More than a century after U.S. Army troops harnessed the power of flowing water to light Fort Yellowstone, the park is generating electricity from water again. The idea of tapping into a sustainable resource to power Yellowstone came to the park in 1903, when the U.S. Cavalry under the direction of engineer Hiram Chittenden installed the first 100-kilowatt water turbine generator near its Mammoth Hot Springs headquarters. Relying on water flowing from Glen Creek down through Golden Gate, the power plant supplied ample energy to power residences, administrative offices, maintenance shops, lights on the parade grounds and the occasional picture show at the Mammoth Hot Springs Hotel to great attendance.