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Sunday, July 08, 2007

The Hoover Dam Begins, July 7, 1930

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Today in 1930, money was for appropriated by the United States Congress to build Hoover Dam, a concrete gravity-arch dam which straddles the border of Arizona and Nevada 30 miles southeast of Las Vegas, Nevada. It impounds Lake Mead, the largest reservoir in the United States. While not the largest dam in the United States today, it remains a powerful symbol of the ability, ingenuity and work ethic of thousands of men during the worst economic crisis the modern world has ever seen.

The Colorado River begins its run high in the Rocky Mountains, over 9,000 feet above sea level. It flows for 1,450 miles in a south-westerly direction towards the Gulf of California, although use of the river for irrigation means that most of the time there is nothing left to flow into the ocean. The river draws water from not only the Rockies, but from other parts of Colorado, Wyoming, Utah, New Mexico, Nevada, Arizona and California; all told, the river's watershed is a quarter-million miles in area.

When Americans of European ancestry first settled near the Colorado River in the 19th century, the waterway was seen as a mixed blessing. On one hand, it provided life-giving water for towns and farms along its length. But when heavy winters produced torrents of springtime runoff water, the river became a violent life-taker, capable of destroying anything in its path. This boom and bust cycle of life continued until the early 20th century, when the population of southern California and surrounding areas began to steadily increase. This put greater demands on water resources in the desert-like area. As farming became a larger industry, it became obvious that the Colorado River would have to be tamed and her resources better divided among those who lived in and near her basin.

In January, 1922, Secretary of Commerce Herbert Hoover met with the governors of the states through which the Colorado flowed. That November, they signed the Colorado River Compact, which spilt the river into upper and lower halves. The states in each region would decided how the water would be divided. This agreement paved the way for the construction of Hoover Dam and several others over the course of the Colorado River intended to help control flooding and allow irrigation and electricity generation. However, it was not until six years later that President Calvin Coolidge signed the bill that approved the Boulder Canyon Project. By the time money was actually appropriated in July, 1930, Herbert Hoover, the man behind the Colorado River Compact, was President.

As with most grand plans, the Boulder Canyon Project underwent changes during its implementation. The first change was probably the most dramatic: instead of building the dam in Boulder Canyon, it was decided to build instead in Black Canyon. But since the project was already well underway, it was decided to keep the Boulder Canyon name. The construction contract was award to Six Companies, Inc., a joint venture made up of six of the largest construction firms in the nation at that time. Among the company's owners was Henry J. Kaiser, the man whose company would later become famous for building Liberty ships during the Second World War. Frank Crowe, who became chief engineer of the dam project, was chosen to be the superintendent of Six Companies, Inc. Crowe had pioneered two practices that were crucial for building large concrete dams. First was a pneumatic system that would transport concrete over long distances; the second was an overhead cable system that would allow concrete to be pumped to any point at a construction site. Without these two innovations, it is doubtful that the dam could've been built.

The first step in building the dam was removing the loose rock from the walls of Black Canyon. Workers were suspended from the tops of the canyon walls by ropes and removed the loose rock using jackhammers and dynamite. As you can imagine, this was incredibly dangerous work. The next step was to isolate the building site from the Colorado River. This was done by first diverting the water into a set of four tunnels built into the sides of the canyon. Then, an upper and lower cofferdam were built at the construction site, allowing the area to be pumped free of water. This work was completed in the fall of 1932.

The first concrete pouring for the dam took place on June 6, 1933. While the act of pouring concrete for small projects is a fairly simple affair, pouring it for something as large as Hoover Dam took an enormous amount of planning and innovation. Concrete releases heat and contracts as it cures, two actions that would cause something as large as a dam to crumble and eventually collapse. To keep this from happening, thin steel pipes were installed in each form, through which chilled water flowed to dissipate heat; a refrigeration plant was built on the lower cofferdam for this purpose. These tubes were later filled with grout and left as part of the structure of the dam. There is an urban myth which states that some of the workers died from falling into the concrete of the dam while it was being poured; this is not true. The concrete was poured only six inches at a time, too shallow to kill anyone who fell into it.

More than 21,000 men worked on Hoover Dam. They came from all over the nation, from all walks of life. Since the dam was built during the worst years of the Great Depression, some of the workers took dangerous jobs only because they paid well and would relieve some of the financial stress on their families. 114 men died either working on the dam construction itself or during the work leading up to its construction. Boulder City, the nearest town to the dam, was built from scratch to house the workers and their families. Today, it is home to 15,000 people.

Hoover Dam was completed in 1935, two years ahead of schedule and millions of dollars below budget. It officially opened on March 1, 1936 at a cost of $49 million in 1936 dollars, a sum that would be more than $675 million today. It is 726.4 feet high, the highest dam in the nation at the time of its completion. It is 1244 feet wide and 660 feet wide at the base. Over 4.36 million square yards of concrete were used in it construction. Its hydroelectric plant, which uses the entire flow of the Colorado River except during times of flood, produces nearly 2,100 megawatts.

There was some controversy as to the naming of the dam. It was announced in September, 1930 that the new Boulder Dam would be named after President Hoover; it was a long-standing tradition that important dams in the United States were named after the President who was in office when they were constructed. However, Harold Ickes, President Franklin Roosevelt's Secretary of the Interior, had Hoover's name removed from any official documents mentioning the dam in 1933. This name change was not official, but the name Boulder Dam entered into the public vocabulary for the foreseeable future. It was not until 1947, during the Presidency of Harry Truman, that Hoover's name was once again added.

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