MACKENZIE RIVER

seasonal tributary of the Fitzroy River, eastern Queensland, Australia. Formed by the junction of the Comet and Nogoa rivers, which rise in the Eastern Highlands, it flows for 170 miles (275 km) past Comet, northeast across the Expedition Range, and then southeast, joining the Dawson River to form the Fitzroy River. Its principal tributary is the Isaac. Explored in 1844 by Ludwig Leichhardt, it was named after Sir Evan Mackenzie, a Queensland settler. Its valley supports dairy and beef cattle. river system of northwestern North America, a major element in the drainage pattern of the continent. It issues from Great Slave Lake in the Northwest Territories of Canada and flows generally northward through Fort Smith and Inuvik regions to the Beaufort Sea of the Arctic Ocean. Its basin, with an area of 697,000 square miles (1,805,200 square km), is the largest in Canada and is exceeded on the continent only by the Mississippi-Missouri system. The Mackenzie itself is 1,025 miles (1,650 km) long, according to the conventional measurement from Great Slave Lake. If the Finlay River, its farthest headstream, which flows into the Peace River Reservoir west of the Rocky Mountains, is included, however, the entire river system runs for 2,635 miles (4,241 km) through the sparsely settled, lake-strewn Canadian north country. The river is generally wide, mostly from 1 to 2 miles (1.5 to 3 km) across; in its island-dotted sections it is 3 to 4 miles (5 to 6.5 km) wide. The headwaters of the system include several large rivers that drain the vast forested plains of northeastern British Columbia and northern Alberta, among them the Liard, Peace, and Athabasca rivers. Shorter rivers flow into the system from the east, draining the low rocky hills of the Canadian Shield. The system also includes the huge Great Slave and Great Bear lakes. The Mackenzie River basin is sparsely populated, and its natural resources are few and largely inaccessible. As a result, the unspoiled region offers abundant wildlife and spectacular scenery. The large lakes of the Mackenzie basin are a source of lake trout and whitefish. Limited lumber and agricultural products are produced, mostly in the southern part of the basin. Minerals are the economic basis of some of the larger settlements. The first oil field was discovered at Norman Wells in 1921. Others were found in the early 1970s near the Mackenzie River delta, and large reserves lie in the Athabasca Tar Sands along the Athabasca River north of Fort McMurray. Oil is carried southward by pipeline to Edmonton, Alta., where it is distributed to refineries in southern Canada and the northern United States. The water of the Mackenzie River system was too far away from large industrial and urban markets to be used for hydroelectric power until the late 1960s, when the Peace River was dammed. There are other developed waterpower sites on the Snare and Taltson rivers. The Alaskan mountain ranges and the Mackenzie and Yukon river basins and their drainage networks. major river system in the drainage pattern of northwestern North America. Its basin is the largest in Canada, and it is exceeded on the continent only by the Mississippi-Missouri system. The Mackenzie system drains an area of some 697,000 square miles (1,805,200 square kilometres), which is almost as large as Mexico. From the headwaters of the Finlay River, which flows into Williston Lake (the impounded waters of the Peace River) west of the Rocky Mountains, the entire river system runs for 2,635 miles (4,241 kilometres) through the lake-strewn Canadian north to empty into the cold waters of the Beaufort Sea in the Arctic Ocean. The Mackenzie itself is 1,025 miles long, according to the conventional measurement from Great Slave Lake. The river is generally wide, mostly from 1 to 2 miles across, and in island-dotted sections, 3 to 4 miles wide. It has a strong flow. Its lake-covered triangular delta measures more than 120 miles from north to south and is about 50 miles wide along the Arctic shore. The headwaters of the system include several large rivers, which themselves drain vast forested plains of northeastern British Columbia and northern Alberta. These drainage basins include the Liard River (about 107,000 square miles), the Peace River (116,800 square miles), and the Athabasca River (36,800 square miles). Much shorter rivers flow into the system from the east, draining the low rocky hills of the ancient structural mass known as the Canadian Shield. The system also includes the huge Great Slave Lake (11,030 square miles), Great Bear Lake (12,100 square miles), and the smaller Lake Athabasca (3,060 square miles). The whole region is subject to a harsh winter climate, and its resources are few and less accessible than those of southern Canada. Yet it is one of the few great unspoiled areas of the world, offering a varied wildlife and spectacular scenery. Additional reading Mackenzie River Basin Committee (Canada), Mackenzie River Basin Study Report (1981), examines the development of water and related resources. Environmental aspects are treated in Thomas R. Berger, Northern Frontier, Northern Homeland: The Report of the Mackenzie Valley Pipeline Inquiry, rev. ed. (1988), which also includes a survey of the Native American population of the area. James K. Smith, The Mackenzie River: Yesterday's Fur Frontier, Tomorrow's Energy Battleground (1977), surveys the economic history of the Mackenzie River valley. Robin Minion (compiler), Communities and Towns of the Northwest Territories (1985), looks at the modern situation. T. Fenge et al., Land Use Programs in Canada: Northwest Territories (1979), is also worth consulting. J. Lewis Robinson