Milfoil fight not yet over, experts say

Idaho is declaring victory after a massive, summerlong offensive against milfoil, but weed control experts say the state is far from wiping the exotic invader from lakes and rivers.

Tons and tons of the frond-leafed weed have been eradicated from North Idaho waterways, but many new beds have been discovered. Counties are now trying to develop long-term control strategies, even though there’s no clear funding source.

“Every time you’re out there you find more,” said David Lamb, lake ecologist for the Coeur d’Alene Tribe and chairman of the state’s milfoil task force. “I would not say we’ve turned the corner yet.”

The tribe treated 334 acres at the southern end of Lake Coeur d’Alene using a combination of herbicides and hand-pulling by divers. Many of the thickest mats of weeds appear to have died back, but Lamb said other patches of weeds treated by herbicides died back but later sprouted new growth. The toughest weeds appear to be a hybrid between native and exotic species of milfoil, Lamb said, adding that the species are tough to distinguish outside of a laboratory.

A tenacious, hybridized variety of milfoil will only further complicate the state’s push to pour millions into an all-out eradication effort. Idaho legislators had hoped that by funding an unprecedented $4 million milfoil control effort, a knockout punch could be delivered to the aquatic invader from Eurasia, which had established itself in some 7,000 acres of lake and river bottom over the past decade.

Lake lovers say the weed not only displaces native plants and destroys fish habitat, it can also form mats thick enough to entangle swimmers and smash the hulls of fast-moving boats.

Although the weed can be pulled, smothered or poisoned, experts say it’s tough to completely remove it from a waterway. Personal watercraft and boats help spread the plant by chopping its leaves – a tendril not much longer than an eyelash can sink to the mud and take root.

Much of this summer’s eradication efforts relied heavily on the use of chemical herbicides. A citizens group in Bonner County – where more than half of Idaho’s milfoil had been found – is calling on public officials to consider control efforts other than chemical carpet-bombing of weed beds.

Roughly 100 tons of chemicals were poured into Bonner County waterways, according to Steve Holt, a Sandpoint resident and member of the Panhandle Environmental League. Although county officials claim an 85 percent success rate in killing the weeds where the chemicals were used, Holt said his group’s surveys show a success rate in the 50 percent range.

Holt said the county has relied too heavily on chemicals, without trying out more long-term, environmentally friendly solutions, such as planting thousands of tiny weevils that eat milfoil or using sun-blocking mats to smother the weed.

“They didn’t ask for one penny for anything but herbicides,” Holt said, adding that many residents stayed away from beaches because of concerns over the chemicals. “It really took a toll on our summer scene.”

In Holt’s view the best hope lies in the milfoil-eating weevil, which have recently been found living in Lake Pend Oreille. A hatchery of sorts would be needed to raise enough additional weevils to make an impact on the weed, Holt said.

Bonner County Weed Supervisor Brad Bluemer said he’s open to the idea of the weevils but has yet to see proof they work. Bluemer also said the state has not approved their use, so the county is unable to spend state tax dollars on the insect.

“It’s the state’s money and the state’s gotta approve it,” he said. “We have weevils already here, and they’re not doing anything. Why spend more money on them?”

Bluemer said about 3,000 acres of milfoil were wiped out in Bonner County this summer, thanks to $1.7 million from the state. Another 1,000 acres of the weed remain. Bluemer is hopeful another summer of intensive control efforts – including the use of diver hand-pulling, sun-blocking mats and a planned boat wash station – will take care of most of what’s left.

“It definitely was a big turning spot, no doubt about that,” Bluemer said of this summer’s work. “It’s going to be considerably easier and a whole lot smaller of a project from here on out.”

In November, a third-party review of the eradication effort will be conducted by a group of experts from outside the state, said Idaho Rep. Eric Anderson, R-Priest Lake, who led the crusade to fund the war on milfoil. Anderson said he plans to ask for another $4 million for milfoil control during the next legislative session. Eventually, Anderson would like to see boaters fund a permanent invasive species control program through the purchase of a sticker, which would likely cost between $3 and $5, he said.

Apart from helping to round up the money, Anderson has been personally involved in the milfoil control effort. This summer, he personally dove to the bottom of Priest Lake to help pull nearly five acres of the weed.

“We’re going to win this one,” Anderson said.

Much of Kootenai County’s milfoil control work this summer focused on Hayden Lake. The weed was discovered growing on 750 acres in the lake in 1997. Until this summer, the county could only afford to remove between 85 and 100 acres, according to Nina Eckberg, the county weed superintendent.

This summer, nearly 300 acres in Hayden Lake were treated with herbicides. Another 12 acres of weeds were pulled by divers. Plastic barriers were also placed atop 1,400 square feet of the weeds. Eckberg estimates less than 100 acres of milfoil remains.

“I’m hoping we got the upper hand,” she said, adding that the true test of effectiveness won’t be known until late spring, when the warm sun returns and plants again begin sprouting from the muddy bottoms of lakes.

Much more milfoil eradication work remains to be done in the county, Eckberg said, including near the communities of Harrison and Bayview.