For the first time this year, a watercraft with verified live mussels was discovered at a Wyoming check station late last month.

The watercraft harboring live, invasive zebra mussels was intercepted on Sept. 22 at the northeast Wyoming border by the Wyoming Game and Fish Department, according to a release. Inspectors at the northeast check station removed live zebra mussels in multiple water intakes, along the pontoon and in other areas of the inspected boat. The watercraft had been moored for several months in South Dakota’s Pactola Reservoir, where a population of mussels was discovered in 2022. 

The boater assisted Game and Fish by stopping for the inspection, mandatory in Wyoming between March 1 and Nov. 30 each year. Upon discovery of the mussels, inspectors at the Beulah aquatic invasive species check station immediately began decontamination of the watercraft.

The incident highlights the importance of watercraft inspections. Prior to the program’s expansion, inspection stations in Wyoming would have been closed for the season at this point in the year, and the boat may have gone unnoticed, according to the department. 

“When the AIS Program launched in 2010, our stations were only open for the main boating season,” said Josh Leonard, AIS coordinator for the Wyoming Game and Fish Department. “In the last few years, given the increased threat of AIS, we recognize the need to stay open into the shoulder seasons, when the bulk of boaters are off the water. Situations like this demonstrate the threat is at our borders — knocking on Wyoming’s door.”

Zebra and quagga mussels are aquatic invasive species that can wreak havoc in freshwater ecosystems, including causing damage to property like watercraft, ruining shorelines, harming fish populations and causing a decline in tourism. In addition, mussels can clog dam systems, municipal water pipes, irrigation systems and treatment facilities.

An infestation in just one of Wyoming’s water treatment facilities could cost hundreds of thousands of dollars annually to remove mussels, keep water flowing and mitigate damage — costs that could be passed on to all water users, the department reported.

Wyoming remains one of only five states in the continental United States that are mussel-free, with every state bordering Wyoming, except Montana, having at least one body of water containing mussels. However live, adult mussels can begin reproducing the moment they hit the water if the conditions are right, so a watercraft harboring mussels could easily start a new population.

Inspections are the first line of defense for many watercraft, and cases like this serve as a reminder for sustained vigilance, said Reed Moore, AIS Specialist for the Sheridan region.

“Our inspectors see thousands of boats every year,” Moore said. “Since the discovery of zebra mussels in Pactola, our inspectors at Beulah have conducted hundreds of decontaminations. Over 50% of the watercraft inspected there are considered high risk for transporting AIS. Luckily the risk of this watercraft was minimized by our technicians and compliant boaters.” 

Watercraft inspectors statewide have inspected over 73,000 boats and conducted 1,121 decontaminations this year. They also intercepted 43 other boats containing nonviable invasive mussels.

Any watercraft transported into Wyoming during the mandatory inspection period must undergo an inspection by an authorized inspector prior to launching on any Wyoming waterway. It’s state law that anyone with a watercraft must stop when coming upon an open AIS inspection station — even if they stopped at one prior or do not intend to launch in Wyoming. This applies to all motorized watercraft, as well as nonmotorized watercraft such as kayaks, canoes, rafts and paddleboards. 

While boating season in Wyoming is winding down, so are the Wyoming Game and Fish Department aquatic invasive species check stations. Check stations throughout the state have begun to close or reduce hours.

“Boaters who need to get their watercraft inspected between now and the end of November can stop by a Game and Fish office or contact any private, certified inspector,” said Josh Leonard, Game and Fish AIS coordinator. “Any watercraft that has been in a water infested with zebra/quagga mussels within the last 30 days is required to undergo a mandatory inspection by an authorized inspector prior to launching during all months of the year.”

Boaters planning trips can check inspection hours along their routes at the Game and Fish AIS chapter. The department also has a listing of private inspectors who may operate outside of normal hours or by appointment.  

“With the threat of zebra mussels greater than ever before to Wyoming, we are relying on boaters more than ever to do the right thing and get your boats inspected,” Leonard said. 

For more information: wgfd.wyo.gov/fishing-boating/aquatic-invasive-species-prevention/ais-inspection-locations.