Local commission pushing to stop spread of invasive mussels

YELLOW BAY – A group tasked with protecting the aquatic resources of the Flathead River drainage is urging state officials to close the Canyon Ferry and Tiber reservoirs to all boats as evidence mounts that both of the Central Montana water bodies now harbor invasive mussels. The Flathead Basin Commission is including the closure recommendations in a letter to Gov. Steve Bullock, drafted last week at the University of Montana’s Flathead Lake Biological Station. It was the commission’s first meeting after the Department of Fish, Wildlife and Parks’ Nov. 9 announcement that the long-feared presence of invasive mussels had been confirmed in Tiber Reservoir — the first such detection in the state. Glacier National Park and the Blackfeet Nation both closed all their waters to boating within days of the state’s announcement and the U.S. Fish and Wildlife Service followed suit by closing a popular recreation pond that supplies water to its hatchery in Creston. While the commission’s letter is not yet finalized, the group agreed to ask Bullock to initiate the closure of Tiber and Canyon Ferry Reservoir, where mussels were detected last month but not positively confirmed. Executive director Caryn Miske said Friday that surveys this week at Canyon Ferry have lent more credence to the likelihood — but not the certainty — of invasive mussel contamination in that reservoir, as well. “As a whole, there is a feeling that we’re going to need to do significantly more than we’ve done in the past, if we’re fortunate enough that they haven’t invaded the Flathead yet,” Miske said. “We know at some point we’re going to have to put in a containment effort related to those waters, and if other waters have been contaminated.” For now, invasive mussels have still never been detected anywhere west of the Continental Divide in Montana. But the status of Canyon Ferry and Flathead Lake — separated by about a 200-mile drive — as the two most popular boating areas in the state has alarmed commission members. “If we’re not infested, it’s just a matter of having been lucky,” said Thom Smith, the commission chairman. He added, “We all have to say we’ve failed and we’re going to have to change if we’re going to have a reasonable chance of protecting this incredible resource we’re all entrusted with.” This spring, the commission began using a team of dogs specially trained to detect invasive mussels at its boat-check stations in and around the Flathead basin. Along with mussel dogs from Alberta, the teams are currently searching any adult mussels that would indicate the presence of a reproductive population. Miske said Friday that the dogs had sent a strong signal that Canyon Ferry has been infested as well. “That all the dogs alerted at one particular boat at one spot in Canyon Ferry, what they were likely sniffing is the secretion left behind by a mussel,” Miske said. But, she added, “Did the dogs confirm whether there was an adult mussel present? No.” Fish, Wildlife and Parks spokesman Ron Aasheim also said Friday that the dogs had alerted to “hot spots” along Canyon Ferry’s shore, where some form of invasive mussel presence was possible, but the agency has yet to confirm any contamination with visual or DNA evidence. Per the state’s “rapid-response plan,” an inter-agency task force is working on a plan to respond to and contain the mussel introduction. Aasheim said that while the option to close the reservoirs to boating is still on the table, it is not one the team is actively pursuing. “At this point, we’ve talked about it and there are no plans (to close them) right now,” he said. “We understand there are people, including the park and the Blackfeet, that have made that decision, but the experts we’ve talked to have said that’s not the best decision.” With water temperatures dropping, Aasheim noted that free-floating mussel larvae, such as those found in the positive samples taken from last summer, are increasingly unlikely to persist in the water column. He also noted that boating season has largely wound down for the year. Miske said that choosing not to close Canyon Ferry, in particular, could lead to a mussel-fouled boat launching elsewhere.

“In Canyon Ferry, you do have moored boats. When boats sit in the water, the chances of mussels attaching becomes greater and greater,” Miske said. “I’m sure some of the boats have already been pulled out of the water, and we don’t know where those boats are going. ... At the very least, having an exit strategy for decontamination is important.” Should the agency opt for boating closures, their request would require approval by the Montana Fish and Wildlife Commission. State officials are also looking into the possible draw-down of Tiber Reservoir to kill off any mussels, but Aasheim said that would require extensive coordination with hydropower, irrigation and angling stakeholders. In the meantime, he said the state is continuing to deploy mussel dogs and snorkelers along the shorelines to search for adult mussels. No adults have been found, raising at least a slim possibility that a reproducing mussel population has yet to become established in either water body. Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.