Posted on October 3, 2025
The deal puts an end to a years-long battle over who should be responsible for mitigating pollution that gets trapped in the dam and released downstream during storms, eventually making its way into the Chesapeake Bay.
A previous attempt in 2019 to forge an agreement that included a $230 million investment was met with appeals and legal challenges. In 2022, a panel of three judges on the U.S. Court of Appeals for the D.C. Circuit threw out a deal that allowed then-dam operator Exelon to avoid any investment in cleaning up pollution. Constellation now runs the dam.
After the courts tossed out the previous license, Moore and other state officials brought the dam operator and environmental advocates together to hash out a settlement that all stakeholders could live with. The negotiations took about a year, and the final agreement has the support of the environmental advocacy groups who filed the legal challenge against the old deal.
“All parties — including environmental groups who challenged a previous framework — have signed on,” Maryland Environment Secretary Serena McIlwain said in a statement. “From restored fisheries to enhanced recreation and tourism, the benefits of a healthier Susquehanna River flow through our communities, our industries, and the Chesapeake Bay.”
The state relies on clean waterways for its $3.2 billion tourism industry and its nearly $600 million seafood industry.
Most of the sediment and chemicals that end up trapped behind the Conowingo Dam come from farms upstream in Pennsylvania and New York.
Companies that have run the dam have long argued that because the dam does not create pollution, they should have limited responsibility for cleaning up that mess. In fact, the dam operators have argued that the dam prevents millions of pounds of sediment and trash from ever reaching the bay.
The agreement announced Thursday strikes a balance between both sides, with Constellation committing to invest more than $340 million to keep the Susquehanna River clean and support critical aquatic species that have historically been harmed by the dam.
“This was a once-in-a-lifetime opportunity for Maryland to secure water quality conditions that would help restore aquatic species and habitats and mitigate the sediment that surges downstream with every major rain event,” said Robin Broder, acting executive director of Waterkeepers Chesapeake, one of the groups that challenged the old deal.
Constellation President and CEO Joe Dominguez said the deal secures clean energy for the state of Maryland over the next 50 years, while also protecting a river that many Constellation employees and their families also enjoy.
“Many of us, including myself, enjoy recreational activities on the Susquehanna below the dam,” Dominguez said. “This is our backyard.”
Dominguez also emphasized the economic importance of keeping the hydroelectric plant running to supply affordable and clean power, especially at a time when the state and region are facing increasing demands for energy as more vehicles and businesses become electrified, more companies embrace artificial intelligence and the data economy continues to grow.
“To be part of a settlement here that really brings together a lot of different coalitions who have been arguing about this for years and create a pathway to keeping the bay clean for generations to come and also using it as this wonderful source of clean power for the region,” Dominguez said, “it’s a win-win-win from our perspective.”
Now that the state has entered into an agreement with Constellation and other stakeholders, the 50-year license application and settlement can go to the Federal Energy Regulatory Commission, which has the authority to permit the hydroelectric facility to operate. That process could be delayed by the federal government shutdown that began Wednesday, but state officials said they hope it will pick up again when the shutdown ends.
Most of the stipulations in the agreement are front-loaded, so that Constellation’s major investments — including in a new mussel hatchery — come in the first five to 10 years of its 50-year license.
The agreement also includes a commitment to put $18.7 million toward studying the scientific and economic viability of dredging some of the sediment trapped by the dam, which was a major goal for environmental advocates that they say would not have been in the final settlement if they hadn’t been involved.
“We’ve been in this for 16 years, working to make sure that the dam is licensed with both fair and responsible conditions,” said Ted Evgeniadis, executive director of the Lower Susquehanna Riverkeeper Association. “We know that the impacts from Conowingo are real and we were fortunate we took the right steps and the necessary legal action to get us to this point today.”
