Hydropower harnesses the force of moving water to create electric power. It is far less expensive than fossil fuels or nuclear energy, and does not contribute to greenhouse gases, although there are environmental concerns involving the effects of reservoirs.

The main advantage of hydroelectric dams is their ability to handle seasonal and daily peak demand. When demand slows, hydroelectric sites store water, and when demand jumps, more electricity can be generated.

Hydroelectric power does not always require a dam, though, and “run-of-the-river” projects use only portions of the stream flow.  These projects have virtually no adverse environmental impact.