Herbicide issue has muddied the waters

She's spent most of her 57 years at this watery jewel in rural King County. Gray-haired and fit, she lives in her childhood home, nestled among giant firs and cedars. She knows the lake well enough to recognize the calls of individual Canada geese.


		Gilbert W. Arias / P-I
	Caren Adams heads to her boat dock on Spring Lake in Maple Valley. Adams and other lakeside residents have joined King County in an effort to control the weeds that are squeezing out native plants in the lake.

She also knows the lake has a growing problem.

Over the years, invasive weeds have taken root -- creeping across the bottom, ringing the shore, squeezing out native plants. To combat the menace, herbicides will be sprayed at the lake, starting this week.

"Exotic weeds create some dilemmas that take more complicated thought," Adams said. "Doing nothing is not an option."

It's not an option at Lake Sammamish, either, where some residents are taking a no-herbicide stand.

"We are spraying toxic chemicals into the lake," said one of the concerned homeowners, Frank Lill. "Although the state approves it, who knows what effect it can have on children swimming in the lake or pets drinking the water?"

Across Washington, property owners, swimmers and boaters are peering into their favorite lakes and rivers to find invasive plants taking over. Water weeds are spreading each year, and new, troublesome varieties keep popping up, experts say.

The solution, however, is murky.

"It's becoming a really, really big issue," said Kathy Hamel, aquatic plant specialist with the state Department of Ecology. "It's worldwide."

Worried about how herbicides might hurt his seven grandkids, Lill grabs a rake and pulls the weeds from his shoreline property every summer. On his dock he heaps a soggy pile of Eurasian milfoil, a feathery weed that can tangle up people, boat propellers and fishing lines.

There are various strategies for battling milfoil and other weeds, but none are permanent or 100 percent effective.

State and county officials say the problem is best tackled on a lake-by-lake basis. For small lakes with limited infestations, hand-pulling and mechanical removal efforts can be effective.

When the weeds carpet a waterway, or in places where boats regularly carry stowaway weeds that reignite infestations, herbicides are the cheapest alternative.

The state permits the use of aquatic herbicides, but after two years lake communities are required to come up with a plan that also incorporates non-chemical controls. That rule also applies to individuals.

"Obviously, these chemicals are not going to be right in front of their homes," Hamel said. "They're going to drift."

She urged spray-minded residents to "work with their neighbors" to make sure everyone is safe.

This year, applicators received permits to treat more than 1,000 lake and river acres statewide. More than 250 acres are in Lake Washington alone. The state recently started to track herbicide use by acre, so it's unclear whether the numbers are on the rise.

"The concerns with the herbicides are pretty straightforward," said Angela Storey of the Washington Toxics Coalition, which opposes pesticide use. "They pose pretty significant hazards not only to people but to salmon."

Juvenile chinook migrate along lake beaches en route to the sea. The herbicide sprays are timed to reduce the likelihood of exposing fish to the chemicals, but there are no guarantees.

Spring Lake residents spent 18 months working with King County officials on their weed-control plan. They weighed all the options before coming up with a plan for their 68-acre lake, settling on a seven-year plan that relies on a broad herbicide application this year, followed by spot spraying and hand-pulling.

At the lake's lone public boat launch, sediment will be blanketed with a fabric that smothers weeds and blocks sunlight. The project is funded primarily by a $65,000 state grant.

This week, an aquatic herbicide applicator is scheduled to motor onto the lake and spray 2,4-D into the water to kill the tenacious milfoil.

Fragrant water lilies -- another invader -- will be individually sprayed with glyphosate, the active ingredient in Roundup and Rodeo. Along the shore, purple loosestrife and yellow flag iris also will be doused with glyphosate.

The weeds "all threaten the quality of the lake environment," Adams said. "The boating, the swimming, the wildlife diversity that we love."

The form of 2,4-D used at Spring Lake has a low toxicity for fish and water birds. At very high levels, the herbicide can be toxic to dogs.

Glyphosate has low toxicity for fish and mammals. It's slightly toxic to birds and aquatic bugs, and can remain for months in the sediment. Both chemicals are an eye irritant.

The Spring Lake plan is to use the herbicides in a controlled manner to prevent killing native plants.

"We didn't want to zap everything," Adams said.

Natural predators to milfoil remain elusive.

Researchers here and elsewhere have been studying a weevil that munches the weeds. But it's been tough to grow the bugs into large enough populations to have an effect. Sunfish -- another non-native species -- are suspected of gobbling them up.

There are also problems with some of the non-herbicide controls. The sediment fabric kills native plants, too, and it needs to be maintained or will be buried and rendered useless. It covers cobbles that could provide spawning habitat for fish.

Pulling the milfoil can break bits off that help the plant spread.

But Lill and others would rather work a little harder and settle for some of the tradeoffs than add chemicals to the lake.

As vice president of Save Lake Sammamish, Lill is also concerned about the effect of the dead weeds on water quality. The rotting vegetation can release nutrients, feeding algal blooms.

"Spraying with an herbicide does not get rid of it permanently. You're going to be out there doing something every year," said Lill, a retiree who's been a year-round lake resident for nearly 30 years.

Through postcards and e-mails, he's urged neighbors to rake or pay divers to pull the weeds. At least six are still opting for herbicides.

"We're asking people to do it the safe way," he said. "It's a bother, no doubt about that."

P-I reporter Lisa Stiffler can be reached at 206-448-8042 or lisastiffler@seattlepi.com

Add P-I Local headlines to