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Changes need to be made at a Maryland hydroelectric dam before its federal license can be renewed, state environmental regulators say.

The Maryland Department of the Environment announced Friday that Exelon, the energy company that runs the Conowingo Dam, needs to reduce the amount of sediment and nutrients that flow downstream, among other requirements. As part of the federal licensing process, Maryland has to certify that the facility meets state water quality standards.

“The Conowingo Dam sediment problem has been building up and ignored for decades, and this comprehensive strategy — the Water Quality Certification — requires restoration for the nutrient and sediment pollution, and also it requires a more balanced flow regime for the river,” said Maryland Secretary of the Environment Ben Grumbles. “It also includes significant improvements for fish and eel passage.”

According to the water quality certification, Exelon also needs to improve debris removal and study the feasibility of installing and running a solar trash wheel similar to ones used in Baltimore.

The dam is the largest one in Maryland, officials say. It spans the Susquehanna River, which flows into the Chesapeake Bay.

The “stringent environmental conditions” in the water quality certification will help local restoration efforts, officials say.

“It’s a blueprint for cleaner water and a healthier ecosystem, both for the Susquehanna River and the Chesapeake Bay,” Grumbles said.

The dam has been in operation for nearly a century, and Exelon is seeking a 50-year license renewal. The dam’s license expired in 2014. Maryland environmental regulators didn’t approve Exelon’s 2014 renewal application because the application lacked information about impacts to water quality. Exelon filed its current application in 2017, officials said.

The energy company said it’s committed to restoring and sustaining the health of the Chesapeake Bay.

“It is important to understand that the Conowingo Dam does not produce any pollution itself,” it said in a statement. “We are reviewing the State of Maryland’s water quality certification now and will evaluate next steps to determine the long-term viability of the Conowingo Dam.”