A task force of government agencies has formed to tackle and track the progress of an effort to eradicate a troublesome aquatic weed that has appeared in the Jefferson River near Three Forks, a Gallatin County weed specialist said.
The noxious weed, Eurasian watermilfoil, has been found in several spots around Montana. And now, the invasive weed has been detected upstream from Toston Dam, where it is established at a popular fishing access near Three Forks, said Gallatin County Weed assistant coordinator Michael Jones, a task force member.
“It was found last year at the Druillard fishing access in the high-water channels,” he said. “It’s also been found as far upstream as Cardwell. So, it’s pretty high up in the Jefferson River.”
Milfoil is also in the Missouri River down to the Cottonwood Slough in “several spots” and has been sighted at the Fairweather fishing access site at Clakston, though the report is not yet confirmed, Jones said.
The scourge was first detected in the Missouri River drainage at Fort Peck Dam and Toston Dam last year, according to the Montana departments of Agriculture and Fish, Wildlife and Parks. Milfoil has also been found in Noxon Reservoir near the Idaho state line in the northwestern part of the state.
The task force is just getting off the ground and the current goal is to start mapping the Jefferson River to determine the extent of the problem, Jones said. While the plant has not been reported in the Madison River, the blue-ribbon waterway will be included in the mapping process.
“It makes more sense to survey and find out how far upstream it is and work your way down,” he said.
Milfoil spreads easily, according to the 2002 Montana Aquatic Nuisance Species Management Plan. When the plant breaks up, pieces float downstream and each piece can establish itself.
“A single segment of stem and leaves can take root and form a new colony,” according to the state plan. “Once the plant is established it is almost impossible to eradicate it.”
The major way the invasive plant is spread is by boats, particularly motor and jet boats, Jones said. Since it takes so little plant material to establish, the weed can hide out on boats, trailers and vehicles and start new in an unaffected waterway.
There are some who believe waterfowl can spread milfoil, but not everyone is convinced, Jones said. That adds to the mystery as to how the plant appeared in the Jefferson River in the first place.
“The jury is still out if waterfowl can spread it or not,” he said. “It would take a fairly big fragment to get stuck on a duck. It is possible, but not real likely.