- Nearly 2000 years ago the Greeks used water wheels to grind wheat into flour
- In the 1700's, hydropower was broadly used for milling of lumber and grain and for pumping irrigation water
- Appleton, Wisconsin became the first operational hydroelectric generating station in the United States, in 1882, producing 12.5 kilowatts (kW) of power
- The total electrical capacity generated was equivalent to 250 lights
- Within the next 20 years roughly 300 hydroelectric plants were operational around the world
- The invention of the hydraulic reaction turbine created the sudden expansion of hydropower
- 40% of the United States' electricity was provided by hydroelectric power in the early 1900's
photo taken by Mr. Roy Schmidt; Minnesota Power, Hydropower Dam in Little Falls, MN
- The largest and last masonry dam built by the U.S. Bureau of Reclamation was the Roosevelt Dam in Arizona between 1905-1911; its power output has increased from 4,500 kW to 36,000 kW
- In 1933, the Tennessee Valley Authority Act was enacted into law
- The Hoover Dam first generated power in 1937, producing 130,000 kW
- By the 1940's, hydroelectric power supplied roughly 75% of the electricity used in the western United States and approximately one-third of the United States' total electric energy
- Still in use today, Niagra Falls was the first hydropower site developed for a vast quantity of electricity
- Nearly 10% of the United States' electricity came from hydroelectric power in 1997
- In the United States hydropower generates over 90,000 megawatts (mW); this could supply about 28.3 million customers (estimated population in 2001 was 284.4 million people) which is still less than 10% of the populace.
