BEMIDJI -- The Minnesota Department of Natural Resources has confirmed a second infestation of starry stonewort in the state.

This time, the invasive algae was found in Turtle Lake, near Bemidji, and is about one acre in size.

Starry stonewort is a grass-like algae that's hard to control. It may produce dense mats, which could interfere with using the lake. It could also choke out native plants.

The state's first infestation was confirmed last year in Lake Koronis.

The DNR says it will explore treatment options and increase watercraft inspections, but boaters need to help prevent its spread by cleaning plants from boats, draining water and throwing away unwanted bait.

The DNR also says Wednesday that it has confirmed five new reports of zebra mussels in central Minnesota lakes.