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Riparian Buffers Keep Nitrogen Pollution at Bay

EPA studies inform decisions about how much vegetation should be left along waterways


Letting trees and other vegetation grow along stream and river banks is a relatively inexpensive and environmentally effective way to reduce the amount of excess nitrogen runoff reaching the water.

Photo of trees by a river

But how wide do these riparian buffer areas need to be to achieve the desired effects?

EPA scientists Paul Mayer, Tim Canfield, and their colleagues are conducting research to provide answers. Their studies reveal that 50-meter wide buffers reduce nitrogen pollution by about 85 percent; while 26 to 50 meter buffers reduce nitrogen by about 70 percent. Buffers 5 to 10 meters wide are much less effective, only occasionally reducing excess nitrogen runoff that reaches these flowing waterways.

Since Mayer's and Canfield's work was published, it has been used to develop new management practices by several states, including North Carolina, Pennsylvania and Maryland, as well as local water resource management entities in Washington, North Dakota and Colorado.

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EPA’s Wetland Management Research

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