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Hydropower explained Where hydropower is generated

Most U.S. hydroelectricity generation capacity is in the West

Nearly all states have conventional hydroelectric facilities. Most hydroelectricity is produced at large dams built by the federal government, and many of the largest hydropower dams are in the western United States.

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About one-half of total U.S. utility-scale conventional hydroelectricity-generation capacity is concentrated in Washington, California, and Oregon.1 Washington has more conventional hydroelectricity-generation capacity than any other state and is the site of the Grand Coulee Dam, which is the largest U.S. hydropower facility and has the highest electricity-generation capacity of all U.S. power plants. East of the Mississippi River, New York has the highest conventional hydroelectricity-generation capacity, followed by Alabama.

In 2023, total U.S. conventional hydroelectricity net summer generation capacity was about 80,090 megawatts (MW)—or about 80 million kilowatts.

  • The top five states and their percentage shares of U.S. total conventional hydroelectricity net summer generation capacity in 2023 were:2
  • Washington27%
  • California13%
  • Oregon10%
  • New York6%
  • Alabama4%

Hydroelectricity generation varies with precipitation levels

Because hydroelectricity generation ultimately depends on precipitation, and precipitation levels vary seasonally and annually, the ranking of each state in terms of annual hydroelectricity generation may be different from its ranking in generation capacity.

In 2023, total U.S. conventional hydroelectricity generation was about 6% (about 240 billion kilowatthours [kWh]) of total U.S. utility-scale electricity generation.

  • The top five states and their percentage shares of total U.S. conventional hydroelectricity generation in 2023 were:3
  • Washington25%
  • California13%
  • New York12%
  • Oregon10%
  • Alabama4%

Pumped-storage hydro

In 2023, the United States had about 23,167 MW of total pumped-storage hydroelectricity generation capacity in 18 states. The top five states combined were 61% of the national total.

  • The top five states and their percentage shares of total U.S. pumped-storage hydroelectricity net summer generation capacity in 2023 were:4
  • California17%
  • Virginia14%
  • South Carolina13%
  • Michigan9%
  • Georgia8%

Most pumped-storage hydroelectricity systems use more electricity to pump water to upper water storage reservoirs than they produce with stored water. Therefore, most pumped-storage facilities have net negative annual electricity generation balances.

Most dams were not built for electricity generation

Only a small percentage of the dams in the United States produce electricity. Most dams were constructed for irrigation and flood control and do not have hydroelectricity generators. The U.S. Department of Energy estimated that in 2012, non-powered dams in the United States had 12,000 MW of potential hydropower capacity.

1 Utility-scale power plants have at least 1 MW (or 1,000 kilowatts) of total net electric generation capacity.
2 U.S. Energy Information Administration, Electric Power Monthly, February 2024, Table 6.2.B, preliminary data
3 U.S. Energy Information Administration, Electric Power Monthly, February 2024, Table 1.10.B, preliminary data
4 U.S. Energy Information Administration, Electric Power Monthly, February 2024, Table 6.2.A, preliminary data

Last updated: June 21, 2024.