river, 180 mi (290 km) long, rising in the low prairie country near the Little Missouri River, SW N.Dak., and flowing E to the Missouri at Mandan, N.Dak. The Heart Butte and Dickinson dams, irrigation and flood control units built by the U.S. Bureau of Reclamation as part of the Missouri River basin project, have created the region’s largest lakes, which are major recreation areas.
