Where Does the Water Flow?

For a map of all the watersheds in the Northwest Territories (NWT), click here.

The majority of rivers and lakes within the NWT are situated within the Mackenzie River watershed, Canada’s largest river basin.  Within the Mackenzie River watershed, the Slave River carries the largest quantity of water into the NWT and 77% of the water entering the Great Slave Lake. The Slave River flows into Great Slave Lake through the Slave River Delta, an area that is rich in wildlife, and both culturally and economically important to residents in nearby communities. Water flows into the lake through a series of channels, including four main channels: ResDelta, Old Steamboat Channel, Middle Channel and East Channel.

Access full size map here.

In addition to the inflow provided by the Slave River, the Taltson, Lockhart and Hay Rivers together contribute approximately 11% of water entering Great Slave Lake, while the remaining 12% is provided by ten other smaller drainage areas. At 28,570 km2, Great Slave Lake is North America’s fifth largest lake and is the deepest at 614 m. The Mackenzie River is Canada’s longest river at 1802 km in length, and flows northwest from Great Slave Lake through the NWT to the Beaufort Sea. It is an important transportation corridor for the communities situated in the Mackenzie Valley. Great Bear Lake is the largest freshwater lake located entirely within Canada. Great Bear River originates from Great Bear Lake and flows into the Mackenzie River.

The Mackenzie Delta is the world’s second largest arctic delta and provides habitat for many fish, mammal and bird species, including endangered species. North America’s largest freshwater discharge to the Arctic Ocean flows through the Mackenzie Delta. To see a map of the two deltas in the NWT click here.

There are many other major rivers within the Mackenzie River Basin including the Liard and Peel Rivers, as well as countless smaller rivers, lakes and wetlands. The headwaters of many important rivers are within the NWT. The Kazan, Dubawnt, Thelon, Back and Coppermine rivers all flow from the NWT into Nunavut, while the Anderson, Horton and Hornaday rivers flow directly into the Beaufort Sea.