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Pilots push for weed killer to combat Lake Hood's plane-fouling plants

  • Author: Zaz Hollander
  • Updated: September 28, 2016
  • Published July 10, 2015

A weed infestation so bad it's disturbing navigation for planes on Lake Hood has prompted the state to request an emergency herbicide application before someone gets hurt.

Lake Hood, known as the world's busiest floatplane base, is exploding with greenery fueled by this year's warm summer. But the lush underwater vegetation now includes recently discovered elodea, a leafy green aquarium plant invading Alaska's slow-moving waterways and crowding out native species.

Along with fouling planes, dense mats of elodea also snag boats, reduce property values, and can threaten salmon by sheltering predatory pike. Floatplanes in summer make hundreds of daily trips on and off Lake Hood, leading to concern elodea will spread to remote water bodies with the planes unless it's stopped.

Weeds like elodea pose a risk to aircraft because plant tendrils snare rudders and make planes hard to steer, especially on blustery days.

"You taxi in, the wind's blowing a little bit, you lose control and you could be in the path of a taking-off or landing plane," said Scott Christy, president of the Lake Hood Pilots Association. "It's real serious."

The safety risks are significant enough that the Alaska Department of Natural Resources on Thursday applied to the state Department of Environmental Conservation for an emergency exemption that slashes the time it would take to get a permit to apply herbicides to kill the weeds.

The DEC commissioner must approve the exemption. The agencies that manage Lake Hood -- Ted Stevens Anchorage International Airport and the Alaska Department of Transportation and Public Facilities -- support using herbicides. The state transportation commissioner has expressed that position to the DEC commissioner, Airport Manager John Parrott said.

Difficult summer

The airport's water-rescue boat responded to several floatplane pilots stranded in weed mats this summer, who were unable to control their direction with water rudders, Parrott said.

"It's been a difficult summer to operate," he said. "There's no question about it."

Ongoing state plans to apply herbicide to kill elodea in several other Anchorage lakes met with some criticism from members of the public concerned about everything from the potential risk of using chemicals to the contention that elodea has not been proven to be invasive.

Some of the streamlining in the emergency exemption process comes from the elimination of a public-comment period and a 45-day window that allows for permit review requests, both usually part of permitting.

DEC's pesticide program will weigh DNR's rationale for demonstrating an emergency exists in Lake Hood, said Karin Hendrickson, the state's pesticide program coordinator. Hendrickson will then make a recommendation to the commissioner on the exemption.

Rust's Flying Service, one of a number of commercial carriers operating air-taxi and flightseeing trips from the lake, cheered the emergency herbicide request.

"It gets to the point where you just can't steer," owner Todd Rust said of the submerged vegetation the called the worst he's seen in the lake.

The combination of windy conditions and rudder-fouling plants have forced a handful of company planes to stop and clear the gunk before taxiing in with clients, Rust said.

"We ended up on a shoreline," he said. "Basically, we had to beach on the shoreline to then remove the weeds so we could continue."

Success on the Kenai

First discovered near Cordova in the early 1980s, elodea has since been discovered in nearly 20 waterways in Alaska. Treatments with the herbicide fluridone substantially knocked down the weed in several Kenai Peninsula lakes last year.

The state's plans for Lake Hood call for a dose of a "contact" herbicide called diquat, followed by a follow-up application of fluridone, according to Heather Stewart, the state's invasive species program coordinator. The herbicides target elodea's roots to kill that plant permanently, but may cause a short-term die-off of a large amount of the lake's teeming native plants such as pondweed and milfoil, Stewart said.

Meanwhile, DNR is moving ahead with plans to apply herbicide to elodea in Sand Lake, DeLong Lake and Little Campbell Lake. Permit applications received a "finding of no significant impact," but a critic of the plans filed a request for a review, Stewart said. Depending on the outcome, fluridone application could begin as soon as Aug. 2.

At Lake Hood, any weed-killing activities will be done in conjunction with a 2005 aquatic vegetation management plan that lists hand-pulling, mechanical removal by a "lake rake" and seven different kinds of herbicides as potential control methods, Stewart said. The plan addresses the coming threat from vegetation for floatplanes.

Some pilots say the airport should have been more prepared for the elodea invasion and acted more quickly to stop it.

Christy, of the pilots association, said the group advocated for elodea readiness and invited experts to speak at meetings in 2011 to increase managers' attention as well as that of pilots. The airport made a plan, he said, but wasn't able to follow through quickly enough when elodea materialized, perhaps with a permit that's good for 5 years.

"We have a real problem and it didn't have to happen," he said. "If management had been on the stick and followed through, we wouldn't be in this situation now."

Parrott, however, said if the emergency herbicide use is approved, it will be faster than a conventional permit process. Elodea was first discovered in Anchorage in 2011 and those lakes are just now getting prepared for treatment. It was officially logged in Lake Hood last month.

"The fact that within a month we're close to ready and within two could be treating the lake that's not your typical bureaucratic glacial pace," he said. "There was nothing to do before it was discovered. You don't get a permit to treat something that hasn't shown up."

Making it worse?

Critics also say the way managers remove weeds now -- by chopping and hauling them out on a mechanical harvester dubbed the S.S. Minnow -- is actually making the outbreak worse.

The airport uses the device to maintain weed-free taxi lanes but elodea spreads easily and even broken bits and pieces can spark new growth. Stewart said elodea is only found sporadically in the lake now, in about 20 percent of shoreline survey areas, but fragments can drift to other parts of the lake and get established.

Parrott said the airport tried to avoid using the Minnow in elodea patches but resumed after the plans to treat the lake with herbicide materialized.

Meanwhile, there are reports that elodea is colonizing yet another floatplane destination, Campbell Lake.

Stewart said the state hasn't been able to survey that lake to confirm the presence of elodea and there are no plans currently to include Campbell in the Lake Hood permit exemption.

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