Efforts to contain AIS in Beaver Lake find success

Efforts to contain and eradicate an aquatic invasive species from Beaver Lake so far have proven successful.

Montana Department of Natural Resources and Conservation in October 2011 discovered Eurasian watermilfoil near the boat ramp at Beaver Lake west of Whitefish. Eurasian watermilfoil is an aquatic plant that grows in still or slow-moving water. If left untreated, it can form dense vegetation mats on the water, which can threaten the health of the affected water body and interfere with recreational activities like fishing, swimming and boating. Property values for lakefront homes can also be negatively impacted by an infestation.

After the discovery of the milfoil, an AIS response group, which includes Whitefish Lake Institute, placed bottom barriers over the identified patch of milfoil and developed a control and eradication plan with the city of Whitefish, WLI director Mike Koopal said.

In 2012, 23.5 pounds of the plant was removed from Beaver Lake through a suction dredging operation, and by 2016 milfoil had only a very small presence in the lake. Last year less than a quarter of a pound of milfoil was removed from five plants in the lake.

“We’re down to just one or two individual plants per year that we’re sucking out of there, so that’s a success,” Koopal said.

Koopal said this success story is atypical of AIS infestations, where such thorough treatment is rarely the reality.

Very early detection and aggressive eradication techniques helped make Beaver Lake the exception, Koopal said, and suction dredging will continue until the institute is sure milfoil is eradicated.

Full eradication is especially important because of Beaver Lake’s proximity to Whitefish Lake, Koopal said.

“Beaver Lake is hydrologically connected to Whitefish Lake and it’s only a quarter mile flight for a duck with some watermilfoil wrapped around its leg to land in Whitefish Lake,” Koopal said. “Then we have a big problem.”