Promising Zebra Mussel Treatment In Lake Minnetonka Targets Larvae

As the threat from damaging zebra mussels spreads across Minnesota waters, there’s hope a new control method could bring some relief.

In a first of its kind study, researchers are out on Lake Minnetonka targeting zebra mussel larvae. They’re in one of the more heavily infested parts of the lake in Robinson Bay. That’s where six test enclosures will be treated with a chemical solution to stop the mussels before they form.

Ever since zebra mussels were first found in Lake Minnetonka, they’ve been spreading wildly. Fouling boats, docks and sandy shores, and disrupting the natural food chain. This first of a kind study aims to finally get an upper hand.

It’s hard to believe zebra mussels spread from first detection to all out infestation in just six short years. Robinson Bay on Lake Minnetonka is among the worst hit.

That’s why crews with Minnehaha Creek Watershed District and the University of Minnesota have turned the bay into their outdoor laboratory where they’ve set out to control a tiny creature threatening the lake’s sensitive ecosystem.

They’re using a new approach with a copper-based pesticide. Instead of targeting the adults, they’re attacking the zebra mussel larvae, called veligers, to find the most lethal and efficient dose.

“If you can reduce the number of veligers that they put out in peak times of the summer, over time you can reduce the population significantly,” AIS Program Manager Eric Fieldseth said.

Following each treatment, researchers will evaluate the effectiveness of different concentrations.

“If we get something that has low, non-target impacts, that’s all the better of use,” Fieldseth said.

Eradication from every weed or rock will be a tall order, but slowing their spread is a vital first step in what to this point has been a very disruptive and uncertain future.

The month-long study was primarily funded by a $24,000 grant from Hennepin County. The district hopes to have results by the end of the year.

The treatment is considered very safe, and it has the blessings of the EPA. The copper solution is species-specific and poses no health risks to humans or other aquatic life.