The USA. A Virtual Tour

During snowmelt in the Rocky Mountains, the raging Colorado River often flooded farmlands. At the same time, nearby California was suffering from water shortages. The creators of the dam hoped that its construction would help smooth out fluctuations in the level of the river and boost development of Southern California.

On November 24, 1922, a commission of representatives from several states and Secretary of Commerce Herbert Hoover signed the «Hoover Compromise», which fixed the division of water resources. The signing of this document opened the way for the construction of the dam.

The construction of such a large-scale structure required the attraction of significant funds. Only in 1928 did President Coolidge approve the project. Money for the construction was allocated only in July 1930, when Herbert Hoover became president.

The construction of the dam was planned in a canyon between Nevada and Arizona. It involved several thousand workers under the leadership of «Six Companies, Inc.». According to the terms of the contract, the employment of the Chinese was not allowed; blacks were allowed only three dozen as laborers. Construction began in May 1931. To divert the Colorado River from the construction site, four tunnels with a diameter of 17.1 m were drilled in the Black Canyon rock. The total length of the tunnels is 4.9 km. The tunnels were covered with concrete, as a result, the diameter was 15.2 m. After the construction was completed, the tunnels were partially blocked and are now used to supply and discharge water.

To isolate the construction site and prevent possible flooding by the waters of the river, two small dams were built. In order to ensure the safety of work, before starting construction, lying stones and some rocks were rubbed into dust with dynamite.

It was planned that an entire city would be built for the builders – Boulder City, but the construction schedule was adjusted in favor of accelerating and increasing the number of jobs (against the backdrop of the Great Depression). The dam builders spent the first summer in temporary camps. This led to a strike on August 8, 1931. The uprising was broken up, but the temp of construction in Boulder City increased, and by the spring of 1932, workers had moved into permanent housing. Boulder City banned the sale of liquor (until 1969) and gambling (still today). In the rest of the cities of Nevada, gambling was decriminalized («Assembly Bill 98», 1931) exactly to increase construction income, which led to the incredible growth of the city of Las Vegas. The construction of the dam was carried out in difficult conditions. Part of the work was carried out in tunnels where workers suffered from carbon monoxide. At the same time, the construction of the Hoover Dam was the first construction site to use safety helmets. A total of 96 people died during construction, including Mr. Tierney, who drowned in Colorado waters in December 1922 while looking for a site to build.

The first concrete was poured into the foundation of the dam on June 6, 1933. For the production of concrete, local deposits were discovered and concrete plants were built. The construction of the dam was completed in 1936, two years ahead of schedule. For the project, the architect Gordon Kaufmann was invited, who completed the exterior of the buildings in the Art Deco style. There are clocks on the spillway towers, one of which shows Mountain Time (Arizona, UTC -7), and the other - Standard Pacific Time (Nevada, UTC -8). Some technical solutions used in the construction process were of a unique nature. One of the problems was the cooling of concrete, heated during formation. The dam was built as a series of trapezoidal columns to allow heat to dissipate. Engineers have calculated that if the dam were built as a monolith, it would take 125 years for the concrete to cool completely (until the 2050s!). In addition, to speed up the cooling process, each new layer of concrete contained a cooling system of pipes into which river water flowed. In total, 600,000 tons of cement and 3,440,000 m³ of aggregate were mixed into concrete for the construction of the dam body. The Hoover Dam at the time of its completion was the most massive man-made structure on earth, exceeding the mass of the Pyramids of Giza. The used concrete would have been enough to build a road from San Francisco to New York.

The first electricity was generated on October 26, 1936. On September 12, 1939, the power plant reached a capacity of 705 MW - and became the most powerful hydroelectric power station in the world. To date, electricity at the station is generated by 17 generators with a capacity of up to 2070 MW. The power plant plays a critical role in the energy consumption of the Western United States. Load adjustments to generators are controlled by a station in Phoenix, Arizona (500 km from Hoover Dam) and are performed every 2 seconds. Until 1991, manual control was used, then – automated. In 1981, the dam was listed on the US National Register of Historic Places.

About name

The plan called for the construction of the Mead Dam and Reservoir in Boulder Canyon. As a result, the construction took place in the Black Canyon, but the name "Boulder" was preserved. At the official opening ceremony, Department of the Interior Secretary Ray Wilbur announced that the dam would be named Hoover in honor of the president, continuing the tradition of naming the largest dams after presidents in power at the time of construction (like Wilson Dam or Coolidge Dam). On February 14, 1931, the US Congress approved the official name of the Hoover Dam. In 1932, Hoover lost the election to Franklin Delano Roosevelt. Immediately after the new president took office, the administration initiated the renaming of the dam to "Boulder Dam". No official decision was made on this matter, but Hoover's name disappeared from all official documents and guidebooks. After Roosevelt's death, Congressman Jack Anderson presented a draft decision to return the Hoover Dam, and since April 30, 1947, it bears its modern name.

The height of the dam is 221.4 m, the length is 379.2 m, the width is 200 m at the base, 15 m at the top. The electricity generated by the station is distributed in the following ratio: Arizona - 18.95%, Nevada - 25.14%, Los Angeles - 15.42%, California - 40.49%. The construction of the Hoover Dam and the formation of the Mead Reservoir had a significant impact on the Colorado River. To this day, a trace of the maximum water (1983) is visible on the ground around the Mead. The construction of the Hoover Dam stopped the floods, endangering a number of species that have adapted to them. The construction of the dam markedly reduced the fish population. Four typical Colorado fish species are currently listed as endangered.