The Dumoine River is a river in western Quebec with its source in Machin Lake near La Vérendrye Wildlife Reserve. From Dumoine Lake, the river flows almost due south off the Canadian Shield and empties into the Ottawa River, just west of Rapides-des-Joachims, Quebec, or Rolphton, Ontario. The river is 129 kilometres (80 mi) long and drains a watershed of 5,380 square kilometres (2,080 mi). This relatively short river compared to its drainage area indicates that the Dumoine has a strong current and many steep-gradient rapids.
Primarily known today for its white water canoeing and fishing, the river has a rich history from the native Indian era to exploration, fur trading, and logging. Development is minimal along the river. Occasionally the river is crossed by logging roads but between river kilometres 20 and 30 are several cottages.