The Redwood River is located in southwestern Minnesota in the counties of Lincoln, Lyon, Murray, Pipestone, Redwood, and Yellow Medicine. It begins near Ruthton in northeast Pipestone County, and flows about 125 miles northeast through Redwood Lake and to the Minnesota River at North Redwood. The watershed covers 451,250 acres or 705 square miles. There are 11 incorporated communities located within the watershed, including Marshall, Redwood Falls, Tyler, Russell, and Vesta, and three unincorporated communities.
The Redwood River watershed is one of 13 major watersheds in the Minnesota River Basin. The entire Redwood River watershed has 85.5% of the land in cultivation (approximately 385,665 acres), 7% in grassland, 1.5% in water, and 0.6% in wetlands. Altitudes descend from west to east, with the Coteau des Prairies serving as a watershed divide. Natural drainage patterns in the area were established by valleys formed from glacial meltwaters. End moraines, which were formed during the recession of the last glacier, are the most prominent features. Counties in the watershed include Lincoln, Yellow Medicine, Lyon, Murray, Redwood, and Cottonwood.