Officials say invasive mussels may have found their way to Isle Royale National Park in Lake Superior.
Superintendent Phyllis Green says Monday divers have found an apparent zebra mussel population in Washington Harbor on the island park's west side.
Also, Green says a single mussel was found at the eastern end of the 45-mile-long park. Officials are trying to determine whether it's a zebra mussel or its cousin, the quagga mussel.
Zebra and quagga mussels are natives of eastern Europe and were brought to the Great Lakes in ballast tanks of oceangoing freight-hauling ships.
They've caused millions in damage by clogging water intake pipes and have disrupted the food web across the region.