Despite efforts to muscle up the laws on the transportation of invasive species between Minnesota bodies of water, the Department of Natural Resources says it found zebra mussels in three more Minnesota waters.
The report comes one week to the day that Forest Lake in Washington County was found to have the same problem.
Per the DNR, the invasive species was discovered in Clearwater Lake in Wright and Stearns counties, Ruth Lake in Crow Wing County, and the Red River in northwest Minnesota. All three will be labeled as "infested" with zebra mussels.
The invasive species are believed to have spread to the Clearwater and Ruth lakes via boats, docks and other lake equipment that wasn't properly cleaned after leaving another body of water.
A human element is unlikely related to the infestation in the Red River, the DNR says.
An invasive species specialist in Stearns County told the St. Cloud Times the size of the zebra mussels in Clearwater Lake likely mean it's been infested for a year or two.
Minnesota has laws in place to limit the spread or introduction of aquatic invasive species. The DNR classifies zebra mussels as a "prohibited" invasive species.
Earlier this year state lawmakers delayed the start of a law that would have mandated all Minnesotans pulling watercraft on a trailer be able to pass a 30-minute invasive species test, the Star Tribune notes. More than 540,000 motorboats are registered in Minnesota.
According to ProtectYourWaters.com, zebra mussels feast on tiny organisms in lakes. When those organisms are depleted, smaller fish and larva can starve, depleting options in the ecological food chain for sporting fish like walleye and northern.
A full list of Minnesota bodies of water infested with invasive species can be viewed here.