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.
Geography of Canada
The northern parts of Alberta, Manitoba and British Columbia, most of Northwest Territories and Nunavut, and parts of Yukon are drained by the Arctic watershed. This watershed has been little used for hydroelectricity, with the exception of the Mackenzie River, the longest river in Canada. The Peace, Athabasca and Liard Rivers, as well as Great Bear Lake and Great Slave Lake (respectively the largest and second largest lakes wholly enclosed by Canada) are significant elements of the Arctic watershed. Each of these elements eventually merges with the Mackenzie, thereby draining the vast majority of the Arctic watershed.