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Susquehanna Life

Environmental Impact: Reconnecting Our River

Jun 06, 2016 06:04PM ● By Melanie Heisinger

Conowingo Dam

By Carol Parenzan

Although the Susquehanna River flows 464 miles from Cooperstown, New York, to Havre de Grace, Maryland, it is not one continuous river without interruption. Today, dams block natural movement of aquatic wildlife, from its source at Lake Otsego to just a few miles north of its entry into the Chesapeake Bay, negatively impacting wildlife and the environment.

Throughout the history of the Susquehanna River and its tributaries, dams were built to support the logging industry, run mills, feed water into the canal system, create recreational lakes and generate power. 

Before these dams were built, however, shad, eel, herring and other fish swam freely. Archeological discoveries have shown that shad were plentiful in northern Pennsylvania and even as far north as New York State around the latter half of the 18th century. But as dams went up, shad harvests, due in part to these river blockage structures, went down.



Oswegatchie River


In 1928, with the construction of the southernmost dam, the Conowingo, in Maryland, all but the lower 10 miles of the river and her feeding tributaries between the dam and the Chesapeake Bay became inaccessible to migratory fish. Moving fish around these concrete walls became the challenge.

From 1985 to 1996, Pennsylvania Power & Light, owner of the Conowingo Hydroelectric Plant at the time, captured approximately 350,000 migratory shad in its fish elevator. These fish were then placed into tanker trucks, transported around the next three dams, and released to continue their journey up river.

Today, there are fish passage facilities (or fish-ways) at each of the four hydroelectric dams on the lower Susquehanna River. Conowingo, Holtwood and Safe Harbor Dams use fish lifts or elevators; York Haven Dam employs a vertical slot fish ladder. These efforts, however, have proved ineffective.

According to the Pennsylvania Fish and Boat Commission, in 2015, at the first concrete obstruction as the shad begin their way up the Susquehanna River, 8,341 shad were lifted up and around the Conowingo Dam. However, that number reduced significantly by the fourth dam, York Haven, where only 43 fish found passage around the dam, resulting in an overall passage success rate of only 0.5 percent.

Shad aren’t the only swimmers of concern. Since 2008, the U.S. Fish and Wildlife Service has captured almost one million migrating eels at the Conowingo Dam and transported them to various locations in the upper sections of the river valley. Eels play host to Eastern elliptio, a common freshwater mussel, by transporting their larvae stage to other areas of the watershed, where they take up residence and improve water quality by filtering bacteria, algae and other small particles. Prior to constructing the four hydropower dams on the river, the eel population exceeded 11 million.


A better way?

Trucking fish is limited, costly and currently focuses on migratory movement up-river only. As mature fish begin to return to the Chesapeake Bay, they will have to pass through hydropower turbines, potentially causing harm, or even death. 

River scientists now employ other options to return the Susquehanna River back to its natural state. Although Pennsylvania leads the nation in dam removal projects, according to Lisa Hollingsworth-Segedy, associate director for river restoration, American Rivers, none of the dams on the Susquehanna River is being considered for removal at this time. But that didn’t keep American Rivers from listing the Susquehanna River on its 2016 America’s Most Endangered Rivers list.

According to a statement issued by American Rivers, “The Susquehanna is threatened by pollution, but is also imperiled by the Conowingo Hydroelectric Dam, which alters river flow, blocks fish and impacts water quality. [Owner] The Exelon Corporation is seeking to renew its federal license to operate Conowingo, and Maryland has the authority to require that the dam meet state water quality standards before a new license can be issued. However, a bill pending in Congress, H.R. 8, would take away Maryland’s authority to hold Exelon accountable for pollution, putting the Susquehanna River further at risk.”

Michael Helfrich,
Lower Susquehanna RIVERKEEPER®

As part of the relicensing process, the impact of the dam’s operation on the environment, including migratory fish activity, is being evaluated, and comments by environmental watchdogs, such as Lower Susquehanna RIVERKEEPER® Michael Helfrich, are being heard.

“Exelon’s commitment to the repopulation of the American eel throughout the Susquehanna watershed is promising, not only for the eels but also for the Eastern elliptio mussels that count on the eels as their host species for reproduction,” Helfrich explained. “The mussels help us with pollution reduction in the Susquehanna River and, in turn, the Chesapeake Bay.”


Other Options 

In addition to calling for action regarding the Conowingo Hydroelectric Dam, American Rivers is currently focusing on dam removal projects on several tributaries to the Susquehanna River that will further enhance the results of previous dam-removal projects by reconnecting additional habitat and continuing to improve water quality.

When dam removal is not an option, enhanced wildlife passage should be a priority. Dr. Luther Aadland, river science and restoration consultant and author, Reconnecting Rivers: Natural Channel Design in Dam Removal and Fish Passage, believes that our current focus on fish ladders and passages is too narrow.

“The passage should be designed for all aquatic life – reptiles, amphibians and fish. These passages need to emulate nature with riffles and pools,” he believes.


What’s in Store

Camp Fear Rock Ramp. Photo courtesy of Cape Fear River Watch.

Aadland is consulting on two aquatic passage projects at Susquehanna River dams – the York Haven Hydro Station Dam and the Adam T. Bower Memorial Dam (formerly known as the Sunbury Fabridam). His designs typically employ the use of rock ramps and bypass channels. Both designs for the Susquehanna use the latter, where the natural movement and drop of the river is recreated using a series of ponds and riffles through a meandering channel, providing resting spots and varying current flows to assist the widest variety of wildlife in their natural journeys both up and down the river. 

“Reconnecting the Susquehanna and allowing her to be the river again after almost 100 years would not only benefit the eco-tourism industry along the river and in the valley,” says Andrew Miller, executive director, Susquehanna River Valley Visitors Bureau, “it is respectful to both our heritage and to our future. It’s not just about restoring the fish population. It’s about taking care of Pennsylvania.”

Carol Parenzan, the Middle Susquehanna RIVERKEEPER®, holds an environmental engineering degree with a water focus from Penn State University. Please share your concerns and river memories with her at (570) 768-6300 or


Visit WebExtras for Parenzan’s sidebar, “Is it Time to Rethink Hydroelectric Dams?”

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