Originally published on Waterkeepers Chesapeake Journal

The Conowingo Dam, on the Susquehanna River, has held back sediment and other pollutants for decades, but recent research shows that the Dam reservoir has filled up with sediment and associated nutrients much faster than expected.

This enormous artificial repository can be scoured by high flow events, re-mobilized, and delivered downstream by one catastrophic-level storm (think Hurricane Agnes level). If mobilized and delivered downstream, this sediment can and will smother aquatic grasses that provide food, habitats and oxygen for marine life in the Chesapeake Bay. It’s not a matter of if a major, catastrophic-level storm will happen, but when.

Recently, the owner and operator of Conowingo Dam – Exelon Corporation – filed an application with the Maryland Department of the Environment (MDE) to re-license the Dam for another 46 years. Exelon is required to obtain a 401 Water Quality Certification from MDE, which is a requirement under the Clean Water Act that the Dam will continue to meet the State’s water quality standards. MDE has the opportunity to approve, deny or place “conditions” on the Dam’s license through this process.

On December 5th, Waterkeepers Chesapeake and Lower Susquehanna Riverkeeper attended a hearing on this re-licensing and recommended that MDE place conditions on the Dam’s license to ensure that Exelon plays a role in the cleanup efforts around the Dam. Without these necessary conditions, MDE must deny the application outright due to its major deficiencies.

Conowingo Dam is a ticking time bomb that requires some major cleanup efforts. The state must address two separate problems – the sediment that is trapped in the Dam’s reservoir and the sediment now flowing through the Dam due to the Dam’s inability to trap any more sediment. This will require dredging the trapped sediment, a suite of upstream best management practices to minimize the sediment flowing through the dam, and resiliency measures downstream to ameliorate the effects of a sediment scour event – like a major storm.

We recommend that MDE require a myriad of cleanup actions as a condition on the license in order to address the complex problem that is Conowingo Dam. One type of cleanup effort alone will not be enough. For instance, while best management practices (BMPs) upstream can and should be a part of the cleanup efforts, previous studies have shown that if every single upstream BMP were instituted, they would only address about 15-20% of the sediment flow coming downstream and through the dam. Unfortunately, these practices would also do nothing to ameliorate the risk of the trapped sediment behind the Dam from releasing during a catastrophic storm.

There is an obligation, not only under the state’s 401 Water Quality Certification, but under the Federal Power Act to address water quality improvements and ensure public benefits, like access and public recreation, which will be impacted if not addressed through this license.

Over the next 46 years, Exelon will bring in billions in revenue for the operation of this Dam, and the Federal Power Act requires a public benefit for using the public resource of the Susquehanna River. Exelon may not continue to profit from this public resource without remediating all of the environmental problems the Dam has created.

If Maryland doesn’t deal with the trapped sediment behind the dam, all of our efforts to clean up the bay and meet the state’s 2025 Total Maximum Daily Load (TDML) goals will be devastated by one major storm. Maryland cannot wait to start these cleanup efforts – Maryland must partner with Exelon and other stakeholders and start the process now.

Ask MDE to ensure that Exelon plays a role in waterway cleanup efforts during the re-licensing of Conowingo DamWe can’t wait another 46 years before taking action! 

The public has until January 15, 2018 to submit written comments to MDE on the re-licensing of Conowingo Dam.