Zebra mussels have infested Forest Lake, on the north edge of the Twin Cities area, making it the fourth Minnesota lake this year with newly discovered populations of the invasive pest.

A member of the public found a suspected zebra mussel on a rock on the east shore of Forest Lake last week and brought it to the Comfort Lake Forest Lake Watershed District office. Additional inspections found 11 more along the eastern shore, and more along the south shore of the lake.

The number and distribution of the mussels indicate that a population is likely established and natural reproduction is occurring, said officials from the Minnesota Department of Natural Resources. As a result, treatment in the lake would not be effective and is not planned, they said.

The tiny, striped invasive mussel filters nutrients from lake water, leaving it clearer but with less food for fish and other native aquatic species. They are prodigious hitchhikers, adhering to the sides of boats, personal watercraft and heavy equipment. Despite statewide efforts, they are continuing to spread.

DNR officials reminded anglers and boaters Friday to follow aquatic invasive species laws, which include cleaning aquatic plants and debris from their boats, remove drain plugs and disposing of unused bait in the trash. The DNR also recommends letting boats and equipment dry for at least five days or washing them with high pressure or hot water before launching them in other waters.

More information about aquatic invasive species laws and zebra mussels, how to inspect boats and other water-related equipment, and a current list of designated infested waters is available on the DNR website at www.mndnr.gov/ais.