More zebra mussels have been found in the Maryland portion of the Susquehanna River, state environmental officials confirmed yesterday.
The alien mussels, which can cause millions of dollars in damage to water supply and hydroelectric intake pipes and upset the local ecology, were attached to a boat at Glen Cove Marina in Harford County. Earlier this month, a single mussel was found within the intake hydroelectric station at Conowingo Dam, the first sighting in the state.
More mussels have been found six miles upstream in Pennsylvania at Muddy Run Reservoir.
Jonathan McKnight, the point man on invasive species for the Maryland Department of Natural Resources, said the agency has posted signs at launch ramps and marinas, warning boaters to wash the hulls of their vessels and trailers before moving them. BoatUS, a national recreational boaters group, has tips on its Web site, www.boatus.com.
"We've shifted from a prevention mode to a prevention and containment mode," said McKnight, chairman of the Mid-Atlantic Panel on Aquatic Invasive Species. "Boaters are the primary way the mussels move from one water body to another."
The state's invasive species task force will meet in January to develop a more comprehensive plan.
"They aren't going to spread in the winter, but come spring we're going to have to deploy a whole new program," he said.
Zebra mussels, native to Europe's Black and Caspian seas, reproduce rapidly and attach to structures and each other, building dense layers up to a foot thick. They spread by traveling in the bottom of boats or by attaching to propellers, bilges and anchors or floating docks. They entered the Great Lakes in the mid-1980s in the ballast water of a freighter and have spread to more than 20 states and parts of Canada.
The federal government estimates that zebra mussel control programs cost about $5 billion each year. Maryland has spent millions of dollars over the past decade to establish monitoring sites on waterways and build defenses at reservoirs.
The Baltimore Department of Public Works spent $3.6 million in the mid-1990s to prevent the mussels from building up in water intake pipes on the Susquehanna River and at Liberty and Loch Raven reservoirs. A system that kills zebra mussels with heated water was installed at Prettyboy Reservoir.
"The economics of zebra mussels are just crazy, because you only contain them and you have to keep containing them," said McKnight. "Anyone who pays for water or power better be paying attention because it costs a lot to rent [pipes] back from zebra mussels."