Buffer Zones

How wetlands protect our rivers

By Elizabeth Foy Larsen


It’s not news that nitrate runoff from fertilizers has had a troubling impact on our rivers and streams, from worsening the quality of drinking water to creating the Gulf of Mexico “dead zone” at the mouth of the Mississippi River. But while the ramifications of nitrate concentrations have been studied extensively, there has been comparatively little research on how to mitigate the damage.

That’s set to change now that researchers from the College of Science and Engineering’s St. Anthony Falls Laboratory and the College of Biological Sciences have determined that wetlands can be up to five times more efficient at reducing nitrates in water than the best land-based nitrogen mitigation strategies, especially when stream flows are high. (Other conservation practices are effective during lower flow conditions but get overwhelmed by higher water levels.)

It’s an important finding, given that the protected status of rivers and streams is uncertain under the Clean Water Act and court rulings expected this year could determine whether or not they will be safeguarded in the future. “Our work shows that wetland restoration could be one of the most effective methods for comprehensive improvement of water quality in the face of climate change and growing global demand for food,” said study coauthor Jacques Finlay, a professor in U’s College of Biological Sciences.

This research was published in January in Nature Geoscience.

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