The national parks preceded the National Park Service, but the first great natural park was a state park. Californiaâs Yosemite State Park was established in 1864, by a federal cession approved by President Abraham Lincoln, and on October 21, 1880, President Rutherford B. Hayes toured Californiaâs Yosemite in an open carriage.
In fact, humans have been capturing the energy of moving water for thousands of years. Today, harnessing the power of moving water to generate electricity, known as hydroelectric power, is the largest source of emissions-free, renewable electricity in the United States and worldwide.
How does hydroelectric power work? Water is needed to run a hydroelectric power-generating unit. The water is held behind a dam, forming an artificial lake, or reservoir. The force of the water being released from the reservoir through the dam spins the blades of a giant turbine. The turbine is connected to the generator that makes electricity as it spins. After passing through the turbine, the water flows back into the river on the other side of the dam.