Wildlife

Beavers Help Remove Pollution in Rivers

The dams that beavers build, sometimes at the expense of human development, are a natural way of keeping rivers, streams and estuaries free of certain pollution.

A University of Rhode Island study found that beaver habitats, and all of the organic material used by the animals to build them, can remove a large portion of the nitrogen runoff from fertilizer used in agriculture and suburban life.

High levels of nitrogen in waterways promote the growth of algal blooms, which cause low oxygen levels that can kill fish.

Researchers found that holding back water and organic matter within beaver ponds leads to ideal conditions for nitrogen removal.

Between 5 and 45 percent of the nitrogen in the water is removed by the dams, depending on the pond and amount of nitrogen present.

Beavers were largely wiped out hundreds of years ago in Europe and parts of North America by the fur trade, but they have been making a comeback in recent decades.