Conowingo DamExelon Corporation owns and operates the dam. Exelon’s current license expired in 2014, and it is seeking a new 50-year license from the Federal Energy Regulatory Commission (FERC). Before FERC grants a new license, the State of Maryland must certify that the project will meet state water quality standards. This water quality certification is required under section 401 of the federal Clean Water Act.

On April 27, 2018, the Maryland Department of the Environment issued a Water Quality Certification with special conditions for the proposed relicensing of the Conowingo Dam. The certification requires Exelon to reduce nitrogen and phosphorus pollution in amounts equal to what had previously been trapped by the dam (six million pounds of nitrogen and 260,000 pounds of phosphorus a year). However, it does not put concrete measures in place to achieve these reductions. Instead, the certification directs Exelon to develop a nutrient management plan to meet its obligation. The certification does not include specific requirements to reduce sediment.


Waterkeepers Chesapeake and Lower Susquehanna Riverkeeper (Waterkeepers) believe that Maryland’s Water Quality Certification is incomplete because it is missing several key elements. Therefore, Waterkeepers, represented by Earthjustice, filed a motion to reconsider the State of Maryland’s Water Quality Certification of Conowingo Dam.


Exelon has filed a case in federal court – the U. S. District Court for the District of Columbia – that challenges the authority of the State to require nutrient pollution reductions as part of the 401 Certification. On July 20, Waterkeepers filed a motion to intervene in support of the State of Maryland. While Waterkeepers believes that the State’s 401 water quality certification is missing key elements, it strongly supports the State’s legal authority to impose nutrient pollution reductions on the dam’s owner as part of the relicensing process.


Waterkeepers filed motions to intervene in Exelon Corporation’s federal court action versus the Maryland Department of the Environment, in which Exelon challenges the authority of the state to require nutrient pollution reductions as part of the 401 Certification.