Where does the debris in the Susquehanna River end up, once it goes through Conowingo Dam?
Where does the debris in the Susquehanna River end up, once it goes through Conowingo Dam? (Nils Johnson/For The Aegis)

In recent years, Conowingo Dam has become a frequent target of blame from environmental groups and some Maryland state officials, most recently Gov. Larry Hogan, for contributing to Chesapeake Bay pollution.

Never mind that there several other dams along the Susquehanna River above Conowingo, or that there are scores of other rivers and creeks that empty into the Bay other than the Susquehanna. Conowingo Dam is easy to pick on because the dam is large, located in Maryland and is owned by an out-of-state corporation, Exelon, which presumably has deep pockets and needs to deal with regulators in states where it operates its core businesses of producing and distributing electricity.


What’s curious to us is how all of a sudden, as some would tell it, the bay is becoming more polluted because a 90-year-old dam no longer effectively traps soil and other particles eroding along a watershed that stretches for thousands of square miles upstream, nor is it capable of containing the other larger detritus, much of it manmade, that also journeys southward.

Some of the most immediate concern has arisen because during the period from July 24-26, amid several days of almost nonstop rainfall in Maryland and other states that border the Susquehanna, the operators at Conowingo began to open the dam’s spill (or flood) gates to compensate for the rising river. At the river’s peak flow – approximately 365,000 cubic feet per second on the evening of July 26 – 20 of the dam’s 50 spill gates were opened, according to an Exelon spokesperson.

'Clamming' operations continue at Conowingo Dam to remove river debris

Efforts continue at Conowingo Dam to remove the unusually large river debris field that has piled up this winter behind the Harford County side of the dam.

The river crested a short time later and gates were gradually closed over the next eight hours, but some of the debris that had been backed up behind the dam likely got through and headed downstream, prompting state officials to warn about hazards to boaters. As would be expected, some of the junk ended up on local shorelines or continued down the bay. It’s important to keep in mind, however, that this was not a major weather event in terms of the dam and its operation. According to Exelon, a flood emergency plan downstream isn’t activated until at least 30 gates are opened.

Surely, Hogan and other Maryland officials have a right to be concerned about the role Conowingo Dam, and similar facilities upriver, may play in contributing to pollution of the Bay, particularly when there has been an improvement in overall water quality. Hogan said this week he doesn’t want to see a reversal in such efforts, and he called on leaders of other states in the watershed – Pennsylvania, New York, Virginia – to do more on their end.

But at the same time all this was taking place, The Baltimore Sun reported that “intense rain in July and subsequent sewer line breaks in August caused more than 85 million gallons of sewage-tainted water to flow into Baltimore’s harbor over two weeks, city officials said.”

85 million gallons of sewage-tainted water flowed into Baltimore's harbor during heavy rains, pipe breaks

Intense rain in July and subsequent sewer line breaks in August caused more than 85 million gallons of sewage-tainted water to flow into Baltimore’s harbor over two weeks, city officials said Tuesday.

“Much of the overflows were because the city’s water and sewage system releases tainted water when rains are too heavy for the system to hold,” The Sun’s report, by Luke Broadwater, continued. “Baltimore’s sewer system was designed more than 100 years ago, and city officials say the overflow problem will continue until at least 2020 while they work on $2 billion in infrastructure upgrades.”

Again, Baltimore’s sewer system isn’t the only culprit for the Bay’s pollution. The water quality of a number of Upper Bay tributaries, while improving, is still compromised by agricultural chemical runoff, failing private sewage systems and illegal waste dumping.

Where Conowingo Dam is concerned, Exelon does need to address the debris buildup – even though it didn’t create it, which will no doubt be costly. The call for a more permanent solution, such as dredging out nine decades of muck under the water, has an astronomical price tag that potentially raises its own set of environmental issues.

Maryland officials ask Conowingo Dam owner Exelon to help in 'critical moment' for Chesapeake Bay pollution

Even as Conowingo Dam owner Exelon Corp. is suing Maryland, denying responsibility for pollution that flows down the Susquehanna River, state environmental officials on Monday appealed directly to the company in a letter asking for help in "a critical moment" for the Chesapeake Bay.

Hogan has put Exelon on notice he wants these issues addressed, but it doesn’t change the fact that Conowingo Dam is not the core cause of downstream pollution. So, while the dam can’t stop as much of the sediment and junk from going into the Bay as it once did, prior to 1928 it didn’t stop any of the coal and other mining wastes coming down from the north – or the masses of ice every spring thaw that tore through buildings along the river’s Maryland shores – because there was no Conowingo Dam.

Let’s just keep the bigger picture in focus when it comes to water quality in the Susquehanna and the Chesapeake Bay and its other tributaries.