Environmental Integrity

Water Energy (Hydroelectric Power)

The Basics

Download Resource File

TITLE: Water Energy (Hydroelectric Power) – The Basics

AUTHOR: Office of Energy Efficiency and Renewable Energy

SOURCE: Office of Energy Efficiency and Renewable Energy, U.S. Department o Energy

COPYRIGHT: No protection is claimed in original U.S. Government works.



Hydropower, or hydroelectric power, is one of the oldest and largest sources of renewable energy, which uses the natural flow of moving water to generate electricity. Hydropower currently accounts for 31.5% of total U.S. renewable electricity generation and about 6.3% of total U.S. electricity generation.

While most people might associate the energy source with the Hoover Dam—a huge facility harnessing the power of an entire river behind its wall—hydropower facilities come in all sizes. Some may be very large, but they can be tiny, too, taking advantage of water flows in municipal waterfacilities or irrigation ditches. They can even be “damless,” with diversions or run-of-river facilities that channel part of a stream through a powerhouse before the water rejoins the main river. Whatever the method, hydropower is much easier to obtain and more widely used than most people realize. In fact, all but two states (Delaware and Mississippi) use hydropower for electricity, some more than others. For example, in 2020 about 66% of Washington state’s electricity came from hydropower. 


Hydropowertechnologies generate power by using the elevation difference, created by a dam or diversion structure, of water flowing in on one side and out, far below, on the other side. The Department of Energy's "Hydropower 101" VIDEO BELOW explains how hydropower works and highlights some of the research and development efforts of the Water Power Technologies Office (WPTO).

Environmental Justice Intake Form
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.