In most places, Kootenai County Weed Superintended Nina Eckberg found just what she was looking for as she stared into the blue-green depths of Hayden Lake.
“It was here last year,” Eckberg said, while conducting a methodical, bay-by-bay search for eurasian milfoil.
The weed was first found in the lake five years ago. Since then, herbicides have been used and nearly 200,000 pounds of milfoil have been hand-pulled from the lake’s sandy bottom. But the weed is resilient and tight budgets allow for only a portion of the lake to be treated each year. That’s why Eckberg was cruising the lake in a boat this week looking for the thickest stands.
“If we’re doing anything, we’re making headway very, very slowly,” she said. “It’s a real difficult situation.”
That’s the best that can be hoped for in the case of lakes and rivers infested with milfoil, Eckberg said. Although only a handful of water bodies in North Idaho are home to the weed — notably Spirit Lake, Hayden Lake and Lake Pend Oreille — Washington is home to at least 107 lakes and rivers with milfoil, according to the state’s Department of Ecology.
The pernicious plant has no natural enemies here and can quickly overtake native aquatic plants. This ruins fish habitat, clogs water intake pipes and decomposing biomass from the fast-growing weed can starve a lake of precious oxygen. Swimmers can also become entangled in the weed’s long, feathery fronds.
Basically, milfoil gunks up a lake.
But the weed is no weakling. All it takes to spread the plant is for a fragment to become stuck on a propeller and taken to a virgin waterbody.
Short of a total ban on boating and a massive infusion of cash, the weed will probably always grow in local lakes, Eckberg said. But milfoil can be kept under control with herbicides or hand-pulling by scuba divers. That’s why Eckberg and a colleague were motoring around Hayden Lake searching each bay and stretch of shallow shoreline for signs of the weed.
Many areas along the south shore were clear of milfoil. But the scene changed when the boat floated over shallower, northern reaches of the lake. Dave Klaw, a county weed specialist at the helm of the boat, pointed out a vibrant underwater garden growing in McCleans Bay.
“This is quite a stand,” he said, peering over the gunwale. “Looks like an old growth forest down there.”
The location was marked with a global positioning unit. It was one of at least 20 stands of milfoil identified in during the weed survey. Next Wednesday and Thursday, herbicides will be injected into about 80 acres of the densest stands. Scuba divers (at $65 per hour) will then hand-pull weeds from the thinner patches. The weeds will be sucked up hoses and gathered on a barge to prevent fragments from spreading to other parts of the lake.
About 500 acres of Hayden Lake — roughly 15 percent — is infested with milfoil, Eckberg said. State permits and limited budgets restrict the acreage that can be treated with herbicide. The entire project cost is $80,000, a quarter of which is paid by the county. State and federal agencies and a small amount of private donations cover the rest.
The weed also grows in Spirit Lake, but an ambitious eradication effort funded largely by property owners has reclaimed all but about 10 acres in the lake, Eckberg said. There have been unofficial reports of milfoil in Hauser and Twin lakes, but the county has had neither the time nor manpower yet to survey the lakes. The county also is hoping to survey Lake Coeur d’Alene for milfoil, Eckberg said. The lake’s depth and dropoffs offer some protection from the weed, which typically grows in brighter, shallower waters.
Liberty Lake will apply herbicides to weedy areas in early July, said BiJay Adams, lake manager for the Liberty Lake Sewer and Water District. Divers will also be used. The Washington Department of Ecology recently awarded the lake $100,000 to fight milfoil over the next five years.
“We’re having good water clarity this year so the growth of milfoil will also probably be good,” Adams said, adding that aggressive control efforts last year have kept the weed under control. “Eradication is our overall goal, but it would be so difficult.”
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