Couse Creek rises in Matheny Gully in southeast Asotin County and flows northeast to the Snake River south of Grahams Landing. The stream was named for the abundance of Cous Biscuit-root (Lomatium cous), which has globular tubers, is edible, and was used by Native Americans for making bread. The Native American name in common use was Kowish, a Nez Perce word.