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.
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.
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.
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.
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.