Water to the desert: the history of the Hoover Dam
Posted: May 05, 2025
Before the dam, there was nothing but the desert.
Well, that’s not entirely true. There were of course people and cities in the southwestern US before the arrival of the Hoover Dam, that monument to the control of nature that still looms larger in the collective imagination than most other modern infrastructure projects—even though it has long been surpassed in scale.
But the Hoover Dam, and the other massive developments it spawned, were instrumental in taming this arid region and supercharged the growth of cities from Los Angeles to Denver to Phoenix. As a lifelong resident of Las Vegas later recalled, prior to the dam’s arrival the city consisted of a single paved street—“everything else was dust.”[1]
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Why the Colorado River was dammed
For decades before plans for the dam were drawn up, the newly formed Bureau of Reclamation, then still known as the Reclamation Service, had been studying what it could do with the Colorado River.[2]
Early efforts to bring water to the Southwest had primarily focused on irrigation. But by the 1920s, a dam was seen to serve a triple purpose: in addition to opening up vast stretches of arid land for farming, it could also produce large amounts of hydropower and protect communities from flooding.
The dam’s engineers hoped to build on other water management schemes in the region. Not long before, an older irrigation canal bringing water from the Colorado River to the Imperial Valley had developed a years-long leak; by the time it was plugged, the escaping water had created the Salton Sea, a saline lake in southern California.
Lastly, the dam would open a critical supply of municipal water for greater Los Angeles. Although the city had already diverted the Owens River in 1913, it was still at risk of running out of water for its rapidly growing population: between 1920 and 1952, it would balloon from a community of just 500,000 to a major urban center of 2 million.
But to achieve all this, the planners and engineers involved faced a daunting task: raising a barrier higher than any that had ever been built, capable of impounding two years' worth of the river’s flow behind its concrete walls.
How the Hoover Dam was built
The place they originally chose for their monumental undertaking was Boulder Canyon. It would lend the dam its name until the 1950s even though the site was quickly moved to Black Canyon, 20 miles farther downstream. Both offered ideal conditions: dramatic, narrow gorges with steep walls rising from the riverbed for hundreds of feet.
For the dam, the Reclamation Service settled on a curved arch-gravity design, similar to concrete arch dams it had already built on the Boise and Salt Rivers. Its curved face keeps the dam from bursting under the staggering pressure of the 9 trillion gallons of water behind it by transmitting all that elemental force into the rock walls of the canyon instead.
While the overall structure was decided early, the dam’s now iconic Art Deco-inspired facade almost turned out very differently. The architectural designs were originally neo-classic, featuring eagles with wide-spread wings; only a last-minute redesign by Los Angeles architect Gordon Kaufmann settled its more modern look.
Before work on the actual dam could begin, workers had to drive tunnels through either side of the canyon’s hard rock to divert the Colorado away from the building site. Because such a large concrete structure had never been built before, the work also threw up unexpected challenges.
For example, the massive amount of concrete the workers were pouring would have generated so much heat when curing that it wouldn’t have cooled even down to this day—and would have eventually caused the dam to crack and crumble. So the builders incorporated steel pipes to run water through the structure as they went.
Meanwhile, excavating the canyon walls required workers, known as high scalers, to rappel from the top of the canyon by ropes and blast away loose rock with jackhammers and dynamite. The nature of that work goes some way to explain the toll it took: building the dam claimed the lives of around 100 of the 21,000 men who worked on it.
The legacy of the Hoover Dam
The project was so huge, it took a consortium of construction companies, aptly called Six Companies Inc., to carry it out. (This was not least due to the fact that securing the $5 million bond the government was demanding for the project was too risky for a single firm to bear.)
Given the size of the development, even the location of the dam-building headquarters inspired fierce competition. The city of Las Vegas lobbied hard for it, even closing all its speakeasies when Secretary of the Interior Ray Wilbur came to town to scout for a location. Instead, a model city was eventually raised closer to the canyon; today, it’s known as Boulder City, Nevada.
The dam itself was finished in 1936, just five years after construction started and, incredibly, two years ahead of schedule and under budget. It was the largest public works project the U.S. had ever undertaken to date.
According to Bechtel, one of the firms in the Six Companies consortium, the dam was “mankind’s most massive masonry structure” since the Great Pyramids were built more than 4,000 years earlier: stretching 1,244 feet across Black Canyon, it contained 4.4 million cubic yards of concrete and 45 million pounds of reinforced steel.[3]
To this day Lake Mead, its storage reservoir, is the largest man-made lake in the U.S.—enough, when full, to cover the whole state of Connecticut ten feet deep. Each of the dam’s spillways can accommodate the water flow of Niagara Falls.
Although building had started before the Great Depression, Hoover Dam also became a potent symbol of the New Deal’s roll-up-your-sleeves optimism, a monument to American resilience and ingenuity. In its wake, multipurpose dams were built across the country.
After their success on the project, parts of the consortium would go on to help build a host of other massive water projects, including Parker Dam and the Colorado River Aqueduct. It even laid the foundations for the Golden Gate and Bay bridges.
Today, although it has long been dwarfed by others, visitors still flock to Hoover Dam to look down its seemingly endless concrete curtain. As Franklin D. Roosevelt proclaimed when dedicating it: "I came, I saw, and I was conquered, as everyone will be who sees for the first time this great feat of mankind.”
