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Dams and Diversions

Related Information

Papers describing the impact of hydrologic alteration on freshwater biodiversity    Links: • World Commission on Dams • International Rivers Network • American Rivers: dam removal

Over the past 35 years, dams have been built on many of the world’s great rivers. Today, there are more than 45,000 large dams in the world, most of them in China and United States, but Asia and South America are now on a dam-building binge.

After decades of dam building and construction of water diversions, only two percent of rivers in the United States remain free-flowing and relatively undeveloped. About 60 percent of the world’s large rivers are now moderately to severely altered by dams and diversions.

Choose a link to the right to learn more about dams and diversions of our world's freshwater supply.