Canada’s prairie inland sea drains four provinces toward Hudson Bay
Lake Winnipeg covers 24,514 square kilometres in Manitoba—Earth’s twelfth-largest lake and Canada’s sixth-largest freshwater body. Its watershed is the country’s largest lake catchment, gathering water from four provinces and four U.S. states before the Nelson River runs north to Hudson Bay.
The southern tip lies about fifty-five kilometres north of Winnipeg city. North–south length reaches 416 kilometres past sandy beaches, limestone cliffs, and bat caves. East-side boreal rivers joined the 2018 UNESCO site Pimachiowin Aki. Manitoba Hydro treats the lake as a major reservoir in its generating system.
Inflows arrive via the Saskatchewan, Red, Winnipeg, and other rivers from Alberta, Saskatchewan, Ontario, Manitoba, plus North Dakota, Minnesota, South Dakota, and Montana headwaters. The Saskatchewan arrives from the west through Cedar Lake, the Red, carrying the Assiniboine, comes up from the south, and the Winnipeg River brings the outflow of Lake of the Woods and Rainy Lake from the south-east, while the Dauphin River delivers water from Lake Manitoba. Mean Nelson outflow runs about 2,066 cubic metres per second through what was once Rupert’s Land under Hudson’s Bay Company charter.
Both Lake Winnipeg and Lake Manitoba are leftovers of the vast prehistoric Glacial Lake Agassiz, though the southern basin appears to have dried out about 4,000 years ago. The land between them is called the Interlake, part of the wider Manitoba Lowlands.
No Canadian lake west of the Great Lakes holds more kinds of fish: 60 of Manitoba’s 79 native species occur here, including the at-risk shortjaw cisco and bigmouth buffalo. Newcomers keep arriving, from common carp that came down the Red River to white bass, first caught in 1963 a decade after their release in North Dakota, and smallmouth bass, first noted in 2002. Stocked rainbow and brown trout cannot breed on their own here.
Source: Lake Winnipeg
