BRANDON HANSEN / KCHW NEWS

Montana authorities intercepted a pontoon boat carrying invasive mussels at the Anaconda watercraft inspection station earlier this month. The boat, which had previously been in the Mississippi River in Minnesota, was en route to Loon Lake, Washington.

During inspection, mussels were found on multiple parts of the vessel, including the hull, transom, lifting strakes, anchor locker, livewell, and motor intakes. Although the boat had been out of the water for three years, it had spent an entire year in the Mississippi River prior to storage and had been shrink-wrapped—allowing mussel shells and potential larvae to persist.

Inspectors performed a partial decontamination on the boat’s exterior and locked it to the trailer to prevent further movement. Washington state officials were notified immediately to ensure follow-up measures.

This incident highlights the serious risk that aquatic invasive species, such as zebra and quagga mussels, pose to Pacific Northwest waters—even years after a boat has been removed from an infested source.

Boaters are urged to always “Clean, Drain, and Dry” their vessels and equipment and to stop at all inspection stations. For more information, visit http://www.stopais.org.