Zebra mussels have been found in Lake Hiawatha in Minneapolis, putting the foot-cutting, equipment-damaging invasive mollusk within a short portage of the revered Chain of Lakes.
Minneapolis Park and Recreation Board water quality workers found several of the small mussels Aug. 28 on a plate submerged in the lake as a detection device.
The lake had actually been declared infested by the Minnesota DNR in 2010, after zebra mussels were found in Lake Minnetonka and Minnehaha Creek, which flows out of Lake Minnetonka and through several other metro lakes, including Hiawatha. The Mississippi River, into which the creek empties, is also infested.
"We knew they were coming," said Deb Pilger, director of environmental, equipment and volunteer services for the park board.
In 2012, the park board increased inspections of motorboats on city lakes and restricted hours at boat ramps to try to reduce the possibility that boaters might carry the mussels into city lakes. Motorboats can't access Lake Hiawatha. Pilger said parks workers also have been limiting the transport of equipment from lake to lake.
Pilger said the finding in Lake Hiawatha heightens the risk of infestation in the Chain of Lakes.
No zebra mussels have been found in any of the Minneapolis Chain of Lakes, including Nokomis, which is only yards from the creek and is a close neighbor of Lake Hiawatha. Like Hiawatha, Nokomis was declared infested in 2011 by the DNR and managed accordingly, even though no actual zebra mussels have been found there. Nokomis and Cedar Lake in Minneapolis, both in the Chain of Lakes, have detection devices.
Zebra mussels have infested well over 100 Minnesota lakes, wetlands and streams, from Lake Superior and Lake Mille Lacs to Prior Lake and the St. Croix River, according to the DNR. Lake Hiawatha is one of more than two dozen infested waters in the seven-county metro area.
Zebra mussels proliferate quickly, affect water quality and can cause myriad problems. Their sharp shells can cut swimmers' feet, and they can form damaging masses on buoys, dock supports, boat parts and other underwater structures, including water intakes.
However, Pilger noted that zebra mussels aren't expected to thrive in Lake Hiawatha because of the lake's nutrients and plant life. Only one of its 53 acres is considered suitable for high growth rates, she said.
"I think we'll find more next year," she said. "But I don't think 2014 will be a year when people say, 'I don't want to be on that beach.' That'll take some time."