Mackenzie River
At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the watershed, reaching up to deep in the Mackenzie Delta. As a whole, the Mackenzie basin receives only meager to moderate rainfall, averaging over the entire basin, though mountain areas experience much higher precipitation, and areas near and north of the Arctic Circle receive much lower precipitation.
Pollution in Canada
Pollution of the Great Lakes, the world’s biggest bodies of fresh water, continue to be a significant problem for both Canada and the United States. According to Derek Stack, executive director of Great Lakes United, "High pollution levels in the Great Lakes basin continue to take an apparent toll on the air and water quality of the ecosystem." 
In 2002, it was reported that the Great Lakes basin was home to 45% of all toxic air pollution in Canada, in turn affecting the Great Lakes' water. An even more recent report suggests that the Alberta oil sands' impact could reach as far as the Great Lakes. The report warns that "[oil] refineries will be using the Great Lakes ‘as a cheap supply’ source for their copious water needs and the area’s air ‘as a pollution dump'."