Hydropower is renewable energy source with a very long history of use. In fact, the world's first hydroelectric power plant began operating in 1882, on the Fox River in Appleton, Wisconsin. One extremely important factor that makes hydropower so reliable is the longevity of hydroelectric power plants.
According to the Energy Information Administration (EIA) hydroelectric power plants are the oldest power plants still in use in United States with the average operating time of the hydroelectric facility in United States being 64 years.
EIA recently reported that the 50 oldest electric generating stations in the U.S. are all hydroelectric power plants, all of which have been operational since 1908.
Despite this longevity and reliability, hydropower still only accounts for approximately 7 percent of U.S. electricity generation each year.
There are four U.S. states which heavily depend on hydroelectricity, for at least half of their in-state generating capacity. These are Washington, Idaho, Oregon and Vermont. EIA also reported that three states account for more than half of U.S. total hydropower capacity. These are Washington, California and Oregon. Only two U.S. states, Delaware and Mississippi, still lack any hydroelectric facility.
Despite plenty of talk about solar and wind, hydropower is still the biggest source of renewable electricity in United States.