Aquatic Invasive Mussel Species in Montana


An ecological disaster landed in Montana last November, when tests confirmed the existence of invasive Quagga mussels in the Tiber Reservoir, 80 miles north of Great Falls.

Department of Natural Resources officials discovered mussel larvae through water testing in Tiber and an inconclusive, but possible infestation in the Canyon Ferry Reservoir, east of Helena, as well.

After initial tests came back, DNR officials used specially trained dogs to help detect adult populations of mussels in both reservoirs. No adult populations were found, but the dogs did indicate populations were present.

The mussels present a serious ecological and economic threat to Montana. It’s another chapter of an invasive nightmare, which has decimated native fish populations and damaged dams and other aquatic infrastructure, across the country.

Park officials said the situation is so dire, Glacier National Park immediately closed its borders to all watercrafts last November and will remain closed to all motorized watercraft coming into the park for the year. Hand-powered watercraft will still be allowed, however, they will be subject to inspection stations at four different areas of the park Park.

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Jeni Flatow, Montana’s mussel response public information officer, said even though adult mussels weren’t found, the reservoirs are being treated as if they are infected. Flatow said winter made finding adult mussels difficult because of the frozen reservoirs. However, the ice did help control the mussels, because adults won’t breed during winter and the lower water levels may have exposed the adults to the cold air, which can kill them.

Flatow said the next steps are setting up more watercraft inspections, and decontamination stations while finding, controlling, and containing any adult populations. Options for controlling the mussels are limited. Flatow said they can either draw water out of the reservoir, or try a chemical option.

According to David Brooks, Associate Director of Conservation for Montana Trout Unlimited, neither method is without flaws.

Brooks said drawing out water has never eradicated a whole population and can have devastating effects on river habitat downstream, as well as irrigation use. The chemical options could kill native species, however.

The Army Corps of Engineers has experimented with a chemical called Zequanox. According to Brooks, the chemical has, so far, been shown to kill mussel populations while not harming native species.

Brooks said the only issue with Zequanox, however, is the size of Tiber Reservoir. The adult populations would need to be targeted, or enormous amounts of the chemical would need to be applied.

Containment will be of the highest priority, but a difficult one as well Brooks said.


Where Did They Come From?

Zebra and Quagga mussels are native to Eastern Europe and were brought to North America through the ballast water in ocean ships traveling through the Great Lakes.

The mussels were discovered in all the Great Lakes by 1990 and have made it to almost half of all the states by attaching to boat hulls and propellers, or surviving in bilges and live wells.

The mussels filter-feed phytoplankton out of the water and, with no competitors, will decimate the microorganisms, negatively affecting every other species. The water will become crystal clear, after all phytoplankton is gone, allowing more sunlight to reach the bottom of the water, which can also cause unnatural algae blooms.

The algae bloom concentrate bacteria and have been linked to botulism outbreaks, creating an unsafe, or even deadly, swimming environment.

The mussels are heavily responsible for the collapse of fisheries in the Great Lakes, as well. According to government data, Lake Michigan alone has an estimated half a billion pounds of mussels wreaking havoc on the ecosystem.

This is foreboding news when it comes to Montana’s native trout populations and Montana’s economy, which relies heavily on native trout populations

According to Brooks, Montana sold over 400 thousand fishing licenses in 2016 and made nearly 343 million dollars from licenses, guides, tackle, and more. The Smith River alone made close to $10 million, he said.

Brooks said tourists who fish in Montana are likely to spend twice as much time visiting the state and twice as much money.

“When people think of Montana, they think of trout streams,” Brooks said. “This is what Montana is known for.”

Outdoor recreation isn’t the only industry stepping up to combat the mussels, either. According to Brooks, hydro-powered energy companies may provide grants to fight the invasion. Because of the mussel’s tendency to grow on dam turbines and clog irrigation pipes, companies like NorthWestern Energy, as well as their customers, have a lot invested in fighting the mussels.

Brooks said if the energy companies are forced to clean turbines, energy rates will likely go up and affect Montanans, even if they don’t fish. He added that now it’s more important for all Montanans to properly dry their boats, use the check stations and drain all the water from them, whether a person owns a rubber raft or a powerboat. He even recommends using a heated pressure washer, if able, to spray down the hull of the boat and empty the ballast tanks and live wells before entering another body of water.

“You may not own stock, but you pay rates,” Brooks said. “Your clean boat can help save power costs for everybody.”

To help boaters prevent a further spread, Fish Wildlife and Parks are providing decontamination stations across the state.

Looking Forward

Montana waged a long war against the introduction of the mussels, but the massive cross-country spread starting in the 90s made their introduction to the state more when than if.

“People saw it coming,” Brooks said. “It’s the new norm.”

The discovery of mussels in Montana has the potential to be a bombshell, not just for Montanans, but for the rest of the country as well. Montana, specifically the Glacier National Park area, is critical to keep invasives out of because of the major watersheds leading to the Pacific, The Hudson Bay, and the Gulf of Mexico.

If Flathead Lake -the largest freshwater lake west of the Mississippi – is exposed, there will be very little to prevent the species from getting into the Columbia River downstream. Once in the Columbia, the mussels could have devastating effects on already vulnerable salmon runs and the over 60 hydroelectric dams found in the watershed.

Decontamination stations and the old adage of “clean, drain, dry” are still important, but it’s no longer enough to keep the mussels from further spreading, said Caryn Miske, the executive director of the Flathead Basin Commission.

Because Tiber and Canyon Ferry feed into the Missouri River, Miske said the entire system should be considered contaminated, making it imperative to keep the spread from crossing the Continental Divide.

She said boats need to pick a body of water and only recreate there to prevent the crisis from getting worse. The Blackfeet Tribe has even gone to the length of banning motorized watercraft from all but four tribal lakes.

“Clean, drain, dry was the mantra, but now it’s no lake hopping,” Miske said.

The suggestion may sound extreme, but Miske said inconveniences like no lake hopping, or stopping at a boat check station, are better than further exposing a financial problem in the hundreds of millions, and an environmental problem she referred to as “ecological armageddon.”

“We have to act now and it has to be serious,” she said. “Maybe in six years we can find a cure, so every year we keep it out, it’s buying us time.”

Updated August, 2018

Written by Scott Mathson