River Conservation and Preservation

There is increasing uncertainty regarding the possible effects of global climate change on worldwide patterns of rainfall and snowfall. Hence, the conservation and preservation of rivers and their corridors have become even more important. Surveys show that the supply of potable, or drinkable, water is poorly distributed around the globe and that the largest unpolluted rivers are far from the centers of densest population. Human use, especially damming and agricultural use, has affected over 77 percent of the annual discharge of the large rivers in the northern third of the world. Many studies show that there are approximately 36,000 dams over 15 m (45 ft) high that, when full, contain 20 percent of the annual runoff—rainfall not absorbed by soil—for the globe. While offering some benefit to humans, these dams have reduced the ability of rivers to transport water and sediment to the ocean. This change affects the ecology of rivers as well as the biology of the oceans receiving the river water. Some of the oldest dams have stopped functioning because their reservoirs have filled with a huge amount of sediment. Dams also block the passage of fish upstream to spawning grounds. Some of these dams are now being removed and their river corridors restored for fisheries and wetlands, but at a tremendous cost.

The Clean Water Act of 1972 passed by the United States Congress and similar laws in other countries have changed the way that pollution is allowed to enter river systems. In the 1960s some rivers were so badly polluted that they actually caught fire and burned, including, in 1969, the Cuyahoga River in Cleveland, Ohio.

The Clean Water Act

Understanding The Clean Water Act

Today those once-polluted rivers have new parks on their banks. Conservation of rivers is also important in other parts of the world. People in the countries that share the Rhine River watershed in Europe are working together to help salmon return to the river.