The Flat River (Ottawa: Quabahquasha, "Winding Stream") is a tributary of the Grand River in the western part of the U.S. state of Michigan. It rises as the outflow of First Lake, the last in a chain of geographically close, connected lakes known as Six Lakes in Belvidere Township, west of Edmore in Montcalm County. It flows mostly south and slightly west through Montcalm County, Ionia County, and Kent County, flowing into the Grand River in Lowell. Other cities it flows through along the way include Greenville and Belding.