It is located in southwestern Minnesota within Lincoln, Lyon, Murray, Pipestone, Redwood, and Yellow Medicine counties. There are 14 municipalities in the watershed of which the city of Marshall is the largest. The Redwood River major watershed area is approximately 705 square miles or 451,257 acres. The watershed is subdivided into 52 minor watersheds. The minor watersheds range in size from 3,230 acres to 27,331 acres with the mean size approximately 8,678 acres.
Agriculture is the predominant land use within the watershed.
The Redwood River and its tributaries, public and private drainage systems, lakes and wetlands, define the drainage network of the major watershed. The Redwood River flows north and east to its confluence with the Minnesota River near Redwood Falls in Redwood County. The total distance of the stream network is 924 miles of which 674 miles are intermittent streams and 250 miles are perennial streams.