Image by Steve Hersey via Wikimedia Commons.

By creating ponds that slow down the movement of rivers and streams, beavers aid in removing nitrogen from the water, according to researchers from the University of Rhode Island. Image by Steve Hersey via Wikimedia Commons

According to University of Rhode Island (URI) professor Arthur Gold, beavers can help prevent harmful levels of nitrogen from reaching vulnerable estuaries. URI researchers found that the water retention time and the build-up of organic matter in beaver ponds lead to ideal conditions for nitrogen removal. These conditions can result in removal of 5% to 45% of nitrogen in the water, depending on the pond and amount of nitrogen present.

Gold, who led the study published in the Journal of Environmental Quality, said nitrogen levels have been increasing in Northeast waters for years. Nitrogen from urban and agricultural sources, such as fertilizers and septic systems, is released into small streams and ponds and eventually travels to estuaries. High levels of nitrogen in these water bodies can stimulate algae blooms, which can lead to low oxygen levels.

However, with beaver populations recovering from widespread trapping, beaver ponds can make a notable difference in the amount of nitrate flowing from streams to estuaries. Smaller streams, where beavers make their homes, often are the first to be developed, according to URI doctoral student and study author Julia Lazar. It may be important to conserve or reduce the effects of development to preserve the beaver’s benefits to water quality.