Natural landforms and human engineering combined at Olive Lake and the Fremont Powerhouse. When Ice Age glaciers melted, they left behind Olive Lake and a moraine that formed a natural dam, creating an ideal resource for producing electricity. Engineers enlarged the dam using the log-crib earthfill method to make the lake bigger. Lake water was sent downstream to the powerhouse through an eight mile wooden pipe made of redwood and steel bands, with carefully milled tongue and groove joints that swelled into a watertight seal. The force of gravity from falling water generated electricity. Built in 1908, the Fremont Powerhouse produced electricity for nearby mines and towns until 1967, when it closed and was donated to the United States Forest Service.