Quagga mussels attach to a boat’s propeller in this photo from outside Yellowstone. The invasive mussels are most commonly introduced into other ecosystems by motorized boats. Yellowstone National Park could ban non-Park Service boats if the mussels are found near or in park waters. (National Park Service)

Greg Mayton knew the impact zebra or quagga mussels could have on an ecosystem. But the Cody-based aquatic invasive species specialist with Wyoming Game and Fish Department always figured the threat would come from the state’s southern borders. Then in 2016 the aquatic invasives were found in Montana’s Tiber and Canyon Ferry reservoirs prompting Glacier National Park to temporarily close its waters to boating and Yellowstone to prepare to do the same if the mussels were detected any closer.

“I thought we were pretty safe up here in the northwest corner of the state and then I got the email and I was dumbfounded,” Mayton said.

Wyoming is one the last few states zebra and quagga mussels haven’t invaded and staff at Wyoming Game and Fish are working hard to keep the state’s water mussel-free, at least for as long as possible.

Quagga and zebra mussels are filter feeders that remove plankton from the water, said Beth Bear, Game and Fish’s aquatic invasive species coordinator. That starves young and small fish and wreaks havoc throughout the food chain.

Now the agency has set its sights on invasive plants as well.

A regulation new this year requires all vegetation to be removed from boats when they leave the water, and all plugs removed while in transport. It’s hard to identify invasive plants, so the goal is keep any vegetation from moving to different bodies of water, she said. Keeping the plugs removed makes sure there isn’t any standing water left where invasive species could live undetected.

This year Yellowstone National Park banned felt-soled waders, “due to the urgent need to prevent these destructive species from entering the park,” a press release said, referring to aquatic invasive species. The park also created a boating season that runs May 26 through Nov. 4 to insure staff are on hand to inspect all watercraft — everything from cabin cruisers to float tubes.  

Wyoming hasn’t taken such extreme precautions, but is focused on inspections and awareness-building among boaters about the dangers of mussels.

Inspectors are looking for any organism that could move from one body of water to another, but the mussels are the biggest concern.

“Mussels are one of those invasive species that there is not a bad thing they won’t do,” Bear said. “There are few invasive species that can have the same kind of ecological impacts.”

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Game and Fish monitors 75 bodies of water in the state each year. So far they haven’t found signs of the mussels. But the discovery of the invasives in Montana was a reminder to stay vigilant.

“The threat is very much all around Wyoming,” Bear said. “It’s always bad news when we hear about mussels in nearby states. We don’t want them in Wyoming and we don’t want them in our neighboring states. It’s a western-wide fight.”

Only New Mexico, Idaho, Oregon, Washington, Hawaii, Alaska and Wyoming remain free of the invasive mussels, Bear said.

“All it takes is one boat,” she said.

Once mussels are introduced into a body of water, there is no way to eradicate them. Instead post-contamination efforts shift to containment and control. Bear isn’t sure if it’s possible to thwart the introduction of the mussels in the state forever.

“But every year we prevent them saves the state millions of dollars,” she said.

Each year that goes by also allows the science to advance. Bear hopes if mussels eventually make it into Wyoming, there will be a way to eradicate them.

Wyoming has a rapid response plan if mussels are found in the state’s water. The goal would be to leave water open to boating, but contain the mussels and prevent them from spreading, Bear said. It would call for increased monitoring and inspections at the boat ramps and decontamination of any boats on waters where the mussels were found. The one thing missing from the plan is funding. There isn’t money set aside if they need to activate the plan.

For now, Game and Fish is focused on prevention. Inspectors check about 42,000 boats a year at 15 permanent stations. Memorial Day weekend will be busy for boaters and inspectors alike at places like Boysen Reservoir and Flaming Gorge, but the busiest time for inspections is Fourth of July week.

Inspectors already have caught four mussel-contaminated boats this year, Bear said — three at the state’s port of entry near Cheyenne and one near Beaulah, coming from South Dakota. The offending vessels boats often come from the Great Lakes were there aren’t boat inspections, she said.

Mayton started as an inspector with Game and Fish’s program when it began in 2010. Since that time the public has gotten better about understanding the importance of inspections, he said. Most of the boats they check are following the “clean, drain and dry” rules, but each year inspectors find 10 to 20 boats with mussels. Most of the mussels they find are dead and have been for a while.

Standing water, not actual mussels, prompt the the majority of requisite decontaminations he said. Mussel larvae can live in standing water, undetected by the naked eye, for up to 30 days.

And once the make it into a waterway, their offspring can live forever.

Kelsey Dayton

Kelsey Dayton is a freelancer and the editor of Outdoors Unlimited, the magazine of the Outdoor Writers Association of America. She has worked as a reporter for the Gillette News-Record, Jackson Hole News&Guide...

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