ST. PAUL  — Officials have confirmed the presence of zebra mussels in two more Minnesota lakes and added the Red River to the state’s official list of waters infested with the aquatic invaders.

The Minnesota Department of Natural Resources says Clearwater Lake in Wright and Stearns counties, and Ruth Lake in Crow Wing County, probably became infested because of people moving contaminated boats, docks or other equipment, or failing to drain water from their watercraft.

North Dakota last week announced the first finding of zebra mussels in the Red River north of Wahpeton.

The Minnesota DNR says it’s not surprising because the Otter Tail River in Minnesota, which flows into the Red River, has been infested with zebra mussels since 2012. It says their larvae likely colonized the Red by floating downstream.