Sept. 30, 1936: Civil Engineering Marvel Dedicated
By Ellie Boese treditor@times-online.com
On September 30, 1936, tens of thousands of Americans gathered at the Nevada-Arizona border, where President Franklin D. Roosevelt was dedicating the concrete marvel that had tamed the Colorado River.
At the turn of the century, farmers attempted to divert the rushing Colorado River toward the many blooming southwest communities with a series of canals. The river refused to be tamed, breaking through the constructed channels in 1905, so the US Bureau of Reclamation was tasked with controlling the waters.
In 1922, Congress heard of plans for a multi-purpose dam in Black Canyon, one that could control flooding and irrigation while generating hydroelectric power and supplying surrounding areas water.
At first, lawmakers were concerned with the project’s price tag and representatives from the states in the river drainage area were worried the water resources would be funneled to California communities.
It was US Secretary of Commerce Herbert Hoover who worked to develop a compromise and secured the necessary agreements to move the dam’s construction forward. He became president in 1929, and the project was named in honor of him.
Even before construction began in 1933, people desperate for employment in a country in the grip of the Great Depression flocked to the area. There, they set up camps, in hopes they could find work on the project. Individuals who were hired were eventually moved to Boulder City, which had been created to house Hoover Dam workers.
Building a Modern Marvel
Construction began with workers blasting canyon walls, carving out tunnels that would divert the Colorado River. Four tunnels, each 56-feet in diameter, were bored through the cliffs. After the river was relegated to its new paths, workers moved on to another treacherous task: clearing the canyon walls that would anchor the dam. They dangled 800 feet in the air, using jackhammers and metal poles to jar the rock loose.
As their comrades worked hundreds of feet above them, laborers on the canyon floor began constructing the dam, power plant and intake towers.
Concrete was mixed on site and placed in blocked sections. As the huge blocks were poured, Architect Gordon Kaufmann’s vision for the project came into view. He’d chosen a somewhat monumental, futuristic design, keeping the massive curved face of the dam smooth and free of added features.
Around 21,000 workers contributed to its construction, utilizing 6.6 million tons of concrete and 22,500 pounds of reinforced steel to erect a modern marvel. The $49 million spent on the project wasn’t the only cost the nation found accompanied such a historic endeavor; 96 laborers lost their lives during construction.
At the time of its completion in 1935, the Hoover Dam was the largest dam on earth. If we took the structure’s 6.6 million
tons of concrete and used them to lay a paved road, it would stretch from San Francisco to New York City.
Thousands of people gathered at the Hoover Dam on September 30, 1935, to watch President Franklin D. Roosevelt dedicate the completed structure. It was an engineering marvel that tamed the Colorado River, distributing its waters throughout the dry southwest United States, allowing for the explosive growth of major cities like Los Angeles, Las Vegas and Phoenix.
Energy by Water & Gravity
The dam started generating electrical power immediately upon completion. Thanks to its extreme height, the main forces of energy creation are completely natural: water and gravity. Four intake towers sit in Lake Mead, just above the dam. Water taken into them from the reservoir is diverted into steel pipes, falling some 500 feet to the base of the dam. There, the gravity-powered, fast-moving waters turn 17 turbines that rotate a series of electric generators. With gravity, water, turbines and generators, the Hoover Dam produces more than 4 billion kilowatt-hours annually. That massive hydroelectric capacity provides energy to an estimated 18 million people in Nevada, California and Arizona.
Man-Made & Natural Wonders
The Hoover Dam was designated a National Historic Landmark in 1985 and dubbed one of America’s 7 Modern Civil Engineering Wonders in 1994. It attracts more than 7 million visitors each year. Visitors can stand atop the concrete arch and look over its southern edge and see the Colorado River 760 feet below or peer at Lake Mead’s waters to the north. Tourists also have a chance to take a peek at the dam’s inner workings, seeing historic tunnels, hydroelectric equipment and the power plant.
The Hoover Dam, though man-made and standing in stark contrast to the surrounding wilderness, has created a budding natural oasis: Lake Mead, designated as America’s first National Recreation Area. It boasts 1.5 million acres of mountains, valleys, canyons and two lakes—Lake Mead and Lake Mohave—along with various wilderness areas. More than 10 million outdoor enthusiasts enjoy boating, swimming, hiking, camping and fishing every year in the area.
Protecting Hoover Dam
The Hoover Dam, as a civil engineering wonder, has faced a number of security threats on an international scale. Its importance in the US has made it a wartime target.
Shortly after the start of World War II, the US Embassy in Mexico City got word of a plot by German agents in that area to bomb the intake towers at Hoover Dam. It was rumored that the US aviation industry was aiding Great Britain, so the plot was allegedly hatched to cripple the power source for the aviation manufacturing industry in Los Angeles: the Hoover Dam.
US federal officials responded by increasing security. Officials installed floodlights and checkpoints, and strung a wire net across Lake Mead that would keep boats from getting within 300 feet of the intake towers.
Because of the dam’s hydroelectric capacity, it became a major power source for the manufacture of airplanes, tanks, guns, warships and other equipment vital to the war effort.
In 1941, the Secretary of Interior created a system that classified certain structures by their importance to the US. Hoover Dam fell under Class I: “of paramount importance to and irreplaceable in operations of national defense by reason of major power supply.” Around that same time, the US was constructing a magnesium processing facility in southern Nevada. Magnesium ore was one of the most common materials in aircraft production, and could also be used for munitions.
The BMI Plant’s largescale operations were powered by the nearby Hoover Dam, making the concrete structure an even more valuable asset to the US.
Armed guards were situated at every vulnerable feature on the dam from that point forward.
At one point, US authorities toyed with the idea of employing decoy/ camouflage techniques to protect the Hoover Dam. One idea, in 1943, was to put up a “dummy dam” upstream from the actual dam. The decoy, which would appear to be a concrete dam when viewed aerially, would be created by stringing cables across the lake and draping wire mesh over them. Though the top-secret project yielded illustrated designs of such plans, no decoys of this sort were deployed at the Hoover Dam.
Though World War II’s end brought security levels down, security controls like checkpoints and a command center were implemented in direct response to the attacks on September 11, 2001. In 2005, a highway bypass was completed after four years of construction, diverting the high volume of traffic traveling atop the
Hoover Dam. Now personnel can focus on the many wide-eyed visitors while passing traffic whizzes easily by.