The Fall River, also called the South Verdigris River, rises at the confluence of two headstreams in southeastern Kansas. It flows for 90 miles through Greenwood, Elk, and Wilson Counties. The source of the river is in west Greenwood County, approximately 4.5 miles northwest of Eureka. It is a tributary of the Verdigris River, and its confluence with the Verdigris is approximately two miles south of Neodesha.
In the city of Fall River, in southeastern Greenwood County, the river is dammed to form Fall River Lake, used for flood control and irrigation. Fall River State Park is located on this lake.