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LOCATION: Conowingo Dam, Cecil and Hartford County, MD

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STATUS: Active

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ISSUE IN BRIEF: 

It’s critical that when a dam is relicensed requirements or conditions are in place to offset and mitigate the dam’s impact on water quality standards, fish passage, habitat, aquatic species, and recreation. The state decides what conditions are appropriate to meet water quality standards by issuing a Water Quality Certification for the dam. That Certification then becomes part of the license which is issued to the dam owner by the Federal Energy Regulatory Commission (FERC). Conowingo Dam was to be relicensed in 2014 but due to environmental study requests and legal challenges, the final Water Quality Certification for Conowingo Dam was issued by Maryland on October 2, 2025. The 50-year license has not yet been issued by FERC.

 

THE LATEST: (PRESS RELEASE) Governor Moore Announces Historic 50-Year Conowingo Dam Agreement for Landmark Chesapeake Bay Restoration Efforts to Supercharge the $3.2 Billion Bay Economy

 

On October 2, 2025, Lower Susquehanna Riverkeeper Association, Waterkeepers Chesapeake, Maryland Department of the Environment (MDE), and Constellation Energy announced a settlement agreement and terms of a final Water Quality Certification for Conowingo Dam. Constellation has agreed to fund and implement operational improvements and environmental projects to meet enforceable water quality standards by reducing and mitigating the impacts associated with the dam’s discharge and operation on the Susquehanna River and the Chesapeake Bay and its tributaries. The agreement – negotiated in partnership with Waterkeepers Chesapeake and Lower Susquehanna Riverkeeper Association – clears the way for the re-licensing and continued operation of the dam’s hydroelectric facility on the Susquehanna River.

 

The terms of the agreement include operational improvements and upfront and ongoing annual payments for water quality and resiliency projects, trash and debris removal, wildlife passage, freshwater mussel restoration, dredging, and invasive species management. Lower Susquehanna Riverkeeper Association and Waterkeepers Chesapeake have an ongoing role in aspects of the implementation of the certification and settlement agreement going forward for the next 50 years in partnership with Maryland Department of the Environment.​

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MORE ABOUT CONOWINGO DAM

The Conowingo Dam is located on the Lower Susquehanna River about 10 miles upstream from where it flows into the Upper Chesapeake Bay at Havre De Grace, Maryland. Owned and operated by Constellation, the Conowingo Dam currently has 11 turbines, which can produce up to 572 megawatts (MW) of electricity. Although the dam produces renewable power for homes and businesses, Conowingo has replaced a free-flowing section of the Susquehanna River with a 14-mile-long, 9,000-acre reservoir. This fundamentally alters the river’s ecology.

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Ever since the dam was built in 1928, it has changed seasonal river flow; blocked the migration of shad, herring, eel and other fish; destroyed fragile aquatic habitat; devastated the shellfish communities that naturally filtered the Susquehanna’s water; killed millions of fish caught in hydroelectric turbines; and altered the river’s natural ability to transport nutrients and sediment. More than 200 million tons of sediment pollution have accumulated behind the dam. During major floods caused by large storms, powerful floodwaters can scoop out or “scour” the stored sediment behind the dam and send that downstream to the Chesapeake Bay causing harm to underwater grasses, habitat, and oyster beds while releasing associated nutrients that cause devastating “dead zones.”

IN THE MEDIA:

 

DOCUMENTS AND SOURCES:

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Conowingo Dam

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