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Discovery of invasive mussels keep Montana’s boat inspections busy

AIS boat inspections FWP
Posted at 4:46 PM, Apr 21, 2021
and last updated 2021-04-21 18:46:31-04

MISSOULA — Only a few weeks into the season, Montana check stations have already stopped about 10 boats with invasive mussels attached. It’s going to be another busy summer, and more people may be passing through at night bringing invasive species with them.

On Saturday, Fish, Wildlife & Parks watercraft inspectors at the Anaconda station were busy checking all the boats being towed along Interstate 90 when a large sailboat came in. It had come from Lake Michigan in Wisconsin, and dead mussels were found covering the hull and propeller. The boat was headed for Washington state, so inspectors decontaminated the boat and informed the next check station.

On Sunday, another Wisconsin craft headed for Washington, a pontoon boat, was found to have mussels in the live-well pump. Even more concerning, mussels were then found on a Minnesota pontoon boat headed for Glacier National Park.

The Anaconda crew had already stopped two infested boats during late March, one from Wisconsin and the other from Michigan. On April 10, inspectors found dry and dead mussels on a used pontoon boat purchased in Minnesota that was destined for Washington state.

The inspection stations at Wibaux and Hardin on Montana’s eastern borders should stop these boats coming in from the Great Lakes. So how are so many making it all the way to Anaconda?

Part of it has to do with inspection station hours of operation, said Zach Crete, FWP Aquatic Invasive Species Prevention Coordinator. The Wibaux station is open from 7 a.m. to 7 p.m. Anyone traveling through Wibaux at night slips by, but it will often be daylight by the time they reach Anaconda.

It’s also a matter of what date the stations become operational. The Anaconda, Dillon and Ravalli check stations open the earliest in mid-March. They are the last line of defense around western Montana and Flathead Lake.

The Wibaux station didn’t open until April 10. The 20 remaining stations will open between now and Memorial Day.

Crete said the Aquatic Invasive Species program staff knows boats entering the state during the night could pose a problem. So they’re looking into trying a pilot project at the Hardin inspection station to test the possibility of running a station at night. The busiest time of the summer happens around July 4, so that week would provide the most data.

“There are some significant challenges with law enforcement. We would want law enforcement to be present,” Crete said. “We’re hopeful we can pull something together to at least get an idea of what night traffic looks like on that corridor.”

The Confederated Salish and Kootenai Tribes operate the Ravalli station north of Missoula 24 hours a day. Crete said they check a few hundred boats a year at night. This year, the Ravalli station has already checked about 800 boats in the past month. That’s good because Flathead Lake and other tributaries of the Clark Fork River need to stay clean.

Zebra and quagga mussels first showed up in the Great Lakes in 1991 after being brought in by boats from Asia. They’ve spread since then, carried by boats to other lakes and streams of the U.S.

The Columbia River basin, which includes western Montana, northern Idaho and Washington, is the last area in the U.S. that hasn’t been invaded with invasive mussels. Regional leaders would like to keep it that way because the dime-sized mussels can multiply to encrust everything from beaches and boat ramps to irrigation pipes and hydroelectric turbines.

Since 2016, when a few mussel larvae were found in water samples from Tiber Reservoir and Canyon Ferry, the state of Montana has ramped up inspection efforts to avoid infestation. Prevention is cheaper than control efforts. While it costs the state about $5 million each biennium to run its Aquatic Invasive Species program, that’s nothing compared to the hundreds of millions other states spend every year trying to beat back the nonnative bivalves.

This year, two bills have passed that strengthen laws aimed at preventing mussel invasions. One requires boats from infested waters to pull their drain plugs. The other requires a boat to be decontaminated unless it’s been out of the water for 45 days.

But some Republican legislators tried to undercut the program. Sen. Theresa Manzella, R-Hamilton, sponsored a bill that removed hydroelectric dam operators from the list of those paying into prevention efforts. The Legislative fiscal note concluded that would result in slashing the AIS budget by a third.

Fortunately, Manzella’s bill died, because Montana’s investment appears to be paying off – it’s remained mussel-free for the past five years. But some worry it’s just a matter of time.

Crete said all of Montana’s watercraft inspection stations are seeing increased traffic compared to this time last year. In addition to the Great Lakes, many boats come to Montana from the infested waters of Lake Mohave, Lake Powell and Lake Havasu in the southwestern U.S. So far, the Dillon station has stopped two Arizona boats that were carrying mussels.

“In just one day, mussels can enter a live-well or attach to a boat’s hull or transom,” said AIS Bureau Chief Tom Woolf. “Always to be sure your boat is clean, drained and dry when leaving the water.”