The DNR said Friday that favorable weather conditions allowed a contractor to treat a 10-acre section of Rose Lake in Otter Tail County on Thursday for an isolated infestation of zebra mussels. It's the first time the DNR has tried to control a small, isolated population of zebra mussels. Officials say the technique has not been effective in eradicating large and established mussel populations. The treatment, using copper sulfate, is the first of three pesticide treatments occurring this fall to kill a small population of juvenile zebra mussels discovered in the lake in late September. DNR biologists believe the invasive mussels were introduced when a boat lift was placed in the 1,200-acre lake this summer.The DNR hired a licensed aquatic pesticide contractor to apply the treatment, commonly used to treat snails that cause swimmers itch. The DNR is paying $14,000 for the three treatments, which take about two hours to complete."We know copper sulfate will kill zebra mussels, but we won't know for sure until next summer if the treatment was successful," Nathan Olson, DNR invasive species specialist, said in a news release. "We will be monitoring the site closely."The DNR says Rose Lake shoreline property owners have been very cooperative. "They provided us access to the lake near the infested site," Olson said. "We couldn't have done this without them."Rose Lake will be officially designated as an infested water on Monday, Oct. 10. The designation means increased restrictions on bait harvest and transport of water from the lake as well as increased watercraft inspections and enforcement efforts.The introduction of the invasive mussels in Rose Lake remains under investigation by DNR enforcement officers.
