This summer the invasive waterweed elodea was eliminated from two of the three infected lakes on the Kenai Peninsula. However, recently discovered elodea in Anchorage’s Lake Hood, which Ted Stevens International Airport manages as the world’s largest floatplane base, creates the risk that elodea will not only be reintroduced to the Kenai Peninsula, but will spread further through Alaska.

Elodea, originally introduced as an aquarium plant, can overwhelm a lake’s ecosystem by growing in great masses that restrict water and wildlife movement, increase sedimentation, and reduce the water’s oxygen content.

For floatplane pilots, elodea-clogged waters are navigational hazards ­— the weed can snare a plane’s water rudders, leading to a loss of control. Elodea can reproduce asexually by fragmentation, allowing it to spread from lake to lake via fragments caught in floatplane rudders or floats. Because floatplanes can reach Alaska’s hundreds of remote lakes inaccessible by road, they have the potential to spread the elodea population to areas difficult to observe or control.

Scott Christy, President of the Lake Hood Pilots Association, said that since the discovery of the Lake Hood elodea he has advocated for quick action to eliminate it. However, Christy wrote in an email that for Ted Stevens International Airport or the Lake Hood Pilots Association to apply herbicides without a permit from the Alaska Department of Environmental Conservation would be “highly illegal.”

“It is up to airport management to apply for an emergency permit to add any chemicals to the lake,” Christy wrote. “I hope they will sooner (rather) than later.”

The Alaska Department of Natural Resources is leading an elodea eradication effort involving several state and federal agencies and environmental non-profits, which on the Peninsula includes the Kenai National Wildlife Refuge.

This summer, Refuge biologist John Morton announced that the elodea populations in Nikiski’s Beck and Daniels Lake had been killed with the herbicides diquat and fluridone, while the similarly-treated Stormy Lake was nearly elodea-free.

The Peninsula herbicide program had been permitted by the Alaska Department of Environmental Conservation, which required a 30 day comment period and a 45 day period for requested reviews.

DNR has applied for an emergency permit to attack the Lake Hood elodea in an method similar to that used in Nikiski’s Daniels Lake, using the contact-killing herbicide diquat and the more thorough fluridone.

The emergency permitting process will eliminate both the review and the comment periods. Herbicide application could begin in Lake Hood as soon as August 2.

After the success of the herbicide program in the three Peninsula Lakes, the Kenai Peninsula Borough appropriated remaining money from the $400,000 state grant it received for its own elodea eradication program to buy herbicide for the anticipated elodea treatment in Lake Hood.

In the meantime, pilots flying to and from Lake Hood, or any water body that might contain invasive species, can avoid spreading the weed by manually inspecting and cleaning their floats and rudders before take-off.

A less effective measure, Christy saud, is to circle the water body after take-off and cycle the plane’s water-rudders to dislodge any plant material that may still remain.

Reach Ben Boettger at ben.boettger@peninsulaclarion.com