The Hoover Dam, also sometimes known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Arizona and Nevada. When completed in 1935, it was both the world's largest electric-power generating station and the world's largest concrete structure.
Construction began in 1931 and was completed in 1935, more than two years ahead of schedule.
To divert the river's flow around the construction site, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 feet in diameter, reduced to 50' following the application of 3' of concrete. Their combined length was nearly 16,000 feet (4877 meters, more than three miles).
Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt generators that power the plant's operations, is about 2080 megawatts. Electricity for the complex itself is provided by a single pelton wheel generator.