Montana, North Dakota, South Dakota, and Nebraska (U.S. Geological Survey, 2001). Four of these dams, Fort Peck in Montana, Garrison in North Dakota, and Oahe and Fort Randall in South Dakota, are among the world’s largest dams in terms of volume (The Learning Network, Inc.). The remaining dams are Big Bend in South Dakota and Gavins Point on the South Dakota–Nebraska border.
Missouri River Flow
The flow of the Missouri River and the ecosystems along it have changed drastically since the time of Lewis and Clark. According to the U.S. Geological Survey’s Missouri River Story (2001):
These changes have significantly altered the Missouri River ecosystem. In the upper river, a new ecosystem has been created with the deep water reservoirs replacing the free–flowing river and inter–reservoir reaches affected by lower water temperatures and reduced sediment loads. In the lower river, channelization has eliminated sandbars, depth diversity, and river connections with off–channel side channels and backwaters. The historical flow regime has been transformed with spring high flows now captured in reservoirs and low summer and fall flows augmented with reservoir releases.
All of these changes have lowered populations for many river fish and bird species, some to the extent that they are federal or state–listed as endangered, threatened, or species of special concern.
The flow of the river is managed by the U.S. Army Corps of Engineers.
Garrison Dam is the fifth largest earthen dam in the United States (North Dakota Tourism Department; U.S. Army Corps of Engineers, 2000) and created Lake Sakakawea, the third–largest man–made reservoir in the United States (North Dakota Tourism Department; U.S. Army Corps of Engineers, 2000). The dam is maintained for the production of hydroelectric power, flood control, recreation, fish and wildlife, water supply, irrigation, and regulation of downstream flows for navigation (North Dakota Tourism Department; U.S. Army Corps of Engineers, 2000).
Oahe Dam created Lake Oahe, the fourth–largest man–made reservoir in the United States (U.S. Army Corps of Engineers, 2000). Lake Oahe spans both North and South Dakota. The dam is maintained for the production of hydroelectric power, flood control, regulation of downstream flows for navigation, recreation, fish and wildlife, water supply and irrigation (U.S. Army Corps of Engineers, 2000).
For more information about Lewis and Clark in South Dakota, see: http://www.state.sd.us/gfp/sdparks/lewis/adventur.htm.
Elevation, Contents, Water–Discharge, and Water–Quality Records
To view elevation, contents*, water–discharge** and water–quality records for USGS gaging stations on the Missouri River, Lake Sakakawea, and Lake Oahe, click on the links below.
Data for other gaging stations on Lake Oahe are available at http://sd.water.usgs.gov.
*Contents is the volume of water in a reservoir or lake. Unless otherwise indicated, volume is computed on the basis of a level pool and does not include bank storage.
**Water discharge is the volume of water that passes a given point in a given period of time. Usually measured in cubic feet per second, ft3/s.
North Dakota Tourism Department, n.d., Garrison Dam: accessed June 21, 2001, at URL http://www.ndlewisandclark.com/sites/garrison.html.
The Learning Network Inc, n.d., World’s Largest Dams: accessed June 25, 2001, at URL http://ln.infoplease.com/ipa/A0001334.html.
U.S. Army Corps of Engineers, 2000, Garrison Dam/Lake Sakakawea: accessed June 21, 2001, at URL http://www.nwo.usace.army.mil/html/Lake_Proj/garrison.htm.
U.S. Geological Survey,1991, Oahe Dam and Lake Oahe: accessed June 25, 2001, at URL http://terraserver.homeadvisor.msn.com/image.asp?S=15&T=1&X=60&Y=768&Z=14&W=1.
U.S. Geological Survey, 1995, Garrison Dam and Lake Sakakawea: accessed June 25, 2001, at URL http://terraserver.homeadvisor.msn.com/image.asp?S=15&T=1&X=49&Y=822&Z=14&W=1.
U.S. Army Corps of Engineers, 2000, Oahe Dam/Lake Oahe: accessed June 21, 2001, at URL http://www.nwo.usace.army.mil/html/Lake_Proj/oahe.htm.
U.S. Geological Survey, n.d., The Missouri River Story: accessed July 6, 2001, at URL http://infolink.cr.usgs.gov/The%20River/description.htm.