The United States has made significant progress cleaning up the nation's waterways since Congress passed the Clean Water Act in 1972, but much more remains to be done. Although some of the most obvious signs of contamination have disappeared, other sources of pollution persist, and water resources are frequently overtaxed, particularly in the West.

Reading the Map: Click the markers to see some of the nation's most remarkable and imperiled bodies of water and learn what NRDC is doing to save them.