An invasive weed in Mineral Lake threatens to tangle up boat motors, out-compete native species and impact critical habitat. Eurasian watermilfoil is a common pest in Washington state, and was first detected in Mineral lake last fall.
The good news is that the plant — one of the most problematic submerged weeds in the Pacific Northwest, according to the state Department of Ecology — is in its early stages in Mineral Lake, cropping up in patches around the shore.
Still, documents from Ecology warn that the spread of Eurasian watermilfoil downstream of Mineral Lake — to Alder Dam on the Nisqually River — “should be of great concern.” The stringy weed could “pose significant threats to the infrastructure of the dam.”
With financial help from the state, county officials hope to eradicate it before it causes major problems in Mineral Lake, the self-proclaimed “gem of the Northwest,” which allures locals and tourists alike. The county’s agreement with the state clocks the project at $90,000.
The fast-tracked process, according to Charles Edmonson, Lewis County Noxious Weed Control program coordinator, will hopefully mean quick results this summer.
Bellingham-based Aquatechnex will contract with Lewis County to apply florpyrauxifen-benzyl to the weeds, a relatively new chemical that causes the plant’s cells to elongate, eventually killing it. The aquatic species will produce longer, twisted leaves within hours, and then die off in coming weeks.
Fish die-offs can occur when large amounts of aquatic weeds die and decompose at once, but officials are confident the current infestation of Eurasian watermilfoil won’t have a major impact, since there isn’t a large amount of it.
Locals should know that the chemical is safe for humans, and the lake won’t be restricted to swimmers or boats while the chemical is being deployed.
And if Washingtonians want to do their part, Edmonson said they can learn to identify the plant. It spreads through plant fragments, meaning parts of the weed stuck to boats, kayaks or other items could serve to establish the weed in other parts of the region.
Recreationalists should take extra care to clean off their boats of any plant matter, Edmonson said.
If they don’t, it’s possible that the species could spread to high-elevation lakes within the Gifford Pinchot National Forest or Mount Rainier National Park.
“A final note would be that the (Ecology) grant is made possible and funded by registration fees for boats and trailers,” he wrote in an email. “The infestation of watermilfoil probably got in the lake from a plant fragment that wasn’t spotted and/or properly cleaned from a boat or other recreational equipment, so this seems particularly fitting.”
