An Aquatic Invasive Species (AIS) technician at Grand Teton National Park recently discovered quagga mussels on a boat arriving from Utah. The mussels, which measured about 6–8 mm (about the width of a pencil) were found during a routine AIS inspection at one of the park’s check stations. Although the mussels were no longer alive, their presence is a serious concern.

The boat was decontaminated and sealed for a mandatory 30-day dry period, in accordance with Grand Teton National Park policy.

Wyoming remains one of only five states with no bodies of water that have tested positive for or been infested by quagga or zebra mussels. Once introduced and established these species often cause dramatic ecological and economic damage, making prevention critical.

“Finding mussels at a Grand Teton AIS check station is uncommon but it’s a good reminder that the risk of an introduction is real,” said Chad Whaley, fisheries biologist and AIS coordinator. “We cannot become complacent. The risk level is not going down.”

AIS check stations have operated in Grand Teton National Park since 2015 and serve as the final line of defense in protecting the park’s waters. 

Protecting Grand Teton National Park’s waterways is a shared responsibility. Prevention is an essential duty for boaters, anglers, and resource managers alike. Grand Teton National Park works with numerous partners throughout the community and region to support and enforce AIS prevention.

Park leadership extends appreciation to the vigilant technician who identified the mussels and to the cooperating boater. Both played a vital role in helping keep Grand Teton and Wyoming’s waters free of invasive species. The park also thanks the public for supporting watercraft inspections before launching in Grand Teton waters.

Boaters are reminded that they are required to stop if they pass an open watercraft inspection station, regardless of prior inspection history or destination. Out-of-state boaters must be inspected before launching on any waters in Wyoming. Arriving with a clean, drained, and dry watercraft speeds the inspection process and helps protect aquatic resources.