Despite intensive efforts by lakeshore owners to prevent the spread of zebra mussels into popular Pelican Lake near Brainerd, state officials confirmed Thursday a single juvenile zebra mussel was found on a dock there this fall.

But after two weeks of further searching, officials haven't been able to find another -- meaning they don't know whether the 8,000-acre lake is infested. Usually if they find one zebra mussel, they will find many.

"This is really a unique situation," said Dan Swanson, Department of Natural Resources regional invasive species specialist in Brainerd.

Workers pulling a dock from the lake discovered the zebra mussel attached to a post. Its small size indicates it is not at a reproductive stage.

"We've done a thorough search," Swanson said. "Now we're asking for the public's help."

The Pelican Lake Association has worked hard to prevent the lake from becoming infested, said Clyde Clement, a member and zebra mussel activist who lives on the lake. All four public landings are posted with signs and staffed with inspectors during the summer. The discovery of the zebra mussel is disconcerting, he said.

"It's very disappointing -- no question about it," Clement said.

Still, he's hopeful that the discovery doesn't mean there's a reproducing population of zebra mussels in the lake.

"What a disaster that would be for Pelican Lake and the Gull Lake community," he said.

Nearby Gull and Ossawinnamakee lakes are among the 60 or so state waters infested with zebra mussels. Seven lakes have been added to the list in 2011.

Doug Smith • 612-673-7667