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Image by John Gibbons

About Glen Canyon Dam

The Full Story

Glen Canyon Dam, rising 710 feet above bedrock within the steep, rust-colored sand-stone walls of Glen Canyon, was constructed to harness the power of the Colorado River in order to provide for the water and power needs of millions of people in the West.Glen Canyon Dam is the second highest concrete-arch dam in the United States, second only to Hoover Dam which stands at 726 feet. The 27 million acre-feet of water storage capacity in Lake Powell, created by Glen Canyon Dam, serves as a ‘bank account’ of water that is drawn on in times of drought. This stored water has made it possible to successfully weather extended dry periods by sustaining the needs of cities, industries, and agriculture throughout the West.

Hydroelectric power produced by the dam’s eight generators helps meet the electrical needs of the West’s rapidly growing population. With a total capacity of 1,320 megawatts, Glen Canyon Powerplant produces around five billion kilowatt-hours of hydroelectric power annually which is distributed by the Western Area Power Administration to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada, and Nebraska. In addition, revenues from production of hydropower help fund many important environmental programs associated with Glen and Grand canyons.

The designation of Glen Canyon National Recreation Area in 1972, underscores the value and importance of the recreation benefits associated with Lake Powell and the Colorado River downstream of the dam. The recreation area is managed by the National Park Service.

Glen Canyon Dam is the key water storage unit of the Colorado River Storage Project, one of the most complex and extensive river resource developments in the world. Without it, development of the Upper Colorado River Basin states’ portion of the Colorado River would not have been possible.

The concrete arch dam has a crest length of 1,560 feet and contains 4,901,000 cubic yards of concrete. Thickness of the dam at the crest is 25 feet, and the maximum base thickness is 300 feet.

A separate spillway is constructed in each abutment. Each spillway consists of an intake structure with two 40- by 52.5-foot radial gates and a lined spillway tunnel. The downstream portions of the spillway tunnel were used during construction as diversion tunnels. Each spillway tunnel reduces in size from 48 to 41 feet in diameter. The combined spillway discharge capacity is 208,000 cubic feet per second at an elevation of 3,700.0 ft.

The outlet works near the left abutment of the dam consist of four 96-inch-diameter pipes. Each outlet is controlled by one 96-inch-ring follower gate and one 96-inch hollow-jet valve. The combined river outlet works capacity is 15,000 cubic feet per second.

Total capacity for Lake Powell is 27 million acre-feet, and the active capacity is 20,876,000 acre-feet. At normal water surface elevation, the reservoir has a length of 186 miles and a surface area of 161,390 acres.

The power plant at the toe of the dam consists of four 118,750-kilowatt and four 136,562-kilowatt generators driven by eight turbines. Total nameplate generating capacity for the powerplant is 1,021,248 kilowatts. Eight penstocks through the dam convey water to the turbines. Each penstock reduces in size from 15 to 14 feet in diameter.