Another Ramsey County lake has been hit with a full-scale zebra mussel infestation, the state Department of Natural Resources (DNR) reported Thursday.

A zebra mussel specialist initially found six zebra mussels near McCarrons Lake's public access in Roseville, and then a DNR survey found six more just north and south of the access. Those zebra mussels were attached to rocks and muskgrass in 1 to 3 feet of water, the agency reported.

A target search by Ramsey County staffers determined there was a lakeside presence. Other county lakes with zebra mussels are Bald Eagle, Johanna and White Bear Lake.

Once in a lake, zebra mussels are virtually impossible to stop. They can change a lake's plant community and food supply, ultimately filtering out nutrients until the water becomes crystal clear. Their sharp shells can cut the feet of swimmers, foul boat motors and damage water pipes.

Regardless of whether zebra mussels have been found in a lake or river, the DNR requires boaters and anglers to clean watercraft and trailers of aquatic plants and invasive species. Watercraft should be drained by removing all plugs and keeping them out in transit, and unwanted bait should be disposed of.

Because some invasive species are small and difficult to see, watercraft and trailers should be sprayed with a high-pressure wash, rinsed with very hot water or dried for at least five days.

Rochelle Olson