Hoover Dam

What is the biggest dam in the world?

When Hoover Dam was finished in 1935 it was the tallest dam in the world. From about 1938 until 1948 the Hoover Dam power plant was the largest hydroelectric producer in the world. Since then, bigger but not necessarily better facilities have been built, and people often ask us what is the biggest dam in the world today? The answer depends on what you mean by biggest. Do you mean the tallest dam? Or do you mean the one with the most material in it? Or, how about the biggest hydroelectric producer? The answer to each of these questions is a different dam.

World's Largest Dam by Volume

Syncrude Tailings Dam in Canada is currently ranked number one by volume of construction material at 706,320,000 cubic yards (540,000,000 cubic meters). These are mine tailings so the more they mine and add to the tailings the larger the structure will grow. In contrast, Hoover Dam contains 3,250,000 cubic yards (2,600,000 cubic meters) of concrete, which is much less. Hoover Dam is solid concrete and it was designed specifically to be used as a dam, whereas, the Syncrude Tailings is the piled up dirt left over from mining operations. Although the material is compacted and otherwise treated to make a stable structure it relies on volume of material to hold water back. Hoover Dam relies not only on volume of material but the strength of that material.

World's Tallest Dam

The tallest dam in the world is currently located on the Vakhsh River in Tajikistan and is called Rogun. It is 1099 feet (335 meters) tall. Hoover Dam is 726.4 feet (221.3 meters) tall. Today Hoover Dam ranks number 20 or 21 on the list of tallest dams. The uncertainty is due to the Tehri Dam in India. It is still under construction, but when it is finished it will be the about 856 feet (261 meters) tall. There is one dam in the United States taller than Hoover Dam, and that is the Oroville Dam on the Feather River in California. It stands 770 feet (235 meters) tall, but it is not a solid concrete dam like Hoover. In fact Hoover Dam is still the tallest solid concrete dam in the western hemisphere.

World's Largest Hydroelectric Plants

The Itaipu Dam on the border between Brazil and Paraguay can produce 12,600 megawatts (MW). The largest hydroelectric plant in the United States is the Grand Coulee Dam. Its three power plants can produce a total of 6,809 MW. The Hoover Dam power plant weighs in at 2,074 MW, which is still a lot of electricity. As a comparison, the Diablo One nuclear plant in California makes about 1106 MW, so Hoover Dam is the equivalent of two nuclear power plants (generally speaking).

Hoover Dam is no longer the biggest in any of these categories, but it does remain among the biggest.

Information in this article was compiled from the following sources:

Bureau of Reclamation
U.S. Society on Dams
Itaipu Dam Web Site at https://www.itaipu.gov.br
International Water Power and Dam Construction
U.S. Nuclear Regulatory Commission