Name: Hoover Dam
Address: United States
Telephone: (702) 494-2517
Rating: 4.7

Depression-era engineering marvel offering tours & scenic views of the Colorado River & Lake Mead.

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The Hoover Dam is located in the Black Canyon of the Colorado River, on the border between Nevada and Arizona.

Location

Construction of the Hoover Dam took place during the Great Depression in the 1930s, providing jobs for thousands of workers.

Construction Era

The amount of concrete used to build the Hoover Dam was enough to pave a two-lane highway from San Francisco to New York City.

Material Quantity

The dam created Lake Mead, which is one of the largest artificial reservoirs in the United States.

Artificial Lake

To build the dam, the Colorado River was diverted through four tunnels, each 56 feet in diameter, dug through the canyon walls. The river essentially had to make a U-turn.

River Diversion

During the construction of the Hoover Dam, approximately 96 workers died from accidents and illnesses.

Worker Deaths

The Hoover Dam features a striking Art Deco design, with sculptures and motifs incorporated into its structure.

Architectural Style

The Hoover Dam's power plant can generate approximately 4 billion kilowatt-hours of electricity each year, enough to serve millions of homes.

Electricity Production

Hoover Dam

Hoover Dam, a concrete arch-gravity dam in the Black Canyon of the Colorado River, uniquely straddles the border between Nevada and Arizona. Its construction, completed in 1936, was a monumental feat of engineering, requiring the diversion of the entire Colorado River through four massive tunnels bored through the canyon walls. The dam's design incorporates a distinctive Art Deco style, evident in its intake towers and sculpted ornamentation, a deliberate choice to elevate its utilitarian purpose. A lesser-known aspect is the dam's impact on the Colorado River's ecosystem, drastically altering downstream water temperature and sediment flow, which in turn affected native fish populations and riparian habitats. The sheer volume of concrete used was so immense that the initial design required a cooling system of embedded pipes to prevent cracking during the curing process, a system that remains in place today. The dam's power plant generates electricity for millions, a testament to its enduring contribution to the region's energy infrastructure.

Introduction

Hoover Dam, a National Historic Landmark, exemplifies Art Deco design integrated into infrastructure. Completed in 1936, its design incorporates geometric forms and ornamental details, though many are concealed within the structure. Architect Gordon B. Kaufmann, known for his work on the Los Angeles Times Building, streamlined the dam's design with Modernism and Art Deco influences, particularly visible in the power plant, dam crest, spillway, and intake towers. The intake towers feature bas-relief panels, with the Nevada elevator tower depicting the dam's benefits: flood control, navigation, irrigation, water storage, and power.

The dam's Art Deco elements offered a hopeful vision during the Great Depression, suggesting technology could overcome economic challenges. Oskar Hansen’s bas-reliefs in the inner circulation zones illustrate the dam's functions, emphasizing engineering's triumph over nature and referencing local Indigenous history. Kaufmann aimed for plain surfaces with strategic shadows rather than overt architectural styling. His simplified designs influenced subsequent dams like Parker and Shasta. The four intake towers showcase dominant vertical lines, reminiscent of abstracted Gothic Revival skyscrapers. These artistic details narrate the dam's significance to American society during a difficult period, blending functionality with aesthetic appeal.

Art Deco Architectural Design

Authorized under President Herbert Hoover and completed during Franklin D. Roosevelt's administration, the Hoover Dam became a potent symbol of Great Depression-era public works projects aimed at revitalizing the American economy and providing employment. As the Depression deepened, the dam project offered a beacon of hope, attracting thousands of laborers to Las Vegas seeking work. The construction of the dam was authorized under Hoover’s presidency, it became a symbol of President Franklin Roosevelt’s public works projects.

The project commenced in 1931, amidst widespread unemployment, and was completed in 1935, two years ahead of schedule. Despite the economic hardships, workers faced dangerous conditions, including extreme heat, carbon monoxide exposure, and the risk of falls. A strike in August 1931 highlighted the unsafe working conditions, yet sufficient labor remained, leading to the creation of Boulder City to house the workforce.

The Hoover Dam project exemplified the New Deal's approach to public works, putting Americans back to work during a time of immense economic hardship. Its construction not only provided jobs but also captured the imagination of the nation, symbolizing a brighter future amid the despair of the Depression. The dam's early completion further solidified its image as a triumph of American ingenuity and a testament to the power of public works in overcoming economic challenges.

Great Depression Public Works

Hoover Dam's hydroelectric power generation capacity stems from its unique design and operational features. Water from Lake Mead enters intake towers before flowing through penstocks, reaching speeds of 85 mph and providing a maximum hydraulic head of 590 feet to drive the turbines. The entire flow of the Colorado River typically passes through these turbines, with spillways and outlet works reserved for emergencies or maintenance.

From 1986 to 1993, an uprating project boosted the plant's gross power rating to a maximum capacity of 2080 megawatts, including two 2.4-megawatt Pelton turbine-generators powering the dam's operations. The plant houses 17 main turbines, with the original turbines replaced during the uprating program. These turbines operate under varying heads, averaging 510 to 530 feet.

The dam's power generation has been self-sustaining, with proceeds from electricity sales repaying the construction loan and funding annual maintenance. Power generation is synchronized with downstream water demands. The average annual net generation from 1947 to 2008 was 4.2 billion kilowatt-hours, peaking at 10.348 TWh in 1984. However, prolonged drought and high water demand have decreased electricity generation, leading to a downrating of capacity to 1592 MW by 2014. To address falling water levels, five wide-head turbines were installed to maintain power generation at lower water levels. The Bureau of Reclamation operates and maintains the powerplant, distributing energy to various contractors across Arizona, Nevada, and California.

Hydroelectric Power Generation

Hoover Dam exemplifies arch-gravity dam engineering, combining the characteristics of both arch and gravity dams to resist water pressure through its weight and arch action. The dam transfers horizontal forces into vertical forces along the abutments, counteracting overturning or sliding. Its design, supervised by John Lucian Savage, required the construction of four diversion tunnels and two cofferdams to manage the Colorado River's flow. These tunnels, created using dynamite, diverted the river, enabling work on the dam's foundation.

The dam's structure comprises an estimated 215 vertical columns, interlocked block by block with keyways, resembling a Lego set. Engineers addressed the challenge of concrete's heat generation during hardening by embedding 590 miles of pipe loops for circulating air-cooled water. The side-walls of the canyon bear the force of the impounded lake, necessitating excavation to reach virgin rock, preventing water seepage.

The large spillway tunnels, used sparingly, experienced damage due to cavitation, leading to repairs with heavy-duty concrete and the addition of flip buckets and aerators to mitigate future damage. The outer diversion tunnels were sealed with concrete plugs, repurposing the downstream halves as spillway tunnels. Inner diversion tunnels now contain steel pipes connecting intake towers to the power plant.

Arch-Gravity Dam Engineering

The construction of Hoover Dam in 1936 marked a turning point for the Colorado River Delta ecosystem. By dramatically altering the river's natural flow, the dam initiated a cascade of ecological consequences that continue to resonate today. Hoover Dam, followed by the construction of Glen Canyon Dam, blocked the crucial sediment flow necessary for maintaining riparian habitats downstream. This sediment deprivation led to the loss of riparian forests, which once provided essential support for diverse bird populations and other wildlife. The altered river flow and habitat degradation pushed four native fish species—humpback chub, bonytail chub, Colorado pikeminnow, and razorback sucker—to the brink of extinction.

The dam's impact extended far beyond the immediate vicinity of the river, decimating approximately 1.5 million acres of wetlands in the Colorado River Delta in Mexico. For a significant portion of the last 50 years, the river has been unable to reach the sea, resulting in the desiccation of the landscape and the disappearance of countless wildlife species. The construction of the Hoover Dam sapped the Delta of its freshwater, sparking its decline. Prior to the dam's construction, the Colorado River Delta thrived with riparian forests of cottonwoods, willows, and mesquite, as well as marsh and estuarine wetlands, covering around 2 million acres.

Hoover Dam

Did You Know?

Location

Construction Era

Material Quantity

Artificial Lake

Location