Less than two months after an Eastern Shore coalition challenged Maryland’s $340 million settlement with Constellation Energy to relicense the Conowingo Dam, opposition to the deal has fallen apart.

Last month, three of four counties that had signed onto the Clean Chesapeake Coalition’s administrative appeal of the dam deal backed out.

Then, late this week, the last jurisdiction backing the appeal, Cecil County, also withdrew, marking an end to a short-lived challenge of the long-awaited settlement.

The deal, which Gov. Wes Moore, Constellation’s CEO and environmental groups announced at the foot of the dam in October, secures hundreds of millions of dollars in environmental programs for the Chesapeake Bay and paves way for the dam to keep operating for another 50 years.

Charles D. “Chip” MacLeod, the attorney for the Clean Chesapeake Coalition that filed the appeal, confirmed in an email that his group submitted letters to both Maryland and federal regulators Friday withdrawing their appeal of the state’s water certification, a key part of the state’s deal that is critical to securing a new operating license for the dam.

The withdrawal comes as a relief to Maryland leaders, who had argued that the Eastern Shore-based group’s challenge threatened to delay — or even upend — a windfall of environmental funds for the state and the long-sought relicensing of Conowingo, Maryland’s largest source of renewable power.

Maryland Department of the Environment officials toured the Eastern Shore in recent weeks to lobby the four counties, all Republican-led, to reconsider their position.

Their effort paid off.

In a statement Friday, Cecil County Executive Adam Streight said “productive, transparent discussions” with MDE over the holidays helped clarify the state’s settlement.

Cecil County, which wraps around the northern end of the bay and borders the lower Susquehanna River, can bear the brunt of storm surges through the Conowingo Dam. As part of its discussions, Streight pointed to assurances for environmental projects on the bay’s northern shores, municipal reimbursement for damages from sediment and debris that passes through the dam, and a place on a council advising on distribution of the settlement funds.

“As our concerns were addressed, we felt comfortable withdrawing our appeal,” said the Cecil executive said.

MDE Deputy Secretary Adam Ortiz was one of the officials who visited Eastern Shore county council meetings to pitch them on the downstream benefits of the state’s deal. Ortiz had offered any county that withdrew opposition a seat on a council advising on implementation of the settlement funds, and he expressed optimism Friday about the agreement now that the challenge has fizzled.

“I think it’s critical that all of us in the Chesapeake watershed are aligned in support of [the agreement] and that we have a clear path ahead,” Ortiz said. “I’m feeling much better about it today than I was in 2025.”

Under the settlement announced in October, Maryland issued a water-quality certification for the dam and Constellation pledged $341 million in environmental improvements for the Chesapeake Bay, including debris removal, improved fish passage infrastructure and a new Susquehanna River mussel hatchery.

Also included is almost $19 million to study and potentially lay groundwork for dredging behind the dam, long a priority of some environmental groups.

For decades the Conowingo Dam acted as a buffer for downstream pollution into the Chesapeake Bay, but in recent years the reservoir behind the dam filled up with sediment. Heavy rains now drive silt and nutrient pollution through its floodgates and into the bay.

In the Clean Chesapeake Coalition’s appeal, filed in November, MacLeod argued that closed-door meetings with Constellation and environmental groups violated state law and also insisted that the settlement didn’t go far enough to ensure dredging.

Conowingo’s last license lapsed in 2014, and the nearly century-old dam has operated in a state of regulatory limbo since then.

Relicensing of the dam has faced many twists and turns over the last decade and still hinges on approval from federal energy regulators.