News & Features

Mussel Infestation Could Cost Montana $234 Million Per Year

Report says recreation, infrastructure and irrigation would suffer if invasive species become established

Montana’s economy could see more than $230 million in annual mitigation costs and lost revenue if invasive mussels become established in the state, according to a report released Jan. 24 by the Montana Invasive Species Council (MISC).

Commissioned by MISC and completed by the University of Montana Flathead Biological Station, the economic impact study provides “a snapshot of projected direct costs to affected stakeholders dependent on water resources,” according to Bryce Christiaens, who chairs the MISC. “It does not reflect the total economic impact to the state, which would be considerably higher.”

The report identifies three key economic sectors — recreation, infrastructure and irrigation — that face the greatest potential impacts from an established mussel infestation, accounting for 60 to 75 percent of the total potential damages statewide.

“Invasive mussels can devastate aquatic ecosystems, clog water intake pipes and delivery systems, cover boat launches and beaches, and impact any economic sector dependent on water,” Christiaens said. “They pose a major threat to Montana’s environment, economy, recreation, and human health.”

Montana Fish, Wildlife and Parks has been working to prevent the introduction of invasive mussels since 2005 through watercraft inspection, early detection monitoring and education. Those efforts ramped up when invasive mussel larvae were detected at Tiber and Canyon Ferry reservoirs in 2016.

The detections led Gov. Steve Bullock to declare a natural resource emergency and form a joint mussel response team.

While mussels have not crossed over to Northwest Montana, officials from FWP, the Confederated Salish and Kootenai Tribes, Flathead Lake Biological Station, Glacier Park, MISC and other agencies have collaborated on an emergency response plan for the worst-case scenario.

Much like a wildfire, the event of an invasive mussel detection would warrant an immediate response from a long list of agencies working together to evaluate, strategize and organize resources to address the problem.

With additional funding from the Legislature, FWP was able to double their prevention efforts, triple early detection monitoring and expand education to the public. To date, no adult mussels have been found and no additional invasive mussel larvae has been detected since the initial detection in 2016.

“Eradicating invasive mussels once they establish is difficult if not impossible,” Thomas Woolf, FWP aquatic invasive species bureau chief, said. “Prevention is our best bet at keeping them out of our waters and avoiding the costs associated with their impacts. Research continues on methods to prevent and manage mussels, so the longer we can keep them out, the better the chances we’ll see a solution to this problem.”

The study was commissioned to provide managers and policy makers with an estimate of costs in order to inform decisions about the level of funding for state prevention and containment programs. The current level of Montana’s AIS funding, approximately $6.5 million, is roughly 3 percent of the estimated $234 million annual costs for invasive mussel mitigation and lost revenue.

The MISC is a statewide partnership working to protect Montana’s economy, natural resources, and public health through a coordinated approach to combat invasive species. For more information about MISC and to access the report, visit

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