The USGS Water Science School
In 2012, the Three Gorges Dam in China took over the #1 spot of the largest hydroelectric dam (in electricity production), replacing the Itaipú hydroelectric power plant in Brazil and Paraguay. The Three Gorges Dam has a generating capacity of 22,500 megawatts (MW) compared to 14,000 MW for the Itaipu Dam. But, over a year-long period, both dams can generate about the same amount of electricity because seasonal variations in water availability on the Yangtze River in China limit power generation at Three Gorges for a number of months during the year.
The height of Three Gorges is about 594 feet (181 meters (m)) and the length is about 7,770 feet (2, 335 m). The dam creates the Three Gorges Reservoir, which has a surface area of about 400 square miles (1,045 square kilometers) and extends upstream from the dam about 370 miles (600 kilometers).
In the United States, the Grand Coulee Dam on the Columbia River, Washington, is the largest, with a generating capacity of about 6,800 MW (5th overall worldwide).
Photo credit: Le Grand Portage, Wikipedia
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