Winnipeg River is a Canadian river that flows roughly northwest from Lake of the Woods in the province of Ontario to Lake Winnipeg in Manitoba. This river is 235 kilometres (146 mi) long from the Norman Dam in Kenora to its mouth at Lake Winnipeg. Its watershed is 106,500 square kilometres (41,100 sq mi) in area, mainly in Canada. About 29,000 square kilometres (11,000 sq mi) of the watershed is in northern Minnesota, United States.

Lake of the Woods is a lake occupying parts of the Canadian provinces of Ontario and Manitoba and the U.S. state of Minnesota. Lake of the Woods is over 70 miles (110 km) long and wide, containing more than 14,552 islands and 65,000 miles (105,000 km) of shoreline. It is fed by the Rainy River, Shoal Lake, Kakagi Lake and other smaller rivers. The lake drains into the Winnipeg River and then into Lake Winnipeg. Ultimately, its outflow goes north through the Nelson River to Hudson Bay.