University of Manitoba - Watershed Systems Reserach Program

Lake Winnipeg Facts

Lake Winnipeg is the 10th largest freshwater lake in the world
Lake Winnipeg is the 6th largest lake in Canada
Lake Winnipeg crosses four Canadian provinces and 4 US states
Lake Winnipeg drainage basin is nearly 1,000,000km²
Lake Winnipeg basin is home to 7 million people
Only one river flows out of Lake Winnipeg – the Nelson River
Lake Winnipeg is the last remnant of glacial Lake Agassiz
Lake Winnipeg surface area is 23,750km²
Lake Winnipeg is 111km wide at its widest point
Lake Winnipeg maximum depth is 36 m
Lake Winnipeg average depth is 12m
Lake Winnipeg shoreline is 1750km long
Lake Winnipeg shoreline is 284km³
Lake Winnipeg climate is cold continental
Lake Winnipeg is the 3rd largest hydro-electric reservoir in the world (hydro-electric began in 1976)
There are between 180-195 open water days on Lake Winnipeg

Mean annual precipitation in Lake Winnipeg Watershed is 400-600mm
Snowfall represents 15-20% of total precipitation in Southern Basin
Snowfall represents 30-40% of total precipitation in Northern Basin
The average water residence time is 4.3 years for the whole of Lake Winnipeg; 1.3 years for the South Basin and 3.5 years for the North Basin
Of the 3 major rivers flowing into Lake Winnipeg, the Winnipeg river contributes 50% of the water, the Saskatchewan 25%, and the Red and Assiniboine 16%
60% of the phosphorus coming in is retained by Lake Winnipeg; 54% of N
The Red River is the largest source of total P and N, and the N and P export per hectare is highest in the Red River
Lake Winnipeg has the highest chlorophyll concentrations of any of the largest lakes in the world