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THE CONOWINGO DAM: Safeguarding Communities and the Bay


For 90 years, the Conowingo Dam has served as Maryland’s largest source of reliable and renewable energy. In keeping with their commitment to environmental stewardship, dam operators prevent more than 600 tons of debris from entering the Chesapeake Bay each year. During severe weather and dangerous Susquehanna River conditions, operators must open the dam’s floodgates to protect local towns from flooding and preserve the integrity and safety of the dam. 


Several recent news accounts following a period of severely high water flows unfairly pointed to debris in the Bay as evidence that Exelon Generation is not committed to the environment. That is simply not true.
Supporter Stories
Read and share community stories in support of the Conowingo Dam on the Support Conowingo Dam website.

Supporter Quotes 

"In terms of being able to see foraging, number of birds and the amount of activity, I don’t think anything rivals Conowingo." 

Dr. Bryan Watts, Director, Center for Conservation 
"The debate over relicensing Exelon to operate the Conowingo hydroelectric generating plant due to the sediment and nutrients washing down the Susquehanna River seems misplaced. One would get the impression that running the electric turbines somehow creates silt and phosphorus rather than electricity. The sediment and nutrients come from runoff in central Pennsylvania and New York State. Some seem to think that the dam created the accumulated silt and nutrients in the lake behind the dam, but those too came from upstream, and if there had been no dam to block them, they would have been washing into the Chesapeake for the past 85 years.

Conowingo generates about 550 megawatts of power, similar to a full sized coal generating station, but cheaply and with no air or water pollution, so we should promptly authorize its use and keep it running. Yes, preventing more pollution of the Bay from the Susquehanna must be addressed. However, not using the existing electric turbines will have no effect on the accumulated silt or new materials washing down the Susquehanna into the Bay, but will increase electric costs and greenhouse gas emissions. It is a perfect lose-lose-lose decision."

George Hamilton, St. Michaels
"(They) claim to be concerned about the pollution and sediments coming down the Susquehanna River and over the Conowingo Dam. Dredging the sediment behind the dam is pointless unless we reduce the upstream sources. The multi-state WIP, overseen by the federal Environmental Protection Agency, is our best hope of forcing Pennsylvania and New York to do their part to clean up that river. It deserves everyone’s support…

… We have known what needs to be done to clean up the Bay for decades, and we need to get on with it."

George Kaplan Colora

 "In response to recent coverage that the Maryland Department of Environment could deny Conowingo a permit to generate electricity ("MDE intends to deny Conowingo Dam permit," Nov. 20), Conowingo should be expeditiously relicensed by FERC and permitted to generate electricity by MDE.

The arguments surrounding the sediment contribution to the Chesapeake Bay have been extensively examined in the Army Corps of Engineers' recently released federal assessment. It shows that the negative contribution to Bay quality stems from nutrients collected in the entire watershed and passed downstream of Conowingo. The sediment scour effect at Conowingo is significantly less contributory. Discussions to-date about sedimentation have chased the wrong contributor. This study finds that nutrients are the longer term culprit. Best watershed management practices across NY, PA and MD are the logical solution path, not dredging.
This political football must be addressed by knowing the science revealed in this study. Stakeholders must take the time to digest the study and follow its lead in mitigating the nutrient's contribution, not pursuing the folly of dredging sediment.
Enhance the Bay.

Relicense the dam and look at the whole watershed issue, not just Conowingo.YES"

Paul English, Severna Park

"…Consider the Conowingo Dam's impact on Maryland's economy: $273 million in economic benefits to the state each year, including $10 million in state and local tax collections annually. The dam supports 265 full-time equivalent local jobs and also annually attracts 250,000 recreational visitors, who enjoy hiking, swimming, fishing, boating and bird watching in the dam's picturesque environment. Conowingo also provides prime breeding, nesting and foraging grounds for the American Bald Eagle and helps 1 million migratory and native fish travel over the dam for spawning in the Susquehanna each year. There are even additional plans to further develop recreational resources offered by the dam through the provision of new access facilities.
Perhaps most critically, the dam captures 2 million tons of sediment per year — sediment that would otherwise enter the upper Chesapeake Bay and wreak havoc on its vital ecosystems. It represents the last line of defense against harmful pollutants that would damage a national treasure.

Relicensing the dam is a no-brainer for Maryland. It fortifies our economy and protects our natural resources. Accordingly, the Conowingo Dam has proven worthy of our collective support."

Anirban Basu, Chairman and CEO of Sage Policy Group, Inc. and consultant to Exelon Generation

​"The Conowingo dam has done a wonderful job of supplying our power cleanly for the last eight decades ("Support the dam to support Md.," Oct. 13). Let's renew its license so we can continue to benefit from its clean power for decades to come."

Machele Varady

"Some of my fondest memories are from my time spent at the Conowingo Dam. As someone that has spent a lot of time at the recreation areas around Conowingo Dam and seen its operation firsthand, a recent Aegis editorial about sedimentation behind the dam got it wrong.

The dam is one of the best recreational places in the entire state and is important to the bay's ecological health. The fisherman's wharf is a great spot to observe the many fish species of the Bay, including bass, shad, catfish and walleye. In addition, the fish lifts have transported more than 1 million migratory fish annually to the Conowingo Pond, according to Exelon, the dam's operator.

I agree that the pollution in the Chesapeake Bay is an important issue to address, but Conowingo Dam is not creating that pollution - it's actually preventing the silt and sediment created further upstream from harming the Bay. It is misguided to demand Exelon pay for its cleanup, and the dam's relicensing should not divert our attention from the actual task at hand: a regional solution to cleaning up the Chesapeake Bay and its tributaries.

I support Conowingo Dam and we need to relicense it so that people like me can continue enjoying it for decades to come."

Stephanie Campbell, Bel Air


​Fact Sheets/Resources

Conowingo Hydroelectric Generating Station is a run-of-the-river hydroelectric power plant owned and operated by Exelon Power, a business unit of Exelon Generation.​

Exelon Generation Company, LLC (Exelon) is licensed by the Federal Energy Regulatory Commission (FERC, or the Commission) to operate the 573-megawatt (MW) Conowingo Hydroelectric Project (Conowingo Project) (FERC No. 405). The current license for the Conowingo Project was issued on August 14, 1980 and expires on September 1, 2014.

Exelon currently owns and operates two hydroelectric generating stations in Maryland and Pennsylvania. These two hydroelectric power plants provide more than 1,600 megawatts (MW) of reliable, environmentally friendly power generation. 

Conowingo Hydroelectric Project, FERC Project No. 405-106 
Lodging of Filings Regarding Clean Water Act Section 401 Certification Challenges​

Exelon Generation shares the State of Maryland’s commitment to restoring and sustaining the health of the Chesapeake Bay. For 90 years, the Conowingo Dam has been a source of reliable, clean energy, today accounting for 55% of the renewable energy in Maryland. The Dam does not produce any pollution. Rather, the science clearly shows that the pollutants that travel down the Susquehanna River, from New York and Pennsylvania, are the source of the nutrients and sediment that flows into the Bay. 


The facts on the Conowingo Dam. ​ 

What is the Dam? 
  • ​The Conowingo Dam is the largest source of renewable energy in the State of Maryland 
  • Because water is used to turn the turbines, Conowingo can be used to "jump start" the electric distribution system in the event of a system failure of the PJM connection
  • The Conowingo Pond, which is created by the Dam holding back the water of the Susquehanna River, is used as a public water supply source for the City of Baltimore and Chester Water Authority (CWA) 
How does the Dam contribute to water quality/pollution? 
  • The Conowingo Dam does not produce any pollution
  • The pollutants that travel down the Susquehanna River, which spans over 27,500 square miles, from New York and Pennsylvania, are the source of the nutrients and sediment that flow into the Bay
What happened with recent storms? 
  • The Susquehanna, along with 11 other waterways, saw 10 times the normal water flow and significantly more debris floating downstream during recent storms
  • Debris from upstream mixed with debris from below the Dam and collected in downstream communities, like Annapolis
  • In 2018, we’ve seen one of the largest volume of debris flowing downriver in 10 years because of winter storms, ice flows on the Susquehanna River, and heavy rains that affected the entire watershed
Does Exelon Generation remove debris
  • Exelon voluntarily removes an average of 600 tons of trash and debris around the Dam each year​
  • We deploy crews to operate overhead cranes and grapple devices to clear debris from the river as safely and efficiently as possible
  • When safe, we will also launch debris skimmer boats to assist with cleanup
  • Although Exelon Generation voluntarily removes debris from the river, no one can remove all debris from the upstream watershed, especially during flood conditions
How does Exelon Generation do its part to support the Chesapeake Bay? 
  • Each year, Exelon sponsors two events--the Lower Susquehanna Heritage River Sweep and Conowingo Pond clean-up day--where we remove more than 100 tons of debris and refuse from the river each year
  • Exelon donated $25,000 to the Chesapeake Bay Trust to support local debris clean up efforts​


​Our View 
As owners of the Conowingo Dam, Exelon Generation shares the concerns of the public regarding the safety and the health of the Chesapeake Bay, in particular the amount of trash and debris across the bay. The overwhelming majority of the debris​ entering the bay comes from upstream on the Susquehanna River watershed, which spans over 27,500 square miles of New York, Pennsylvania and Maryland, and passes through the dam. 

Along with the 11 other rivers that feed into the bay, the Susquehanna recently experienced 10 times normal water flows and significantly more debris swept into the river and through the dam because of heavy rain. Although we seek to remove debris from the river safely and efficiently, we cannot remove all debris especially during flood conditions. We’ve removed more than 600 tons of debris that has flowed down to the dam so far this year and will continue to do so. 

We look forward to continuing our work with local and state authorities to protect and restore the health of the bay.

Read what others are saying​ 
We’ve seen a number of key stakeholders eager to talk about Conowingo’s benefits. Here are several Letters to the Editor we’ve seen so far.

Aegis Opinion ​​​(Baltimore Sun – August 10 2018)

Chesapeake Bay: Better but not enough​ (Baltimore Sun – July 19, 2018)

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