 It rises southwest of Balaton in Rock Lake Township in southern Lyon County, as an intermittent stream on the Coteau des Prairies, a morainic plateau dividing the Mississippi and Missouri River watersheds.The river flows off the Coteau in a wooded valley in southeastern Lyon County, dropping 200 feet (60 m) in five miles (3 km), and enters a region of till plains, flowing through southern Redwood County, the northeastern corner of Cottonwood County, and northern Brown County, past the communities of Sanborn and Springfield.It enters a wooded valley near its mouth, flowing through Flandrau State Park and entering the Minnesota River just southeast of New Ulm.