UM scientists launch new Conowingo pollution study

Boring down: UM scientists take closer look at Conowingo Dam's role in polluting Chesapeake Bay.

Wading into a politically fraught issue, a team of Maryland scientists is trying to pin down how much of the sediment and nutrient pollution fouling the Chesapeake Bay after big storms comes from the Conowingo Dam and how much from other sources farther up the Susquehanna River.

Expected to take two years, the new study announced this week by the University of Maryland Center for Environmental Science comes on the heels of a joint federal and state assessment that the sediment buildup behind the dam is playing a relatively small but still significant role in degrading the upper bay.

That review, which took three years, concluded that dredging enough silt from behind the dam to restore its pollution-trapping capacity would cost up to $3 billion, and would provide only modest and temporary help.

A coalition of mostly rural counties, though, has argued that dredging would do more to help the bay than other costly and unpopular cleanup measures communities are being required to carry out, such as curbing storm-water runoff and dealing with pollution from household septic systems.

“This new study builds on the considerable work that has been done and presents a rare opportunity to conduct cutting-edge research on a modern-day challenge for which big decisions are awaiting the results,” Donald Boesch, the center's president, said in a statement announcing the review.

Scientists will bore down in the silt upriver of the dam to analyze the buildup, while others will refine computer models assessing how sediment and nutrients get scoured out from behind the dam during big storms. The estimated $3.5 million cost of the study is being funded by Exelon Corp., which is seeking to renew its federal license to generate power at the hydroelectric dam.

News of the study was welcomed by a spokeswoman for Gov. Larry Hogan, who has sided with the rural counties and questioned the study finding dredging wouldn't help much. He has vowed to shift the focus of Maryland's bay cleanup efforts to the sediment buildup behind the dam and to pressuring Pennsylvania and New York to reduce their pollution of the Susquehanna.

Erin Montgomery, Hogan's press secretary, said the governor was "encouraged" by the UM study.

"The Conowingo Dam is at about 92 percent capacity for sediment storage and is losing its ability to trap sediment from reaching the Chesapeake Bay, our state's most treasured natural resource," she said.

"By understanding the true impact of the dam," Montgomery added, "and by working with upstream states and federal partners, we can invest in the best solutions for a cleaner and healthier bay--and this study is a good first step." 

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