Hoover Dam
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Official name: Hoover Dam
Location: Clark County, Nevada / Mohave County, Arizona, U.S.
Purpose: Power, flood control, water storage, regulation, recreation
Status: In use
Construction began: 1931
Opening date: 1936
Construction cost: $49 million ($836 million with inflation)
Owner: United States Government
Operator: U.S. Bureau of Reclamation

Dam and spillways
Type of dam: Concrete gravity arch
Impounds: Colorado River
Height: 726.4 feet (221.4 m)
Length: 1,244 feet (379 m)
Elevation at crest: 1,232 feet (376 m)
Width (crest): 45 feet (14 m)
Width (base): 660 feet (200 m)
Dam volume: 3,250,000 cu yd (2,480,000 m3)
Spillway type: 2 controlled drum gate
Spillway capacity: 400,000 cu feet/s (11,000 m3/s)

Reservoir
Creates: Lake Mead
Total capacity: 28,537,000 acre - ft (35.200 km3)
Active capacity: 15,853,000 acre - ft (19.554 km3)
Inactive capacity: 10,024,000 acre - ft (12.364 km3)
Catchment area: 167,800 sq mi (435,000 km2)
Surface area: 247 sq mi (640 km2)
Max. length: 112 mi (180 km)
Max. water depth: 590 feet (180 m)
Normal elevation: 1,219 feet (372 m)

Power station
Operator: U.S. Bureau of Reclamation
Commission date: 1936 - 1961
Hydraulic head: 590 ft (180 m) (Max)
Turbines: 13x 130 MW, 2x 127 MW, 1x 68.5 MW, 1x 61.5 MW Francis-type, 2x 2.4 MW Pelton-type
Installed capacity: 2,080 MW
Annual generation: 4.2 billion kWh
Bureau of Reclamation: Lower Colorado Region - Hoover Dam
U.S. National Register of Historic Places
U.S. National Historic Landmark

Nearest city: Boulder City, Nevada
Built: 1933
Architect: Six Companies, Inc. (structural), Gordon Kaufmann (exteriors)
Architectural style: Art Deco
MPS: Vehicular Bridges in Arizona MPS (AD)
NRHP: Reference #81000382

Significant dates
Added to NRHP: April 8, 1981
Designated NHL: August 20, 1985

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 U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. The dam was controversially named after President Herbert Hoover.

Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc., which began construction on the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on March 1, 1936, more than two years ahead of schedule.

Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily travelled U.S. 93 ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.