Big Sioux River

The Big Sioux River rises in Roberts County, South Dakota<ref name=GNIS/> on 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, North Sioux City, and Dakota Dunes in South Dakota and Hawarden and Akron in Iowa. It joins the Missouri River from the north at Sioux City, Iowa.<ref name=DeLormeIA>DeLorme (1998). Iowa Atlas & Gazetteer. Yarmouth, Maine: DeLorme. ISBN 0-89933-214-5</ref><ref name=DeLormeSD>DeLorme (2001). South Dakota Atlas & Gazetteer. Yarmouth, Maine: DeLorme. ISBN 0-89933-330-3</ref>

[edit] Tributaries

The Big Sioux River collects the Rock River from the northeast in Sioux County, Iowa.<ref name=DeLormeIA/> A minor headwaters tributary of the Big Sioux in Grant County, South Dakota, is known as the Indian River.<ref name=DeLormeSD/><ref>Geographic Names Information System entry for Indian River</ref>