Conowingo Dam Federal Energy Regulatory       Commission Relicensing

View of the Conowingo Dam on the Susquehanna River in the aftermath of Tropical Storm Lee. Photo taken at 4:30 p.m., September 12, 2011. Photograph by Wendy McPherson, courtesy of U.S. Geological Survey.

FERC’s Relicensing Proceedings of the Exelon’s Conowingo Dam Hydroelectric Project.


The Coalition, on behalf of each of the Maryland counties that serve as its members, has filed its Motion to Intervene in the relicensing application process associated with the Exelon’s Conowingo Dam hydroelectric project.  This intervention presents the most significant opportunity to save the Bay in our lifetime, given that the license renewal is for a term of 30-50 years.   The Coalition’s intervention will hopefully move the Federal Energy Regulatory Commission (FERC) to impose significant conditions upon the relicensing of the Dam. These conditions would require the cleanup of the toxic conditions which exist in sediment of the  Dam's reservoir, thereby minimizing further contaminants from entering the Bay.


In the 2010 TMDL, the United States Environmental Protection Agency (EPA) estimated that the Conowingo Reservoir trapped 55% of the phosphorus and sediment that flowed down the Susquehanna River.  That assumption is actually incorrect and is unsupported by the recent studies of the United States Geological Survey (USGS) scientists upon whom the EPA relied to make its erroneous trapping assumption.  The Conowingo Reservoir is no longer a significant trap of phosphorus or sediment.  Not only are the sediments flushed into the Bay from the Susquehanna River and scoured from the Conowingo Dam reservoir harmful to the Bay’s health, they are detrimental to the State’s fiscal health by having direct negative effects on local shoreline communities and their economies, as well as the multi-million dollar price tag associated with the dredging and maintenance  of  the polluted sediments. 


In determining the sediment and nutrient loading from the Susquehanna River Basin, there exists another critical scientific fact that both EPA and MDE have overlooked. Toxic levels of both nitrogen and phosphorus have bound to the sediments that have been deposited into the lakes and reservoir above the Conowingo Dam.  These nutrients are inert, meaning they stay bound to the sediments, while the sediments stay behind in the reservoir and lakes above the Conowingo Dam.  However, once those sediments are transported and violently churned through the Dam and into the Bay, changes in water temperature, pH, salinity and the level of dissolved oxygen cause the nutrients bound to the sediments to be quickly dispersed into the Bay, despite the fact that such nutrients were not released into the water while they remained in the Susquehanna River. The end result is that tremendous damage is caused to the Bay because these sediments were not subject to any dredging or other cleanup while they remained stagnant in the reservoir above the Dam.

Conowingo Dam Spring Melt




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