Eurasian Watermilfoil found in Kootenai River

By ROBERT JAMES

Managing Editor

A Boundary County official found Eurasian Watermilfoil, a very invasive and destructive aquatic plant, along nearly 100 miles of shoreline on the Kootenai River earlier this month, confirming that the noxious weed had spread into this county.

Apparently, the Eurasian Watermilfoil creeped into the Kootenai at least two years ago, where it lay undiscovered until the beginning of October, county weed superintendent Duke Guthrie said Tuesday.

Guthrie discovered the infestation after deciding to take advantage of the low river levels. He was shocked at the extent the weed has established itself here.

"It's pretty much all the way from Porthill back to the mouth of Deep Creek," he said.

It's the first official identification of Eurasian Watermilfoil in Boundary County, he said, and it immediately raises concern for the Kootenai National Wildlife Refuge, which uses water from Deep Creek and the Kootenai River in its wetlands.

The refuge will closely monitor the situation, and Guthrie was surveying the waterways within the refuge to determine if the noxious weed was present, refuge manager Dianna Ellis said. Guthrie did not find any evidence of the weed inside the refuge as of Tuesday.

The refuge will begin educating visitors about the plant immediately, she said.

Education is the key to slowing the spread of Eurasian Milfoil, which is related to northern milfoil, a native plant to this area.

The weed is spread largely because people do not clean off their boats and other watercraft after using them in an infested lake or river, Guthrie said.

When they put the boat in another body of water, the pieces of plants stuck to the craft break off and establish new milfoil colonies.

From there, the plant multiplies extremely fast.

"It wouldn't take long to entirely take over one of our small lakes," he said.

Treatment of milfoil is difficult and the circumstances surrounding the Kootenai River make control efforts nearly impossible.

Normally, either herbicide or barrier methods are used to halt milfoil's advancement.

The river's current makes barrier methods impractical and the fact that there is an ongoing fish recovery program in the river for sturgeon and bull trout complicates any use of chemical control, Guthrie said.

He hopes the river's natural current and the varying water levels will help control the outbreak.

Eurasian milfoil requires sunlight to grow and only grows at depths shallower than 12 feet, Guthrie said.

The sheer size of the outbreak, which covers nearly 100 miles of shoreline on both sides of the river, makes control a daunting task.

"The challenge in this river is it's pretty much the entire length from town into Canada," he said. Guthrie had not yet completed his survey of the river below the bridge in Bonners Ferry, either.

Guthrie urges everyone to thoroughly clean their water-going equipment, from outboard motors to inner tubes, to make sure no aquatic plants hitch a ride from one body of water to another. Anyone who thinks they have found Eurasion Watermilfoil in the county should bring a sample to the Boundary County Extension Office behind the courthouse, or call 267-5341 for more information.