Big Sioux River

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The falls of the Big Sioux River at Sioux Falls, South Dakota
The course and watershed of the Big Sioux River.
This excerpt from the Lewis and Clark map of 1814 shows the rivers of western Iowa and eastern South Dakota. The Big Sioux River ("Sioux") is seen near the center of the map.

The Big Sioux River is a tributary of the Missouri River, 419 miles (674 km) long,[1] in eastern South Dakota and northwestern Iowa in the United States.[2] The United States Board on Geographic Names settled on "Big Sioux River" as the stream's name in 1931.[3]

The Big Sioux River rises in Roberts County, South Dakota[3] on a low plateau known as the Coteau des Prairies and flows generally southwardly through Grant, Codington, Hamlin, Brookings, Moody, and Minnehaha counties, past the communities of Watertown, Castlewood, Bruce, Flandreau, Egan, Trent, Dell Rapids, and Baltic to Sioux Falls, where it passes over a waterfall which gives that city its name. Downstream of Sioux Falls and the community of Brandon, the Big Sioux is used to define the boundary between South Dakota and Iowa, flowing along the eastern borders of Lincoln and Union counties in South Dakota, and the western borders of Lyon, Sioux and Plymouth counties in Iowa, past the communities of Canton, Fairview, Hudson, Hawarden, North Sioux City, and Dakota Dunes in South Dakota and Beloit, Hawarden and Akron in Iowa. It joins the Missouri River from the north at Sioux City, Iowa.[4][5]


The Big Sioux River collects the Rock River from the northeast in Sioux County, Iowa.[4] A minor headwaters tributary of the Big Sioux in Grant County, South Dakota, is known as the Indian River.[5][6] Broken Kettle Creek has its confluence with the Big Sioux in Plymouth County, Iowa.

Flood control[edit]

Between 1955 and 1961, an extensive flood control system was constructed along the Big Sioux and some of its tributaries in Sioux Falls to protect the city from a 100-year flood event.[7] Features of the system include 29 miles (47 km) of levees, a floodwall in downtown, and a 15,000 feet (4,600 m) diversion channel with a dam at one end and a 118-foot (36 m) spillway at the other.[7] The diversion channel connects two ends of the Big Sioux's natural loop around central Sioux Falls in an effort to channel floodwater away from the city.[7] The levees then act to contain any floodwater either remaining in the natural channel or originating from Skunk Creek (whose mouth is downriver of the diversion dam).[7][8] Additionally, a greenway covers much of the river's floodplain in southern and eastern Sioux Falls, further mitigating any property damage from high water.

See also[edit]


  1. ^ U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed March 30, 2011
  2. ^ Columbia Gazetteer of North America entry
  3. ^ a b U.S. Geological Survey Geographic Names Information System: Big Sioux River
  4. ^ a b DeLorme (1998). Iowa Atlas & Gazetteer. Yarmouth, Maine: DeLorme. ISBN 0-89933-214-5
  5. ^ a b DeLorme (2001). South Dakota Atlas & Gazetteer. Yarmouth, Maine: DeLorme. ISBN 0-89933-330-3
  6. ^ U.S. Geological Survey Geographic Names Information System: Indian River
  7. ^ a b c d "Flood Control". City of Sioux Falls. Retrieved 2010-04-19. 
  8. ^ Jorgensen, Don. Sioux Falls diverts water to ease flooding [1] KELO-TV. March 15, 2010. (accessed April 19, 2010).

External links[edit]

Coordinates: 42°29′27″N 96°26′47″W / 42.49083°N 96.44639°W / 42.49083; -96.44639