Most of U.S. hydroelectricity generation capacity and electricity generation is in the West

Every U.S. state has hydropower/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.

About half of U.S. hydroelectricity generation capacity1 is concentrated in Washington, California, and Oregon. Washington has the most hydroelectric generating capacity of any state and is the site of the Grand Coulee Dam, the largest hydropower facility in the United States. New York has the largest hydroelectricity generation capacity of all states east of the Mississippi River, followed by Alabama.

In 2017, total U.S. hydroelectricity generation capacity was about 80,058 megawatts (MW)—or 80 million kilowatts. The top five states and their share of U.S. total hydroelectricity generation capacity in 2017 were

  • Washington—27%
  • California—13%
  • Oregon—11%
  • New York—6%
  • Alabama—4%

Because the amount of electricity generation from hydropower depends on precipitation, the ranking of each state in annual hydroelectricity generation may be different from its ranking in generation capacity.

In 2017, total U.S. hydroelectricity generation was about 300 billion kilowatthours (kWh), equal to about 7.5% of total U.S. utility-scale electricity generation. The top five states and their share of U.S. total hydroelectricity generation in 2017 were

  • Washington—28%
  • Oregon—14%
  • California—12%
  • New York—10%
  • Montana—4%

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 (DOE) estimated that in 2012, non-powered dams in the United States had a total of 12,000 megawatts (MW) of potential hydropower capacity.

1Net summer capacity for utility-scale conventional hydroelectric power; does not include pumped storage hydropower.