the way or turned back before reaching the Yukon. Oil was discovered at Norman Wells in the 1920s, beginning a period of industrialization in the Mackenzie valley. Oil was initially shipped out by steamboats, supplying mines and towns across the NWT. This demand grew when gold was discovered on the northern shore of Great Slave Lake, leading to the settlement of Yellowknife and the opening of several mines in the area. By the 1940s steamboats had been replaced by modern gas and diesel-powered craft, which continue to serve the river today. During World War II oil pumped in Norman Wells was shipped to Fairbanks, Alaska via the Canol pipeline. The pipeline was considered a "fiasco", going five times over budget and losing as much as 20 percent of the oil due to poor construction. It only operated for thirteen months, shutting down in 1945. Much abandoned equipment remains along the corridor today; part of the pipeline route has been designated the Canol Heritage Trail. In 1964 the Mackenzie Northern Railway (now a subsidiary of CN) reached the shore of Great Slave Lake, to serve the new Pine Point zinc mine near Hay River. Although the mine shut down in 1988, the railroad remains an important transportation link between the Mackenzie River waterway and the rest of Canada. In the 1950s the U.S. Army Corps of Engineers proposed the North American Water and Power Alliance (NAWAPA), a vast series of dams, tunnels and reservoirs designed to move of water from northern Canada to southern Canada, the western United States and Mexico. The system would involve building massive dams on the Liard, Mackenzie, Peace, Columbia, and Fraser river systems and pumping water into a long reservoir in the Rocky Mountain Trench. The water would then flow by gravity to irrigate more than in the three countries and generate more than 50,000 MW of surplus energy. The projects were never built due to the massive cost and environmental impact. The Royal Canadian Mint honoured the 200th anniversary of the naming of the Mackenzie River with the issue of a silver commemorative dollar in 1989. In 1997, a cultural landscape along the section of the Mackenzie River at Tsiigehtchic was designated the Nagwichoonjik (Mackenzie River) National Historic Site of Canada due to its cultural, social and spiritual significance to the Gwichya Gwich'in. In 2008, Canadian and Japanese researchers extracted a constant stream of natural