AIS watercraft check stations experienced increase in high-risk inspections, live mussels

Wyoming remains free of invasive mussels after challenging year

12/5/2022 6:00:29 PM

Cheyenne - The Wyoming Game and Fish Department’s efforts to keep aquatic invasive species, particularly zebra and quagga mussels, out of the state’s waters paid off in 2022. The department utilized longer hours and extended the season to inspect more than 65,000 boats for AIS. Wyoming remains one of the few states in the country not to have quagga and zebra mussels.

Game and Fish personnel conducted 65,567 boat inspections in 2022, down from 68,140 in 2021. However, the number of high-risk inspections went up from 4,187 in 2021 to 4,747 this year. 

Josh Leonard, Game and Fish aquatic invasive species coordinator, said the rise in the number of high-risk inspections was due mostly to the discovery of zebra mussels in Pactola Reservoir, 13 miles west of Rapid City, South Dakota, and 27 miles from the Wyoming border. It was the first time zebra mussels were found in a body of water this close to Wyoming, and was especially concerning because many boaters frequent waters on both sides of the state line. 

While there’s a growing threat of AIS at the state’s borders, Leonard said collaborative efforts with Wyoming Department of State Parks and Cultural Resources led to increased compliance by the public to stop at required watercraft check stations at Keyhole and Glendo reservoirs. 

“It does not surprise me that those numbers have gone up due to the increased risk we’re seeing every year with more waters becoming positive for mussels and closer to our borders,” Leonard said. “It also highlights how effective collaboration with other agencies can be.” 

AIS check stations are regarded as the first line of defense against invasives entering the state or being spread between Wyoming’s waters. Those range from invasive plants like curly pondweed, which Wyoming does have, to species that the state has managed to keep out, like Asian carp and zebra or quagga mussels. 

In Wyoming the law requires any watercraft transported into the state from March 1 through Nov. 30 must undergo a mandatory inspection by an authorized inspector prior to launching. 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. All watercraft must stop at any open watercraft check station on their route of travel, even if not intending to launch in Wyoming.

Fifty-eight boats were discovered with mussels at Wyoming check stations in 2022, slightly up from 54 in 2021. That was a big increase from 2020 when 22 boats were found to have mussels.

The Evanston port of entry continued to be the busiest check station in Wyoming. Personnel in Evanston inspected 20,422 boats this year. The next highest was at Glendo Reservoir with 8,052 inspections. The Evanston check station also had more high-risk inspections (2,590), boat decontaminations (369) and mussels found on boats (51) than any other check station in the state this year.

Keeping AIS from spreading into and within Wyoming is a priority for Game and Fish. Department personnel are evaluating watercraft inspection protocols for the 2023 boating season. 

(Breanna Ball, statewide information specialist - (

- WGFD -

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