ALEXANDRIA, Minn. — An effort to kill zebra mussels discovered in Lake Irene and Rose Lake was unsuccessful, according to the Minnesota Department of Natural Resources.
Last fall, DNR biologists investigated two separate cases where boat lifts used in zebra mussel infested lakes had been moved to non-infested waters — Lake Irene in Douglas County and Rose Lake in Otter Tail County.
The DNR attempted to eradicate zebra mussels by treating both areas with copper sulfate, a common chemical used to treat snails that cause swimmer’s itch.
While larval zebra mussels (veligers) and juvenile and adult zebra mussels were not detected during the summer, “during our fall searches, we did find adult zebra mussels in both lakes,” said Nathan Olson, DNR invasive species specialist in Fergus Falls.
Olson said the DNR cannot confirm that zebra mussels have reproduced in either lake.
The DNR also has confirmed the presence of juvenile zebra mussels in Lake Miltona, north of Lake Carlos and downstream of Lake Irene in Douglas County.
The DNR also has confirmed that zebra mussels have been found in the Otter Tail River below Orwell Reservoir.