The Mackenzie River, originating in the Great Slave Lake in the Northwest Territories, is longest river in Canada flowing freely for about 1700 km before draining into the Arctic Ocean. Flow is south to north and drains an area over 1.8 million km2 which represents one sixth the area of Canada. For only five months of the year can the river be navigated, because in early November it freezes over. During the winter months sections of the river function as ice roads. Only in May does ice break-up generally occur. The benefit of this harsh climate means the area is largely unspoilt and is very sparsely populated. Where the river enters the ocean an extensive delta has grown which forms a maze of interconnecting channels.
The Mackenzie River valley has large areas of permafrost which lies only a few feet beneath the subsurface of the islands in the delta. Consequently the Mackenzie River valley is one area in Canada selected by the Integrated Research and Monitoring Area programme (IRMP), as a region sensitive to climate change. The IRMP programme will assess the response of landscape altering processes to a warmer climate.