Bay Restoration Initiatives: Conowingo Dam

Conowingo Dam
The Conowingo Hydroelectric Generating Station at the mouth of the Susquehanna River.
Image courtesy of Jane Thomas - IAN, UMCES


What is the Conowingo Dam?

Located near the mouth of the Susquehanna River, Conowingo Hydroelectric Generating Station, also known as Conowingo Dam, is a hydroelectric power plant owned by Exelon Corporation (Leaving MDE). The dam was originally constructed in 1928 and has been in operation ever since. Special attention has recently been drawn to the Conowingo due to it losing its ability to trap nutrient and sediment pollution, and the application by Exelon Corporation to renew their Hydropower license to operate the dam.

What Challenges does the Conowingo Face?

The Susquehanna River provides almost 50% of the freshwater entering the Chesapeake Bay. The river carries about 40% of the nitrogen, and 25% of the phosphorus and sediment that enter the Bay. Conowingo, like other dams, has a large reservoir behind the dam that traps some of the nutrient and sediment pollution. However, over time the sediments, nitrogen, and phosphorus have gradually accumulated behind the dam, filling the reservoir and causing the Conowingo to stop trapping nutrient and sediment pollution.

What is a Hydropower License and why is it Required?

To protect water quality and safeguard the river from environmental harm, operators of hydroelectric dams periodically required to obtain a Hydropower license to continue operation. Hydropower licenses are reissued by the Federal Energy Regulatory Commission (FERC) every 30-50 years. Applicants for license renewal must first obtain a water quality certification from the state in which the project is located. Conditions specified in a State water quality certification become conditions in the federal license.

How is Exelon Corporation Renewing Their Hydropower License?

Exelon Corporation applied for water quality certification of the project on May 16, 2017. Maryland Department of the Environment has one year from the application date to make a final decision.

Learn more about the Conowingo and its environmental impacts (Leaving MDE).


Contact Information

Please direct questions or comments to Dinorah Dalmasy