Mackenzie River - Human Use

Human Use

As of 2001, approximately 397,000 people lived in the Mackenzie River basin – representing only 1% of Canada's population. Ninety percent of these people lived in the Peace and Athabasca River drainage areas, and mainly in Alberta. The cold northern permafrost regions beyond the Arctic Circle are very sparsely populated, mainly by indigenous peoples. As a result, much of the Mackenzie watershed is comprised by unbroken wilderness and human activities presently little influence on water quality and quantity in the basin's major rivers. Perhaps the heaviest use of the watershed is in resource extraction – oil and gas in central Alberta, lumber in the Peace River headwaters, uranium in Saskatchewan, gold in the Great Slave Lake area and tungsten in the Yukon. Especially in the case of oil, these activities are beginning to pose a threat to riverine ecology in the headwaters of the Mackenzie River.

During the ice-free season, the Mackenzie is a major transportation link through the vast wilderness of northern Canada, linking the numerous scattered and isolated communities along its course. Canada's northernmost major railhead is located at the town of Hay River, on the south shore of Great Slave Lake. Goods shipped there by train and truck are loaded onto barges of the Inuit-owned Northern Transportation Company. Barge traffic travels the entire length of the Mackenzie in long "trains" of up to fifteen vessels pulled by tugboats, with the sole exception being in a few of the river's narrows, where the barges are uncoupled and towed one by one through difficult stretches. Goods are shipped as far as the town of Tuktoyaktuk on the eastern end of the Mackenzie Delta. From there they are further distributed among communities along Canada's Arctic coast and the numerous islands north of it. During the winter, the frozen channel of the Mackenzie River, especially in the delta region, is crisscrossed with ice roads served by dogsleds and snowmobiles.

Although the entire main stem of the Mackenzie River is undammed, many of its tributaries and headwaters have been developed for hydroelectricity production, flood control and agricultural purposes. The W.A.C. Bennett Dam and Peace Canyon Dam on the upper Peace River were completed in 1968 and 1980 for power generation purposes. The two dams, both owned by BC Hydro, have a combined capacity of more than 3,400 megawatts (MW). The reservoir of W.A.C. Bennett – Williston Lake – is the largest body of fresh water in BC and the ninth largest man-made lake in the world, with a volume of 70.3 km3 (57,000,000 acre·ft). Williston's additional purpose of flood control has led to reduced flooding in the Peace River valley, the Peace-Athabasca Delta, and the Slave River, which while providing for better farming conditions, has had significant impacts on wildlife and riparian communities. The decrease in annual flow fluctuations has had impacts as far downstream as the main stem of the Mackenzie.

Agriculture in the Mackenzie River basin is mainly concentrated in the southern portion of the watershed, namely the valleys of the Peace and Athabasca Rivers. The valley of the former river is considered to be some of the best northern farmland in Canada. These conditions are expected to be improved even more by recent trends in climate change, such as warmer temperatures and a longer growing season. It is even said that "there is enough agricultural capability in the Peace River Valley to provide vegetables to all of northern Canada". However, reaches of the Peace River Valley are threatened with flooding by the proposed Site C Dam, which would generate enough electricity to power about 460,000 households. Site C has been the center of a protracted and ongoing environmental battle since the 1970s, and a decision has not yet been reached as to whether or not to build the dam.

Site C is not the only proposed water project in the Mackenzie basin. A potential US$1 billion run-of-the-river hydroelectricity station on the Slave River would generate at least 1,350 MW of power. Some tentative proposals have gone as far as to include dams on the main stem of the Mackenzie itself. By far the largest engineering project ever slated for the Mackenzie River was the North American Water and Power Alliance (NAWAPA), a vast series of dams, tunnels and reservoirs designed to move 150 km3 (120,000,000 acre·ft) of Arctic meltwater to southern Canada, the western United States and Mexico. The system would involve building massive dams on the Liard, Mackenzie, Peace, Columbia, and Fraser rivers, then pumping water into a 650 km (400 mi) long reservoir in the Rocky Mountain Trench. The water would then flow by gravity to irrigate more than 220,000 km2 (85,000 sq mi) in the three countries and generate more than 50,000 MW of surplus energy. First proposed in the 1950s, the project's estimated cost has since risen to over $200 billion. Because of its massive cost and environmental impacts, it is considered unlikely to ever be implemented.