Trois-Rives is a municipality with an area of 675 square kilometres (261 sq mi) located in Mékinac Regional County Municipality, in the Mid-Mauricie, province of Quebec, Canada.It is bounded on the west by the Saint-Maurice River, and includes the communities of Grande-Anse, Olscamps, Rivière Matawin (Hamlet), Saint-Joseph-de-Mékinac and partially Rivière-aux-Rats.