Efforts by the Minnesota DNR to stem two budding zebra mussel infestations through chemical means have yielded – at best — mixed results.
The DNR used copper sulfate to treat two lakes – Rose and Irene – in Otter Tail and Douglas counties last fall after a few immature zebra mussels were found in the lakes.
The good news: Inspections of the lake this summer did not turn up evidence of larval zebra mussels known as veligers. That would have been proof zebra mussels were reproducing in the lakes.
The bad news: Inspections this fall found adult zebra mussels, proof the copper sulfate did not eradicate the zebra mussel population.