Since Conowingo Dam’s construction in 1929, sediments flowing down the Susquehanna River have been building up in its reservoir. Recent studies by the U.S. Geological Survey indicate that the reservoir is effectively full of sediment which means that more of those sediments, and the nutrients associated with them, are washing downstream into Chesapeake Bay during storms. A follow up study led by the Department’s of Environment (MDE) and Natural Resources, the U.S. Army Corps of Engineers, Susquehanna River Basin Commission and EPA’s Chesapeake Bay Program (CBP) found that those sediments and nutrients are contributing to dissolved oxygen impairments in the Chesapeake Bay. CBP has quantified the nutrient contribution from Conowingo infill as resulting in an additional 6-million pounds of total nitrogen and 260,000 pounds of total phosphorus load that is affecting dissolved oxygen levels in Chesapeake Bay. Governor Hogan has made addressing Conowingo Dam’s impacts a top Chesapeake Bay restoration priority.
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