Take Action to Strengthen the Cleanup Plan for Conowingo Dam

The recently released draft Conowingo Dam Cleanup Plan, known as a Watershed Implementation Plan (WIP), has serious flaws that need to be addressed: it doesn’t address reducing sediment pollution, there is no financing mechanism, and it doesn’t account for increasing pollution loads due to climate change. We are asking you to take action and submit comments by January 21, 2021.


Conowingo Dam, May 2019. Photo credit John Pavoncello

When the Chesapeake Bay Cleanup Plan, known as the Total Maximum Daily Load (TMDL), was established in 2010, it was believed that the Conowingo Dam would continue to trap a portion of the sediment and nutrient pollution flowing down the Susquehanna River, at least through 2025. This trapping capacity was factored into the projections of how much pollution reductions would be needed to restore the Bay. New research has determined that the reservoir behind Conowingo Dam has effectively filled-in, and larger pollution reductions are needed to meet the Bay’s water quality standards than originally calculated. In December 2017, the Chesapeake Bay Program began working on a separate Conowingo WIP. The draft Conowingo WIP has been issued and public comments are being accepted through January 21, 2021.

What about the 200 million tons of sediment pollution?

The Conowingo WIP offers no clear plan to address sediment behind the dam. At the start of the Conowingo WIP planning process, dredging analysis and planning was supposed to be a high priority in the final Conowingo WIP. This current draft makes very few references to dredging, and concludes only that “more study is needed” on dredging. Nearly 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 and debris behind the dam and send that downstream to the Chesapeake Bay and nearby tributaries like the Sassafras River. 

Where’s the money?

The Conowingo WIP does not yet have a financing plan—creating great uncertainty at the outset as to how any work in the draft Conowingo WIP will be funded or actually executed. To make matters worse, the Conowingo WIP does not hold the owner of the dam, Exelon, financially accountable for the pollution built up behind the dam. Analyzing planning documents for the Conowingo WIP shows that the drafters’ interest in holding Exelon accountable to the process waned over time with the burden falling to the Bay states and their respective taxpayers. Exelon has no definitive role, financial or otherwise, in the draft Conowingo WIP.

The importance of the Conowingo WIP is even more critical when viewed in light of the fatally flawed settlement agreement between the State of Maryland and Exelon. In this agreement, the state waived its Clean Water Act authority to require water quality certification, and allows Exelon to avoid paying its fair share of the costs of the clean up. The proposed settlement provides, at best, less than $1 million per year to address sediment and nutrient pollution over the entire 50-year license. The actual cost of meaningfully reducing the nutrients and sediment behind the dam has been estimated at approximately $41 – $172 million each year.

What about increasing pollution loads due to climate change?

The draft Conowingo WIP leaves out an essential element—increased pollution loads due to climate-driven increases in rainfall, flooding, and extreme storms. Without the climate load factored in, it is impossible for the Conowingo WIP to facilitate necessary load reductions.

Take Action!

Fill out the form below to send a comment letter by January 21. You can view recorded stakeholder webinars here.