The hydro giants
The biggest machines on the map run on falling water. A story in 6 stops on the Wattlas map of the North American grid.
The Columbia River
The Columbia rises in the Canadian Rockies and runs more than a thousand miles to the Pacific, gathering snowmelt from seven states and a province and losing height all the way. For thousands of years its great landmark was Celilo Falls, just upstream of The Dalles, where the peoples of the plateau fished for salmon from wooden platforms hung over the roaring water. The federal government saw another kind of wealth in all that falling water. Bonneville Dam, the first federal dam on the lower river, began generating in 1938, and the Bonneville Power Administration had been created to sell its power. More dams followed, one behind the next, until the river became a staircase of reservoirs, and when The Dalles Dam closed its gates in March 1957 the rising water silenced Celilo Falls within hours. BPA says the Northwest's dams produce more electricity than any other North American river system. EIA put the Columbia basin at 44% of US hydroelectric generation in 2012. The largest of all its dams stands far upstream, where the river bends through the dry scablands of eastern Washington.
On the map: Dams step down the Columbia and its tributaries. John Day (2,052 MW) and The Dalles (1,823 MW) sit on the river here; Chief Joseph (2,456 MW) and Grand Coulee are upstream. Washington and Oregon hold 133 hydro plants on the map, about 30 GW.
Sources: BPA, EIA, Wikipedia, Celilo Falls
Grand Coulee
Eastern Washington in the early 1930s was dry wheat country, and the Columbia ran past it at the bottom of a canyon, far below the fields that needed its water. Local boosters had argued for years over how to lift it out, and the Depression settled the matter, because a dam big enough to do it would also put thousands of men to work. Ground was broken on July 16, 1933. What rose over the next eight years was then the largest concrete structure in the world, with pumps planned to lift river water into the Grand Coulee and spread it across the Columbia Basin, and later additions would stretch it to nearly a mile. In the spring of 1941 the Bonneville Power Administration hired a young Oklahoma singer named Woody Guthrie, drove him up and down the river, and got 26 songs out of him in about a month, among them "Roll On, Columbia" and "Grand Coulee Dam." Pearl Harbor came weeks before Reclamation accepted the finished dam on January 1, 1942, and its power went to war. It ran aluminum smelters, Boeing's bomber plants, the Portland shipyards and, from 1944, the secret plutonium reactors at Hanford. A third powerhouse, finished in 1974, made Grand Coulee the largest power station in the United States.
On the map: The map's data lists Grand Coulee at 7,079 MW, the most of any operating plant on the map. The Bureau of Reclamation gives more than 6,809 MW.
Sources: National Park Service, Reclamation, Wikipedia, Grand Coulee Dam, Wikipedia, Roll On, Columbia, Roll On
Hoover Dam
Grand Coulee had a model to follow, far to the south and a few years older. The Colorado River flooded the farms of the Imperial Valley in wet years and ran thin in dry ones, and Southern California wanted both its water and its power. President Coolidge signed the Boulder Canyon Project Act on December 21, 1928, and in 1931, in the worst years of the Depression, thousands of men poured into Black Canyon looking for work. Many camped in a squatters' settlement called Ragtown before the government town of Boulder City was ready, and that first summer the daytime highs averaged nearly 120 degrees. They finished more than two years ahead of schedule. Franklin Roosevelt dedicated the dam in September 1935, and the first generator went into full operation on October 26, 1936, sending power west across the Mojave to Los Angeles. Behind the dam rose Lake Mead, the largest reservoir in the country and the fuel for every turbine below it. Two decades of drought have drawn it down. In July 2022, Lake Mead stood at its lowest level since 1937, when the reservoir was still filling for the first time, and a white band of bare rock ringed its shore to show how far the water had fallen.
On the map: The map lists Hoover Dam twice, a Nevada entry and an Arizona entry of about 1,039 MW each. Together they come to the roughly 2,080 MW the Bureau of Reclamation gives for the whole plant.
Sources: Reclamation history, Reclamation power FAQ, NASA, USGS, Wikipedia, Hoover Dam
Churchill Falls
Hoover and Grand Coulee were built by governments with a nation behind them. The great falls of Labrador had no such backer, and nobody nearby to buy their power. At Grand Falls the Hamilton River drops more than 300 meters in less than 32 kilometers, and a surveyor had sketched a way to harness it as early as 1915, but the site lay deep in the wilderness, far from any city that could use the power. In 1953 Premier Joey Smallwood helped create Brinco, backed by British bankers and industrialists, to develop Labrador's resources, and it spent sixteen years trying to finance a project with no market. Quebec would not let Labrador power cross its territory to reach anyone else. By 1969 Brinco's money was running out while Hydro-Québec's was not, and the contract the two sides signed sold about 31 billion kilowatt hours a year for 40 years at around 3 mills, three tenths of a cent, falling to about 2.5 mills, then renewed itself automatically for 25 more years at 2 mills. Work had begun in July 1967, then the largest civil engineering project ever undertaken in North America. Crews hollowed a powerhouse out of solid granite some 300 meters underground, and 88 dikes stretching 64 kilometers held back the Smallwood Reservoir. The first units delivered power in 1971, and by 1974 the station, on a river renamed for Winston Churchill, was in full production. As power prices climbed, Quebec's windfall became Newfoundland and Labrador's lasting grievance, and in 2018 the Supreme Court of Canada refused to reopen the contract before 2041. The flooding, done without any agreement with the Innu, destroyed their hunting grounds and burial sites. In September 2026 the province's legislature voted 21 to 18 to move ahead with a new agreement with Hydro-Québec.
On the map: Churchill Falls is 5,428 MW, the third-largest operating plant on the map, after Grand Coulee and Robert-Bourassa. Muskrat Falls, 824 MW, sits downstream to the east.
Sources: Newfoundland and Labrador Heritage, CBC News, Wikipedia, Churchill Falls Generating Station
James Bay
Robert Bourassa won Quebec in 1970 on a promise of 100,000 jobs, and he went looking for them in the north. The rivers that drain into James Bay run through a vast country of spruce, rock and lakes, home to the Cree, and no one had tried to dam them on anything like the scale he had in mind. Bourassa launched the James Bay project on April 30, 1971, and called it the project of the century. Nobody had asked the Cree or the Inuit. They went to court, and in November 1973 a Quebec judge ordered the work stopped. An appeals court lifted the order within days, yet the case had made its point, and the governments came to the table. The James Bay and Northern Quebec Agreement, signed on November 11, 1975, was Canada's first modern treaty, exchanging land claims for compensation, guaranteed hunting and fishing rights and a measure of self-government. The dams went up along La Grande River. The biggest powerhouse, LG-2, was carved deep into the rock and later renamed for the premier who launched it, and its power travels hundreds of miles south on 735 kV lines, a voltage Hydro-Québec had pioneered in the 1960s.
On the map: Robert-Bourassa (5,616 MW, the same figure Hydro-Québec gives) is the second-largest operating plant on the map, after Grand Coulee. Hydro plants step inland from James Bay, and long lines carry their power south.
Sources: Hydro-Québec history, Hydro-Québec facility, Government of Canada, Wikipedia, James Bay Project
Niagara
The story of the hydro giants began here. In 1895 the Adams plant put the falls to work for a whole industry, and for sixty years the American side of the gorge filled with private powerhouses. The largest, Schoellkopf, was built into the cliff below the falls. On June 7, 1956, water seeping through the rock behind it cracked the station's back wall, and most of the plant crashed into the river. Its loss left western New York short of power and gave Robert Moses, the most formidable builder in the state, the opening he wanted. Congress passed the Niagara Redevelopment Act in 1957, the New York Power Authority took on the job, and Moses drove it hard. The Robert Moses plant produced its first power in 1961, fed by conduits that carry the river under the city from intakes above the falls. Across the water, Ontario had chosen public power half a century earlier, when Adam Beck, a cigar-box maker turned mayor of London, Ontario, campaigned to sell Niagara's electricity at cost. Under the 1950 Niagara Treaty, the falls must keep enough water to stay a spectacle, more by day in the tourist season, and the water left after the falls' minimum flows is split equally between the two countries for power. The Adams plant proved that falling water could power an industry, and the giants that followed on the Columbia and La Grande now each draw more power from their rivers than both nations take from the falls.
On the map: Robert Moses Niagara is 2,435 MW on the map; the New York Power Authority gives up to 2,600 MW for its whole Niagara project. The map also draws Sir Adam Beck 1 and 2 (450 and 1,499 MW) downstream of the falls.
Sources: NYPA, International Joint Commission, Wikipedia, Schoellkopf Power Station, Wikipedia, Adam Beck