The DNR will add Lake Winnibigoshish in north central Minnesota to its list of waters infested with zebra mussels.
DNR biologists recently discovered two microscopic larval zebra mussels, called veligers, in samples taken last summer from the state's fourth largest lake. No adult zebra mussels have been detected, but officials say they will add Winnibigoshish and 13 connected water bodies to the infested list as a precaution.
Follow-up testing showed no additional veligers, but more testing will be done after the lake thaws, said DNR invasive species expert Ann Pierce.
"Even though we didn't find the adult zebra mussels, it's really proactive at this time to list Winnibigoshish as infested," Pierce said. "And this will allow recreationists and other resource partners to be aware that we have found zebra mussel veligers in the lake, and to take the added precautions to prevent the spread to other areas."
DNR aquatic biologist Gary Montz said if zebra mussels are reproducing in the lake, the invasive species might spread downstream.
"Eventually, there will be enough veligers in the lake that they will start flowing downstream in the Mississippi River in enough numbers that some of the downstream lakes that the Mississippi River flows into, may begin to see their own populations of zebra mussels," Montz said.
Water sampling will continue this spring and summer, including shoreline searches for the invasive species.