Policy

Mitigating Effects of Pollution and Eutrophication in the Aquatic System

Canalized streams and ditches drain much of the agricultural land in the United States.  The water carried away in these ditches is high in nitrates and other pollutants, and eventually finds its way through the watershed to end up in the Gulf of Mexico or some other endpoint. These endpoints become highly eutrophic from the nutrient overload--choked with alga and devoid of oxygen. CAC researcher Jennifer Tank and her research team have evidence that the amount of nitrogen taken up by plants in and around streams and rivers could be increased with changes in stream management.  Tank’s team, including CAC fellows Laura Taylor Johnson and Jake Beaulieu, are working with The Nature Conservancy's on a two stage ditch design project.  By changing the design of agricultural ditches, researchers believe they may be able to increase both nitrogen retention and nitrogen loss via bacterial denitrification, thereby decreasing the amount of nitrogen carried downstream.

The “two-stage” ditch design that the Center fellows are investigating essentially incorporates a mini-floodplain into the ditch shape.  This design allows more nitrogen uptake by plants, decreasing the nitrogen load as it moves downstream. Although more expensive to construct, this design offers other advantages, such as reduced flooding and maintenance. These economic benefits add to the attractive potential of two-stage ditch design to reduce eutrophication and pollution of our aquatic ecosystems.