Hoover Dam
Once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression, and was dedicated on September 30, 1935, by President Franklin Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley.
There were 112 deaths associated with the construction of the dam.[68] Included in that total was J. G. Tierney, a surveyor who drowned on December 20, 1922, while looking for an ideal spot for the dam. He is generally counted as the first man to die in the construction of Hoover Dam. His son, Patrick W. Tierney, was the last man to die working on the dam's construction, 13 years to the day later.[68] Ninety-six of the deaths occurred during construction at the site.
Of the 112 fatalities, 91 were Six Companies employees, three were BOR employees, and one was a visitor to the site, with the remainder employees of various contractors not part of Six Companies.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100 ft (30 m) long and 16 ft (4.9 m) high steel drum gates. Each gate weighs 5,000,000 pounds (2,300,000 kg) and can be operated manually or automatically. Gates are raised and lowered depending upon water levels in the reservoir and flood conditions. The gates cannot completely stop water from entering the spillways but help maintain an extra 16 ft (4.9 m) of lake level.
This is one of the greatest humanity structure, which curbed Colorado River.
Look at this Dam:
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