Note: Ballotpedia will be read-only from 9pm CST on February 25-March 2 while Judgepedia is merged into Ballotpedia.
For status updates, visit

Hydroelectric energy

From Ballotpedia
Jump to: navigation, search
Policypedia energy logo.PNG
State energy policy

State fracking policy

Energy policy terms

Fracking in the U.S.

Energy use in the U.S.

Energy policy in the U.S.

State environmental policy

Energy and Environmental News

Horizontal-Policypedia logo-color.png
Hydroelectric energy, or hydropower, is a renewable energy resource that uses the flow of water to generate electric energy.[1]


According to the U.S. Geological Survey, roughly 7 percent of the total power in the United States is produced by hydroelectric power plants.

Hydropower is a renewable energy resource because it primarily relies upon the natural water cycle of the earth to generate electricity. Hydroelectric power plants produce electricity by forcing water that is already flowing downstream through a hydraulic turbine, which is connected to a generator. The power is produced as water from dams spin the turbine blades that are connected to generators. The water then leaves the turbine and returns to a stream or riverbed. The electricity generated from this turning is then transferred to homes and businesses.[2]

Hydropower requires precipitation. High precipitation levels and large elevation changes make hydropower generation more feasible. Thus, mountainous areas, like in the Pacific Northwest, are more productive areas for hydropower plants.[3]

Hydroelectric plants in the United States

The table below shows the largest hydroelectric plants in the United States.

Largest hydroelectric plants in the United States[4]
Plant Location Date first completed Total capacity (megawatts)
Grand Coulee Washington 1942 6,809
Bath County PSP Virginia 1985 3,003
Chief Joseph Dam Washington 1958 2,620
Robert Moses Niagara Power Plant New York 1961 2,515
John Day Dam Washington 1949 2,160
Hoover Dam Nevada 1936 2,080
The Dalles Dam Oregon 1981 2,038

Environmental impacts

According to the U.S. Environmental Protection Agency (EPA), hydroelectric power plants produce no significant impact on air quality because no fuels are actually burned in hydroelectric production, although the construction and use of dams may affect water quality or disrupt wildlife and fish populations.[5]

Hydroelectric power can also impact land and water surrounding power plants. Because hydroelectricity usually requires a dam, hydroelectric plants could affect rivers or alter nearby ecosystems and wildlife. For example, colder water with less oxygen can be released into a river from a hydroelectric plant, resulting in the death of fish downstream that rely on warmer water. Dams can also release significant amounts of water all at once, which could cause flooding. On the other hand hydroelectric plants do not produce solid waste or release polluted water back into rivers or streams.[6]

See also