An April 7 Washington Post article summarized the divergent points of view over whether or not the reservoir behind the Conowingo Dam should be dredged to address the sediments released from the Dam into the Susquehanna River and upper Chesapeake Bay watershed.  The debate on dredging the Conowingo has temporarily suspended the efforts of the dam’s owner, Exelon, from being relicensed by the federal government and Maryland to operate the dam for up to another 50 years pending the outcome of a 2-year water quality analysis. From the article:

To Larry Hogan, Maryland’s new Republican governor, the dam is an environmental hazard. Over the course of nearly a century, more than 170 million tons of sediment has built up in a huge reservoir designed to trap it before it reaches the bay.  …

Hogan has said that a dredging operation costing up to $250 million might be the answer to the bay’s pollution problem, and that the dam’s owner, Exelon Corp., should pay most of that cost.

Exelon calls the governor’s concern misplaced and says dredging isn’t the answer. To back that claim, executives who manage the dam pointed to a November study by the Army Corps of Engineers and the Maryland Department of the Environment said another type of pollution — nutrients from phosphorous and nitrogen that run off farms and municipal sewer overflows — is far more harmful to the Chesapeake.

The article described how the report has led to a split between different stakeholders on whether dredging is the appropriate answer, with Hogan and groups like the Clean Chesapeake Coalition in favor of dredging while the Army Corps, Exelon, and environmental groups like the Chesapeake Bay Foundation standing by the report’s conclusion that dredging will not help the Chesapeake Bay.

Dan Bierly, chief of the civil project development branch at the Army Corps, stood behind the research, saying it “brought together the foremost experts in this field” and used “the best and most trusted mathematical models” to arrive at the conclusion that “sediment itself doesn’t really pose a major threat to the bay.” …

The sudden reversal on concern about the impact of sediment held by [former Maryland Governor] O’Malley, the U.S. Geological Survey and numerous conservation groups was greeted with suspicion by the Hogan administration. “It was kind of surprising to us that all of a sudden the Army Corps was reversing their concern about the dam,” said Adam Dubitsky, policy director for Hogan. …

[Clean Chesapeake Coalition General Counsel Chip] MacLeod said turning the focus away from sediment is the goal of a multibillion-dollar federal plan to clean up the bay by limiting nutrient pollution. Run by the Environmental Protection Agency and managed by states in the bay watershed, including Maryland, the “pollution diet” is supported by the Army Corps and regional environmental groups. …

“They were going to find a way to conclude [sediment] wasn’t the most important thing to focus on,” MacLeod said, to support the “pollution diet and structure” that the EPA and environmental groups favored. …

But environmentalists say the coalition’s position ignores the best available science. Beth McGee, senior water-quality specialist for the Chesapeake Bay Foundation, said it was “one of the groups that was concerned and that sediment at the dam was a ticking time bomb.”

The Army Corps study ended the foundation’s concern about sediment and the need to dredge it.

Prior Conduit Street Coverage of the Conowingo Dam Relicensing