HOOVER DAM

HOOVER DAM. Located in the Black Canyon on the Colorado River, Hoover Damlies about thirty miles southeast of Las Vegas, Nevada. The federal government built it for flood control, navigation, irrigation, water storage, and power generation. Farmers in the region experienced disastrous Colorado River floods before the dam was constructed.

Herbert Hoover first proposed a dam for the Colorado River when he became secretary of commerce in 1921. At the time his plan involved a dam in Boulder Canyon. After he became president, Hoover proposed an "upper" and a "lower" basin, a compromise that made a dam possible by dividing the water among the states affected

by the river and its tributaries. Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming entered the Colorado River Compact in 1922, and in 1928 Congress authorized the construction of Boulder Dam, which later became the Hoover Dam.

During the Great Depression the government contractor, Six Companies, six formerly independent companies that had merged to get the job, constructed the dam, the highest concrete arch dam in the United States. Lake Mead, the reservoir the dam impounds, is one of the largest human-made lakes in the world, with an area of 247 square miles. The dam itself is 726.4 feet from the foundation rock on the roadway to the crest, with towers and ornaments extending another 40 feet above the crest. It weighs more than 6.6 million tons. With 17 turbines, the power facility has a nameplate capacity of 2.074 million kilowatts.

Of the thousands of people who worked on the dam between 1930 and 1936, ninety-six workers died from accidents directly relating to the building of the dam and dozens more from related ailments. Before the dam could even be started, Boulder City had to be built to house the workers, and miles of highways and railroads from the dam site to Boulder City and from there to Las Vegas had to be constructed. In the first step of building the dam, men attached to ropes were hoisted over the edge of the canyon, where they scraped loose rock from the canyon walls by hand. Four tunnels diverted the flow of the river, and a ton of dynamite was required to dig fourteen feet. The dam itself was made up of columns filled slowly with concrete. To cool the chemical heat released by the concrete, ice water ran through the equivalent of 582 miles of one-inch diameter pipes embedded in the concrete. After the columns were filled and cooled, grout was poured between them to make the structure monolithic.

The Hoover Dam was seen as a triumph of humans over nature. It was the first human-made structure to exceed the masonry mass of the Great Pyramid of Giza. By the twenty-first century the dam was regarded ambivalently, sustaining environmentalists' criticism that it in fact damaged or destroyed an ecosystem.

BIBLIOGRAPHY

Carothers, Steven W., and Bryan T. Brown. The Colorado River through Grand Canyon: Natural History and Human Change. Tucson: University of Arizona Press, 1991.

Dunar, Andrew J., and Dennis McBride. Building Hoover Dam: An Oral History of the Great Depression. New York: Twayne, 1993.

Stevens, Joseph E. Hoover Dam: An American Adventure. Norman: University of Oklahoma Press, 1988.

RuthKaplan

See alsoConservation ; Hydroelectric Power .