James River

The James River (also known as the Jim River or the Dakota River) is a tributary of the Missouri River, approximately 710 miles (1,140 km) long, draining an area of 20,653 square miles (53,490 km) in the U.S. states of North Dakota and South Dakota. About 70 percent of the drainage area is in South Dakota. The river provides the main drainage of the flat lowland area of the Dakotas between the two plateau regions known as the Missouri Coteau and the Coteau des Prairies. This narrow area was formed by the James lobe of the Laurentide Ice Sheet during the last ice age, and as a consequence the watershed of the river is slender and it has few major tributaries for a river of its length.

The James drops approximately 5 inches (130 mm) per 1 mile (1.6 km), and this low gradient sometimes leads to reverse flow. Reverse flow occurs when high inflow from tributaries leads to James River water flowing upstream for several miles above the joining water. This happens most frequently north of Huron, South Dakota.