BURLINGTON, Vt. (AP) – Maritime Museum executive director Art Cohn says the water in Lake Champlain is becoming clearer.

As a diver and head of an organization that promotes diving expeditions at shipwrecks hidden deep within the lake, that normally would be good news.

But Cohn isn’t celebrating. That’s because the water clarity is a result of zebra mussels.

“I hate zebra mussels,” he said. “I hated the fact that they came here. I hate the fact that they’re impacting this collection of historic shipwrecks.”

First found in a southern section of Lake Champlain in 1993, zebra mussels are disliked because they clog water intake pipes and damage boats. They also coat the lake’s bottom and artifacts, kill native mussels and affect the lake’s ecosystem.

Zebra mussels are filter-feeders, consuming large amounts of microscopic plants and animals. But while divers can now see farther in the lake, what they see is disturbing.

They are also a concern in Maine. The state has included zebra mussels on its list of invasive aquatic species that can displace native species, disrupt the food chain, degrade sport fishing, damage public water supplies and lower property values.

U.S. Sen. Susan Collins, R-Maine, sponsored a bill with Sen. Carl Levin, D-Mich., to provide funds to study and control zebra mussels and other unwelcome aquatic species.

“The only thing you can see is the zebra mussel,” said Chip Perry, another dive instructor at the Waterfront Diving Center in Vermont.

The Lake Champlain Maritime Museum’s eight designated shipwrecks are becoming increasingly encrusted as well.

Besides covering pieces of history, the zebra mussels have the capability of deteriorating the ships’ wood, said Mark Ferguson, a zoologist with the state Department of Fish and Wildlife.

The mussels also degrade iron fastenings holding the ship together, Cohn said. “Zebra mussels are degrading the shipwrecks in a pretty insidious way,” he said.

Zebra mussels are believed to have been brought to the Great Lakes region of the United States and Canada around 1986 in the ballast waters of trans-Atlantic freight ships. The first zebra mussel was identified in North America in 1988 in Lake St. Clair near Detroit.

AP-ES-05-25-03 1314EDT