When its steel gates closed on 21 January 1963, Glen Canyon Dam began turning a stretch of the Colorado River into Lake Powell. The dam is a 216-metre (710 ft) concrete arch-gravity structure in northern Arizona, near the town of Page, built by the U.S. Bureau of Reclamation between 1956 and 1966. Lake Powell holds up to 25.16 million acre-feet (31 km³), making it the second-largest artificial reservoir in the United States after Lake Mead, and it reaches 299 km (186 mi) upstream into Utah. The dam’s 1,320 MW power plant averaged 4,717 GWh a year between 1980 and 2013. Its main purpose is to store water so the Upper Colorado Basin states can meet their delivery obligations downstream, and it has been one of the most argued-over dams in American history ever since.
Floyd Dominy, David Brower and the Echo Park Bargain
The dam came out of the 1956 Colorado River Storage Project Act, and two men shaped the fight over it. Floyd Dominy, commissioner of the Bureau of Reclamation, worked Congress for the project; the writer Marc Reisner said he tended Congress like prize-winning orchids. David Brower, who led the Sierra Club, fought a companion dam at Echo Park, inside Dinosaur National Monument, which would have flooded about 180 km (110 mi) of canyons. Brower found that the Bureau had overstated how much evaporation Echo Park would save: its figure was 165,000 acre-feet a year, his no more than 19,000.
The Bureau dropped Echo Park in 1954, but the price was a dam upstream at Flaming Gorge and a larger, “high” dam at Glen Canyon to replace the lost storage. Environmentalists had not in fact been offered a straight choice between the two sites: the Bureau had always planned to build at Glen Canyon. President Dwight D. Eisenhower pressed a button in Washington on 15 October 1956 to set off the first blast at the diversion tunnel portal.
The Navajo Nation and the Manson Mesa Land Swap
The dam site lay on the Colorado Plateau more than 48 km (30 mi) from the nearest paved road, U.S. Route 89, in country used by Navajo ranchers and by miners. Much of the land the Bureau needed came through an exchange with the Navajo Nation: the tribe gave up Manson Mesa, south of the dam, in return for a similar area near Aneth, Utah, which it had long wanted. The town site of Page, 44 km² (17 sq mi) of it, came from that swap.
Before the dam was built, three federal grants paid for salvage work along the river. Historian C. Gregory Crampton and anthropologist Jesse Jennings of the University of Utah, and the Museum of Northern Arizona, recorded sites that would be flooded. One expedition, working with the Navajo Nation, found a petroglyph thought to depict the appearance of the Crab Nebula supernova in 1054.
2,500 Workers, 18 Deaths and a Town Named Page
The workforce started in a trailer camp. It grew into a company town first called Government Camp and later named Page, after John C. Page, Reclamation commissioner from 1936 to 1943. Page was planned for up to 8,000 people. At the peak of construction in 1962 nearly 2,500 people worked on the dam, and 18 died building it. Contrary to a popular myth, none were buried in the concrete.
Labour had its own dispute. Merritt-Chapman & Scott won the main contract with a bid of $107,955,552, about $30 million below the Bureau’s own estimate, and when pay was cut as public facilities in Page were completed, about 750 workers went on strike. In December 1959 wages rose by $4 a day and the strike ended. Concrete placement began on 16 June 1960, the dam was topped out on 13 September 1963, and Lady Bird Johnson dedicated it on 22 September 1966 before a crowd of 3,000 people. Page incorporated on 1 March 1975 and had 7,440 residents at the 2020 census. It now serves more than 3 million visitors a year, drawn by Lake Powell and, since 1997, by Antelope Canyon on neighbouring Navajo land.
Cathedral in the Desert and the Canyon Lost in 1963
What the lake covered was a canyon few Americans had seen. John Wesley Powell named Glen Canyon on his 1869 expedition for its carved walls, alcoves and glens. It held side canyons and springs such as Music Temple and the Cathedral in the Desert, a cave-like amphitheatre with a waterfall at its centre, and its river terraces supported as many as 316 bird species. In 1963 the Sierra Club published The Place No One Knew, with photographs by Eliot Porter, mourning the canyon as it went under. That January Brower confronted President John F. Kennedy in Washington in a last attempt to delay the flooding.
The loss changed American environmental politics. Faced with a public campaign that included a Sierra Club newspaper advertisement asking whether the Sistine Chapel should be flooded too, the Bureau abandoned plans for two Grand Canyon dams, at Marble Canyon and Bridge Canyon, in 1968. The coal-fired Navajo Generating Station was built near Page to make up the lost power; it closed in 2019. Edward Abbey’s 1975 novel The Monkey Wrench Gang made Glen Canyon Dam its saboteurs’ target, and on 21 March 1981 Earth First! unrolled a 91-metre black plastic “crack” down the dam’s face.
Seven States, Mexico and 8.23 Million Acre-Feet a Year
The people the dam serves are spread across seven states and two countries. The 1922 Colorado River Compact gave the Upper Basin (Colorado, Wyoming, Utah and New Mexico) and the Lower Basin (Arizona, California and Nevada) 7.5 million acre-feet a year each, and a 1944 treaty guaranteed Mexico 1.5 million acre-feet for Baja California and Sonora. The total was based on flow records from an unusually wet period; the river’s dependable flow at Lees Ferry is now put at about 13.5 to 14.6 million acre-feet.
Glen Canyon Dam lets the Upper Basin meet its share without rationing. It must release at least 8.23 million acre-feet a year, averaged over ten years, and in wet years it stores surplus runoff. Its defenders, Dominy among them in a 2011 interview, point to the 2000–2004 drought, the lowest five-year runoff then on record, when releases from Lake Powell are said to have kept Lake Mead from going dry.
Five Million Power Customers and a Cash Register Dam
Hydropower paid off the bonds that built the dam and helps fund other Reclamation work, which is why Glen Canyon has long been called a “cash register” dam. Its eight generators of 165 MW each total 1,320 MW, after an upgrade between 1985 and 1997 raised the plant from its original 950 MW. The power, sold by the Western Area Power Administration since 1977, reaches about 5 million people in Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming.
Output depends on how much water flows and on how high the lake stands, since a fuller reservoir gives more head on the turbines. At the foot of the dam an 8,000 m² Kentucky bluegrass lawn covers the buried penstocks, which were covered with soil to damp their vibration.
Humpback Chub, Grand Canyon Sandbars and a Dry Delta
Downstream, the costs fall on the river itself. Before the dam, the Colorado ranged from over 27 °C in summer to near freezing in winter; water released from deep in Lake Powell now runs at about 8 °C all year, clear and cold, conditions hostile to native fish such as the humpback chub and Colorado pikeminnow. About 100 million US tons of sediment a year are trapped behind the dam, so the sandbars of the Grand Canyon erode without replacement. Power-driven swings in release, which could double or triple the river in an hour, stranded boaters until temporary limits in 1990 and a 1995 environmental impact statement capped flows and hourly changes, restrictions estimated to cost $38 million to $58 million a year in power revenue between 1997 and 2005. The first of the “high flow experiments” on 26 March 1996 sent 45,000 cubic feet per second down the canyon to rebuild beaches.
Far to the south, the Colorado River Delta in Mexico once received 4 to 6 million acre-feet a year. Once the dam allowed more upstream use, that fell away in normal years, and about 7,800 km² (3,000 sq mi) of wetlands have disappeared.
Evaporation, the 1983 Flood and the Record Lows of 2022 and 2023
The lake loses a great deal of water. The Glen Canyon Institute estimates average losses to evaporation and seepage at 860,000 acre-feet a year, about 6 per cent of the river’s flow; in water year 2015, with the lake about half full, evaporation was 368,000 acre-feet. The El Niño floods of 1983 came close to endangering the dam itself: cavitation tore through both spillway tunnels, and the lake peaked on 14 July at 3,708.34 ft (1,130.30 m), a level not exceeded since. Repairs cost about $15 million.
The megadrought has pushed the other way. On 22 April 2022 Lake Powell fell to 3,522.24 ft (1,073.58 m), just 22.88 per cent full, and on 13 April 2023 it sank lower still, to 3,519.92 ft. Levels like these have lent weight to “Fill Mead First”, a proposal to drain Lake Powell and hold the water downstream in Lake Mead instead. How the two reservoirs share the river is explained in our guides to Lake Powell and Hoover Dam, and the effects on the canyon below appear in our Grand Canyon geography guide.