Zebra mussels have been found in lakes in Grant, Stevens and Wright counties, adding to a list of Minnesota waters that have recently reported infestations, officials said Monday.

The thumbnail-sized mollusks were found on water equipment being removed from the lakes for the season.

“This is a key time of year to check for zebra mussels and other invasive species, especially when removing docks, boat lifts and sailboats that have been in the water for a long time,” Heidi Wolf, invasive species unit supervisor for the Department of Natural Resources (DNR), said in a news release.

Wright County staffers first contacted the DNR after finding a zebra mussel attached to a boat as it was being removed from Sugar Lake. Then 13 property owners on the lake reported they had found zebra mussels on their boat lifts and docks.

DNR workers also found numerous adult zebra mussels in the north and southeast ends of the lake.

Elsewhere in Minnesota, zebra mussels were found in a chain of lakes that spread across Otter Tail, Grant and Stevens counties.

All of the lakes are connected and lie between Barrett Lake, where zebra mussels were confirmed in September, and Ten Mile Lake, where the species was confirmed last year, the DNR said.

A Grant County sheriff’s deputy contacted the DNR after finding the mussels on water equipment being removed from the Tipsinah Mounds Campground at Pomme de Terre Lake. The DNR also confirmed zebra mussels at several Pomme de Terre locations.

The DNR confirmed reports of multiple adult zebra mussels on water equipment in Perkins Lake and found an adult zebra mussel upstream between North Pomme de Terre Lake and Middle Pomme de Terre Lake, according to a news release.

In August, the DNR reported that the mussels had been found in Bald Eagle Lake, north of White Bear Lake; Lake Johanna in Arden Hills, and Lake Isabelle near Hastings.

In late September, two juvenile zebra mussels were found on a sailboat that didn’t leave Bde Maka Ska in Minneapolis all summer, officials said. No additional zebra mussels were found.

A native of Europe, zebra mussels were discovered in Minnesota in 1992 in the Mississippi River and Lake Pepin, four years after they were found in the Great Lakes.

Zebra mussels can drastically change a lake’s plant community and food supply. The tiny mussels reproduce quickly and multiply into the millions, filtering out nutrients in the water. Their sharp shells cut the feet of swimmers, foul boat motors and damage water pipes.

To slow the spread of the mussels, Minnesota law requires boaters to clean their watercraft and trailers, drain all water and dispose of unwanted bait before launching from shore.