HELLS CANYON

gorge of the Snake River in the United States, forming part of the Idaho-Oregon boundary, between the Seven Devils and Wallowa mountains. It has a total length of 125 miles (201 km), along 40 miles (64 km) of which it is more than a mile deep. A maximum depth of 7,900 feet (2,400 m) makes it the deepest gorge on the North American continent. Parts of the canyon are richly coloured in shades of yellow, red, and orange, and in places the walls rise perpendicularly for several thousand feet. After much controversy between public and private power advocates over damming the Snake River (to help contain downstream floods in the Columbia River), the Idaho Power Company completed three dams in the area-Brownlee (1959), Oxbow (1961), and Hells Canyon (1968). The Hells Canyon-Seven Devils Scenic Area is divided between Wallowa-Whitman National Forest (Oregon) and Nezperce and Payette national forests (Idaho). Hells Canyon, with its surrounding area (662,000 acres [268,000 hectares]), was designated a national recreation area in 1975.