ST. PAUL (AP) -- Zebra mussels have spread to two more Twin Cities metro lakes.

The Minnesota Department of Natural Resources said Friday that both Lake Waconia and White Bear Lake will be designated as infested after zebra mussels were confirmed in the lakes this week.

DNR biologists found three of the invasive mussels in Lake Waconia in the western Twin Cities and three in White Bear Lake in the east metro.

Both lakes were investigated after reports from the public.

Zebra mussels can crowd out native mussels and compete for food with other aquatic animals.

The pests attach to boat hulls, and their sharp shells can cut swimmers.

The DNR says people should watch for aquatic invasive species when removing docks, boat lifts, swim rafts and other equipment from the water.