What Are the Parts of the Hoover Dam?

What Are the Parts of the Hoover Dam?
Hoover Dam, 30 miles southeast of Las Vegas, on the Colorado River, is a massive arch-gravity type dam constructed between 1931 and 1935. Built for flood control, water supply, irrigation and power, the 247 square-mile reservoir Lake Mead backs up behind the dam. The lake extends 110 miles upstream to the Grand Canyon. Hoover Dam also straddles the border between Arizona and Nevada.

Hoover Dam

Construction of the dam took 3.2 million cubic yards of concrete. The concrete was poured as 60-foot square interlocking blocks with 528 feet of 1 inch steel pipe running through the 215 concrete blocks. The dam is 660 feet wide at the base and 726 feet high.

Diversion Tunnels

Four diversion tunnels, two on each side of the dam, were built to divert the Colorado River around the dam construction. Totaling 3 miles long, today these tunnels are partially plugged and connect the intake towers in the reservoir to the Hoover Powerplant and to the canyon wall outlets.

Intake Towers

The four intake towers rise above the lake and dam. Made of reinforced concrete, the towers are 395 feet tall and 63 feet wide at the top. Attached to the top of the dam by walkways, there are two towers on each upstream side of the dam. Gates in the towers control the flow of water into the penstocks.


Thirty-foot wide steel pipes called penstocks direct water from the intake towers to the dam's power plant. The huge penstocks transport 90,000 gallons of water per second down to the power plant. The energy created by the water descending from the surface and passing through turbines located toward the bottom of the dam creates hydroelectric power.

Hoover Powerplant

Located in the U-shaped concrete structure at the base of the dam, the Hoover Powerplant produces electricity for Arizona (19 percent), Nevada (23 percent) and California (58 percent). According to the Bureau of Reclamation, this power plant produces an average of 4 billion kilowatt hours annually. This equals enough power for 1.3 million people each year. The concrete housing is 650 feet long and 299 feet tall.


Turbines, which are giant wheels with blades, are part of the power plant's 17 massive generators. Water moving through the turbines turns an attached shaft. Electromagnets are attached to the shaft and, in turn, these are surrounded by copper coils. As the shafts and magnets spin, this displaces electrons in the copper coils thus producing electricity. As the water flows past the turbines it is discharged back into the river.

Spillways and Outlets

Attached on either side of Hoover Dam near the top are spillways. More than 650 feet long and 170 feet wide and lined with concrete, the spillways function to divert water around the dam, especially when the lake level is high. Other outlet pipes divert water from the base of the penstocks away from the power plant.

Visitor Center

Along the top of the dam is a visitor center that offers exhibits, presentations, displays, tours, and information on the history and operation of Hoover Dam. Touring the power plant requires riding in an elevator 530 feet down into the depths of the dam.

Article Written By Damian Fagan

Damian Fagan is a writer living in the Pacific Northwest. He has written several field guides for the Globe Pequot Press and published articles in magazines such as "Bird Watchers Digest," "Moab Happenings," "Faces" and "Appleseeds." Fagan holds a Bachelor of Science in botany.

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