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How Hydropower Works

Generating hydroelectricity starts with the annual hydrologic, or water cycle, providing seasonal rain and runoff from snowpack. The runoff from rain and snow collects in lakes, streams and rivers and flows to dams downstream. The water funnels through a dam, into a powerhouse and turns a large wheel called a turbine. The turbine turns a shaft that rotates a series of magnets past copper coils in a generator to create electricity. The water then returns to the river. From the powerhouse, transmission lines carry electricity to communities.