During the hottest part of a nine-hour shift at the Wyoming Game and Fish Department’s Frannie boat inspection station, Aquatic Invasive Species (AIS) Specialist Emily Youse, in her long-sleeve red shirt, was having a busy Sunday. Earlier that morning she found four zebra mussels on a boat, not exactly a rare occurrence anymore.

“It's not often, but we do get some every year. They're all dead,” she said of the four in her hand. “The boat had been out of the water for three years; so these aren’t viable. But they can cause a panic.”

The four small mussels point to the necessity of the state’s fight to stay AIS-free.

Youse is part of the state’s team on the front lines of the fight against zebra and quagga mussels, as well as some invasive plants and animals like curly pondweed, which Wyoming does have, to species the state has managed to keep out, like Asian carp.

A full invasion could cost a state — dependent on snowmelt, canals and irrigation — millions in taxpayer dollars should the state not be ever-vigilant. Alaska, Hawaii, Washington, Oregon and Wyoming are the only states to remain free of these invasive mussels.

A female zebra mussel can release up to 1 million eggs each season so transporting just one zebra mussel can spell disaster. Invasive mussels are one of the most destructive types of AIS and it is very unlikely to eradicate mussels once they are established in natural water, the department reported.

The state has aggressive public information signage crossing the interstate systems, warning that boats must carry the state’s AIS decal, along with a yearly fee, and be inspected each and every time they travel by an inspection station with a boat in tow. The inspections are usually short — unless invasive species are found and/or the boat is in need of further cleaning with hot, decontaminating water. The Cody Region office has a special bay for inspecting and cleaning boats.

Wyoming faced an increased risk from aquatic invasive species last year, yet remains free of invasive mussels. Over the inspection season, Game and Fish staff at watercraft check stations inspected more than 73,000 boats across the state. Of the thousands of watercraft inspected, employees decontaminated 1,154 watercraft; 64 of those contained mussels — both the highest since the AIS program was established in 2010 by the Wyoming State Legislature. 

Youse said mussels can “really clog up systems,” during a short break in the action.

“They have what are called byssal threads and can attach to pretty much any hard or semi-hard surface. Think pipes, concrete, and in any water delivery system they can attach and clog up the systems. They can be pretty detrimental,” she said.

Lake Powell, in Utah and Arizona, is a great example. They have quagga muscles and the state spends “a ton” of money every year cleaning off the hydropower systems, Youse said.

“If you do irrigation, if you get city water, mussels getting into those systems will cost other water users and it's more expensive for the people delivering the water,” she said.

The state has responded with more check stations, including new operations in Manville and Newcastle. Game and Fish also has private inspectors across the state who will respond to calls from boaters needing inspections after hours. The list of inspectors can be found on the department’s website.

“If people are coming through late at night or during weird hours, they can call a private inspector and get inspected that way too,” Youse said.

There are several private inspectors listed in the Cody Region and across the state. Be prepared to tell an inspector where the boat is coming from, the last water it was in and how long since the boat was in the water so the inspector can understand the risks involved in the inspection process.

“If a boat is coming from the Midwest or Lake Powell, we want to know that. And that's because those veligers [final larval stage] and adult mussels can live for up to 30 days on a boat,” she said.

It is illegal to use a boat in Wyoming waters without a receipt from your inspection. Inspectors check the hull, motors, dry wells, anchors and other areas where the mussles can hide. The department has also previously deployed mussel smelling dogs to assist in the efforts.

“We’re making sure that the boats are clean, drained and dry,” she said.

On occasion motorists carrying or towing boats blow by the checks. Inspectors aren’t law enforcement agents, so they’re not going to chase you down. Instead, law enforcement is contacted with a description of the vehicle and watercraft. Police can write in a ticket or issue a warning. Either way, the motorist is sent back to the inspection station immediately.

Youse, who has a degree in terrestrial wildlife biology, does more than simply inspect boats. Among other duties, Youse has 21 waterways on her list to inspect several times a year for veligers or evidence of AIS between the Cody Region and Lander. She uses a fine mesh net, casting into waters around high use areas like beaches and boat ramps.

She also does shoreline sampling, looking for adult mussels that might be attached to rocks or plants and other AIS like curly-leaf pondweed.

“Every time you leave the water make sure your plugs are out, your live wells and ballast tanks are drained and clean off any plants you see. If you see anything that is kind of a concern. Give us a call,” she said. “We do our best to make it accommodating for the boaters and help them out as best we can.”