Generating electric power from flowing water is one of the oldest and cleanest ways to produce energy. It’s one more element in the U.S. strategy to move to a diverse clean-energy economy and reduce emissions from carbon-based fuels.


  • Is a renewable energy source providing power at lower cost, with less pollution than many alternatives.

  • Generates enough U.S. electricity to offset 200 million metric tons of carbon emissions each year, equivalent to the emissions from more than 42 million passenger vehicles, according to the Department of Energy (DOE).

  • Supplies about 7 percent of the electricity generated in the United States and about half of the electricity from all renewable sources.

  • Has received U.S. government investments of more than $6 billion in the last decade. A new DOE report describes great potential for new hydropower generation in U.S. waterways, creating opportunities to expand a clean energy source and reduce fossil fuel use.

  • Relies on a variety of sources, including giant dams like Hoover Dam in the United States as well as smaller-scale power sources like municipal water facilities, stream diversion or even irrigation ditches.

The United States and Canada share the benefits of dams along the Columbia River.

Droughts can limit hydropower. Several years of drought in the American West have diminished hydropower capacity.

Even with this downside, hydropower remains highly flexible and can rapidly respond to fluctuations in the demand for electricity with pumped storage. Pumped-storage hydropower plants, often described as “giant batteries,” account for the bulk of utility-scale electrical energy storage in the United States and worldwide.

(This list is adapted from DOE’s “Top 10 Things You Didn’t Know about Hydropower.”)