Game and Fish taking measures against zebra mussels
September 29, 2022
BUFFALO — Wyoming Game and Fish Department officials are increasingly concerned about the discovery of adult zebra mussels in Pactola Reservoir, a body of water just 20 air miles away from the state line in South Dakota’s Black Hills.
To mitigate the risk of contamination in Wyoming’s waters, the department will decontaminate all watercraft that have been used in South Dakota within 30 days of crossing the border.
During the decontamination process, according to the department, the inspector sprays the interior and flushes the interior compartments with scalding water to kill aquatic invasive species, followed by another inspection to ensure that the process was successful.
It takes much longer than a typical inspection, fisheries chief Alan Osterland told the Wyoming Game and Fish Commission at its meeting in Buffalo on Sept. 13. And he anticipates decontaminating more than 300 to 400 watercraft at the Beulah check station alone.
The department’s previous policy applied to boats coming from waters known to be infested with zebra or quagga mussels (another invasive species).
“We anticipate more waters in the Black Hills to be (contaminated) in the future,” Osterland said. “This is one reservoir in this chain of reservoirs.”
The invasive species was discovered in July, when two spear fishermen reported to South Dakota’s Game, Fish, and Parks Department that they found the mussels attached to a pair of sunglasses, Osterland said. So far, there have been two detections of adults in that water body.
Zebra mussels have not been found in Wyoming, as of press time.
“We’re going to have to consider some drastic measures,” Brian Nesvik, director of Game and Fish, said at the commission meeting. “Restrictions that are uncomfortable are going to have to be necessary. There are some people who are not going to be happy with some of the things we’re going to have to do.”
Zebra mussels are fingernail-sized bivalves native to Eurasia. They can prevent native species from moving, feeding, reproducing or regulating water properly, according to the National Park Service.
“We cannot allow this stuff to come across our eastern border,” Nesvik said. “We have to do everything we can to prevent it.”
There is no hydraulic connection between Pactola and Wyoming waterbodies.
Watercraft are the primary mode of transport for the species.
The mussels have been migrating the Missouri River and making their way into different water bodies in South Dakota, Osterland said. Pactola is the farthest west they’ve been found so far.
Game and Fish boat check data shows that a lot of boats travel west from areas in and around the Black Hills.
Since January 2021, Game and Fish has inspected 174 boats coming from Pactola. Keyhole Reservoir has been the primary destination for those, with 74, and Lake DeSmet has had six. Boats in Pactola Reservoir come from all over the country, which makes watercraft a vehicle to carry the invasive species.
Near Newcastle, LAK Reservoir has been closed to all watercraft as a precaution. The agency has also increased its AIS sampling and staff hours at inspection stations near LAK and at Keyhole Reservoir near Gillette.
“As of today, we haven’t gotten any information back that show any findings,” Osterland said.
The department is coordinating with South Dakota, other surrounding states and federal agencies. South Dakota lacks resources, both financial and manpower, so the U.S. Forest Service is sending personnel to help, Osterland said.
Staffing issues in remote locations like Beulah are a challenge for Wyoming Game and Fish, too, Osterland said.
He said that it’s likely the agency will have to consider options to make the job more appealing. Now that summer is coming to an end, officials are considering precautions and possible restrictions for next year in light of the infestation in Pactola.
Next year, there might need to be an inspection station at LAK.
“It’s a pretty straight shot on the southern route from Rapid City to LAK,” Osterland said.
And the restrictions that Game and Fish may have to put in place could be significant, Nesvik said, though he wasn’t specific about what they might be. One form of AIS prevention, though, is educating the public about how it can mitigate risk.
“Most people want to do the right thing,” Nesvik said. “They don’t want to be the per - son who brought something bad to our state — but it only takes one.”