The Hoover dam was built during the Great Depression. Construction of the dam began in 1931 under the supervision of the Bureau of Reclamation. Six different companies were contracted to build the dam, which is named after President Herbert Hoover. Originally, the dam was to be built in Boulder Canyon as the project was named the Boulder Project. After additional surveying in the area, Black canyon was found to be a better spot to build the dam. Black Canyon was narrower and the bedrock under the Colorado River in Black Canyon was better suited to build a dam. Even though the location was changed, the project kept the same name and when the dam was completed it was originally known as Boulder Dam. The name was not officially changed to Hoover dam until 1947.
The main purpose for the dam was for flood control of the Colorado River. Before the dam was built there would be times when the river was very high and escaped its banks flooding agricultural pastures. Other times the river would be very low and there wasn’t enough water to distribute.
In order to build the dam, the Colorado River had to be diverted so diversion tunnels were built. Coffer dams were put in place and the river was re-directed to the tunnels through the mountain to the downside of the construction site. Another coffer dam was built downstream from the site to make sure the water would not back up to the construction site.
The General Superintend of the project was a man name Frank Crowe. He pushed the construction workers hard to complete the dam ahead of schedule and earned the name “Hurry up Crowe”. A group of men known as “Highscalers” had a very dangerous job; they rappelled up and down the canyon walls drilling holes to place dynamite. They would have to swing off to the side in hopes that their timing is correct as to avoid being blasted as the dynamite went off. To protect their heads from falling objects, the high scalers would take cloth hats and dip them in tar allowing them to harden up. This was the beginning of what is known today as hard hats.
The official death toll was 112 deaths. The first death tied to the project was a surveyor by the name of J.G. Tierney who drowned on December 20, 1922. The last death was his son, Patrick Tierney, who died thirteen years later to the day.
Spillways were constructed on either side of the dam. These were built so that water could be diverted around the dam and through the diversion tunnels. The diversion tunnels are 56 feet in diameter and lined in concrete three feet in thickness. The pouring of concrete ended on May 29, 1935 and was dedicated in September of the same year. A total of 3,250,000 cubic yards of concrete was poured in the project, which is enough concrete to pave a two lane road from San Francisco to New York City.
It took 6 years to fill the reservoir after the dam was completed. The reservoir is called Lake Mead, which is named after the first commissioner of the Bureau of Reclamation known as Dr. Elwood Meade. The diversion tunnels have only been used twice since the completion of the dam. The lake reached full capacity in 1941 and the water went over the spillway and through the diversion tunnels as a test run. The only other time the tunnels had water going through them was in 1983. When the dam was completed it was the tallest dam in the world and today is known to be one of the Engineering Marvels of the United States. Hoover dam opened for tours in 1937 and has become a very popular tourist destination since then.
Today, approximately a million people a year take a tour of Hoover Dam.