Conventional Sources of Electricity

Large-Scale Hydropower

Dams provide electricity by guiding water down a chute and over a turbine at high speed. Although hydropower does not produce any air emissions, dams -- especially large ones -- cause serious environmental problems.

The reservoir behind a dam often requires flooding many square miles, destroying entire ecosystems. Dams block the natural flow of water and degrade water quality, causing eutrophication behind the dams, as well as decreasing oxygen content in the river below the dam -- both of which are damaging to vegetation and wildlife populations. Dams interfere with fish migration and the flow of water, both upstream and downstream, driving many species of fish nearly to extinction. Fish ladders can partially alleviate this problem, but not entirely.