Conowingo Dam owner Exelon sues Maryland officials over demands that it help reduce Susquehanna River pollution

A month after Maryland environmental regulators demanded the owner of Conowingo Dam do more to help reduce pollution that flows down the Susquehanna River, the company has filed two lawsuits against the state.

Exelon Corp. argues it should not be held responsible for pollution it doesn't create.


In lawsuits filed in federal and state courts, the company’s attorneys say it is “unreasonable for the State of Maryland to expect Exelon to shoulder the entire burden of removing excess nutrients and all trash at the end of a 464-mile river.”

Since its construction in 1928, the Conowingo has trapped sediment, nitrogen and phosphorus that flow down the Susquehanna from Pennsylvania and New York. That has reduced the flow of those pollutants into impaired Chesapeake Bay waterways.


But the dam is at full capacity for holding sediment, threatening progress at cleaning up the Chesapeake. As Exelon seeks to renew a federal license to operate the dam, Maryland regulators in April stepped in to say the company should not retain that license without helping to prevent pollution and trash from reaching the bay.

The Maryland Department of the Environment imposed water quality requirements on the company that Secretary Ben Grumbles said were necessary to “hold our partners accountable for doing their part to create a healthier watershed.”

The requirements mandate Exelon to trap the same amount of pollution the Conowingo always has — millions of pounds of nitrogen and hundreds of thousands of pounds of phosphorus every year. The pollutants degrade waterways by causing algae blooms and blocking sunlight, and the Susquehanna is a key source of them for the bay. The river is the source of about half of the Chesapeake’s fresh water.

Regulators also ordered the company to more frequently collect trash and debris from the dam’s edge, and to pay millions of dollars in fees if it cannot meet all of the requirements.

In the lawsuits, filed last week in both the U.S. District Court for the District of Columbia and in Baltimore Circuit Court, Exelon says those fees could total $172 million a year. The company says that is greater than “the economic value of the [dam] as an operating asset.”

“For the first time in the nearly century-long operation of the Conowingo Project, the Certification makes the Project’s owner responsible for cleaning up pollution that it did not create and has no reasonable way to remove,” the federal lawsuit says.

The federal complaint names Grumbles and D. Lee Currey, director of the department’s Water and Science Administration, as defendants. In the state court filing, Exelon’s energy-generating business arm is suing the Maryland Department of the Environment.

Exelon officials said in a statement that the Chesapeake Bay cleanup “is a shared responsibility and we need to engage multiple states and stakeholders in an effective long-term solution.”


Maryland officials said they would defend the requirements in court, calling them “the heart of our multi-state strategy to deliver the results Marylanders expect and deserve.”

Exelon officials said they “continue to evaluate the long-term viability of the Conowingo Dam.”