Ghosts of Land Use Past

Typography

UD researcher examines how removing milldams might impact water quality.

All over the eastern part of the United States, thousands of small dams span streams and rivers, harkening back to colonial times. Originally constructed for energy and milling operations by settlers or companies, most of the milldams no longer serve their original purpose. Now, many of these inactive dams are being removed by government and private agencies — driven by a need or hope of increasing public safety, reducing liability and improving aquatic habitats.

However, less attention is being paid to how removing the dams could impact water quality, which is precisely what University of Delaware Professor Shreeram Inamdar is investigating. As the researcher explained, backup of the water and the rise of stream water level upstream of the dam unintentionally provides a valuable benefit. Streamside soil upstream of the dam is rich in carbon and that combined with the wet conditions, acts as an important filter of nitrogen, a key pollutant in our nation’s waterways.

“This natural filtering service in riparian soils reduces stream water nitrogen concentrations, improves water quality and saves limited conservation resources,” said Inamdar, who serves as director of UD’s Water Science and Policy Graduate Program. How dam removals could influence this service is not well known.

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