Conowingo Remains a Conundrum

A Baltimore Sun article (2019-07-07) highlighted the ongoing threat to Chesapeake Bay restoration efforts by polluted sediment coming down the Susquehanna River and through the Conowingo Dam. The issue continues to be heavily debated as the Conowingo’s owner, Exelon Corp., is negotiating a new 50-year operating license for the Dam with the federal government.

The Dam’s reservoir previously served as a trap for this sediment, but as the article indicated, the reservoir has reached capacity, holding some 200 million tons of sediment and muck. This means that when the Dam’s floodgates now open during heavy rain events, sediment trapped in the reservoir and any additional sediment coming down the Susquehanna is released into the upper Bay (and sometimes beyond).

However, the Susquehanna also carries significant loads of dissolved nitrogen and other nutrients, mostly from Pennsylvania, that are unaffected by the Dam’s sediment-trapping capacity and these must be addressed upstream at their source.

Some stakeholders cited in the article discussed the importance of addressing the sediment issue:

“The situation behind the dam is a ticking time bomb,” said Genevieve Croker, spokeswoman for the Clean Chesapeake Coalition, a grouping of rural Maryland counties that have Republican Gov. Larry Hogan’s ear.

However, others stressed that targeting upstream pollution sources was more important:
“The most effective approach has always been to better manage upstream sources,” said William Ball, a scientist who directs the Chesapeake Research Consortium.

[Exelon Corp.] stresses that the Conowingo itself is not a source of pollution and agrees that the problem lies upstream. …

“The momentum [to address Bay pollution] in Pennsylvania has never been stronger,” said Deborah Klenotic, a spokeswoman for Pennsylvania’s Department of Environmental Protection.

The article also discussed the negative effect climate change could have on the situation as heavier rainfalls would lead to more days where the Dam’s floodgates had to be opened. The article noted that pollution from the Susquehanna was one of the reasons scientists are predicting a 2-mile oxygen “dead zone” in the Bay this summer. This dead zone, which is incapable of supporting aquatic life, is one of the biggest in the last 20 years. Finally, the article noted concerns over whether Pennsylvania will meet its water pollution reduction goals under the federally-mandated Chesapeake Bay Total Maximum Daily Load.
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