Pennsylvania environmental officials reported Nov. 24 that a single zebra mussel was found in a water intake of 572-MW Conowingo Dam on the lower Susquehanna River in Maryland. Conowingo’s nine-mile-long reservoir extends into Pennsylvania.
The Pennsylvania Environmental Protection Department and the state’s Fish and Boat Commission said the half-inch eastern Europe native was discovered during monitoring of juvenile shad migration at Conowingo, a hydroelectric project operated by utility Exelon Corp. (HNN 3/20/07) It had not yet attached itself to the intake.
The officials said it was the first time a zebra mussel, Driessena polymorpha, has been found in the lower Susquehanna. Carried to North American waters in ballast waters of ocean-going ships, zebra mussels first infested the Great Lakes and moved into other water bodies across the continent, often carried by recreational boats.
The species poses a serious threat because it plugs industrial and water intakes and disrupts aquatic food chains by filtering out plankton upon which fish and other organisms feed.
“Controlling zebra mussels has cost more than US$1 billion since they were first discovered in the Great Lakes in 1988,” acting Environmental Protection Secretary John Hanger said. “It will require constant vigilance by fishermen, boaters, and others who use our waterways to keep these invasive creatures out of the Susquehanna River and its tributaries.”
The agencies said the mussels have been found to pose an additional threat, creating new pathways for diseases like Type E (Avian) Botulism, further damaging ecosystems.
“The best thing anglers and boaters can do is to disinfect boats, trailers, boots, and gear before entering a new body of water,” Fish and Boat Commission Executive Director Doug Austen said.