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Conowingo Dam Owners Must Clean Up Their Act


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View Seth Johnson's blog posts
17 July 2013, 9:41 AM
Dam allowing sediment to dirty Chesapeake Bay
Conowingo Dam. (Michael Jewel)

The Lower Susquehanna Riverkeeper, Stewards of the Lower Susquehanna and Waterkeepers Chesapeake today asked to be included in the relicensing proceedings for the Conowingo Dam, about 50 miles northeast of Baltimore. The dam affects water quality up and down the Susquehanna River and throughout Chesapeake Bay, and the groups plan to push the Federal Energy Regulatory Commission to require the dam’s owner to take action so that the dam doesn’t harm waters in Maryland, Pennsylvania and beyond.

Only 10 miles from where the Susquehanna pours into the Bay, Conowingo Dam is an ecological time-bomb. Behind the dam lies a massive amount of sediment, a water pollutant that clouds the waters of the Chesapeake Bay, harming underwater vegetation and the animals that rely on it. The dam has been trapping about 55 percent of the incoming sediment in the Susquehanna, but according to predictions by scientists the dam is running out of room to store sediment. And as it runs out of room, more and more sediment pours into the bay. The current plan to clean up the bay doesn’t have a plan to address this problem—and neither does the request for a 46-year permit from the dam’s owners, Exelon Generation.

What’s more, major storms scour sediment that’s built up behind the dam, leading to giant influxes of sediment, phosphorus and other pollutants into the bay. Tropical Storm Lee, in 2011, swept a 100-mile-long plume of sediment—visible from space—from the Susquehanna into the bay.

Sediment Clouds the Chesapeake Bay. (Jeff Schmaltz / MODIS Land Rapid Response Team, NASA GSFC)

Exelon Generation, a subsidiary of energy giant Exelon Corporation, wants to get a new license from the Federal Energy Regulatory Commission that will let it keep running until 2060. But Exelon does not include a plan that addresses the sediment that’s built up and will keep building up.

The Lower Susquehanna Riverkeeper, and 17 other Waterkeeper groups dedicated to protecting the Chesapeake Bay and its tributaries, don’t think that makes sense. Nor is it fair: the Susquehanna and the Chesapeake belong to everyone, and Exelon should have to do its share to help clean them up.

As well as causing a sediment problem, the dam is a problem for American eels. These fish spend most of their adult lives in rivers like the Susquehanna, but return to the Sargasso Sea to spawn. Well, eels used to live in the Susquehanna in enormous numbers, but dams like the Conowingo make it virtually impossible for them to travel up and down the Susquehanna to complete their life cycle. Now there are millions fewer American eel upstream of the dam. Some have made it thanks to a small-scale trap-and-transport program but many (maybe most) will die as they try to pass back through the potentially lethal turbines of the Conowingo Dam and other upstream hydropower dams. 

The American eel is important for the ecosystem and water quality in the Susquehanna. The eel are the best, and almost unique, host for the larva of certain mussels. These mussels filter the river’s water, making it cleaner. But there simply aren’t a lot of these mussels in the Susquehanna anymore. Restoring the American eel could help reinvigorate the mussel population and clean the water, and the Waterkeeper groups will make the case for Exelon to work harder to bring the American eel back to the Susquehanna and make sure they survive the return to their spawning grounds.

The Waterkeeper groups also plan to urge FERC to have Exelon reopen access for fishing from the dam’s “catwalk,” a platform that runs across the face of the dam. It was an important part of the local heritage from 1928 to 2001. The catwalk gives access to striper fishing, the prize catch of the lower Susquehanna River. Current fishing access makes it difficult for older and disabled fishermen to reach the areas where the stripers are mostly found, over 100 feet from the shoreline fishing areas.

I support Earthjustice and the Waterkeepers entering the Conowingo Dam relicensing case for all the reasons given in this article, including especially the need to reduce sediment pollution at the source. U.S. water resource authorities must stop using lakes and reservoirs as sediment receptacles, with the bogus assumptions that "dirt pollution is OK," or "we'll simply dredge the sediment out periodically."

The reality is that the increasingly frequent big storms do the "dredging" for us, with costly damage to downstream resources as the result. Instead, we need to institute upland source prevention throughout the contributing watersheds, starting with land use policy changes that keep more land in forests and sustainable farms. This is the rural protection part of the "Smart Growth" equation.

Diane Cameron
Audubon Naturalist Society
Chevy Chase, Maryland

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