Elodea Eradication Plan Would Employ Herbicide

Elodea. (Photo from the U.S. Fish & Wildlife Service)
Elodea. (Photo from the U.S. Fish & Wildlife Service)

A herbicide is proposed to eradicate an invasive weed that’s infested some Fairbanks area waters. The chemical application would target Elodea, a prolific aquatic weed known to choke out native plants and fish, and inhibit navigation.

Elodea was first documented in Alaska in 2010, in the Chena Slough in North Pole. It was subsequently tracked as far back as 1982 in Cordova’s Eyak Lake, and identified at numerous other Alaska sites in the Cordova, Fairbanks, Kenai and Anchorage areas. Fairbanks-based U.S. Forest Service Invasive Plants program manager Trish Wurtz says an herbicide called fluoridone has proven effective killing off Elodea in the lower 48 and on the Kenai.

“You can put a very low, small concentration of fluoridone in the water and it will kill the elodea, but either not harm or only slightly damage other aquatic plants,” Wurtz said. “And they rebound relatively quickly.”

Wurtz says a local group of agencies and is proposing to apply fluoridone to Chena Slough, and Chena Lake, a plan they’re taking public feedback on. The slough and lake and a portion of the Chena River are among 20 known Alaska Elodea infestations sites, including most recently Anchorage’s Lake Hood, the state’s biggest float plane base, and a means of carrying the invasive to waters all over Alaska.

Herbicide application may be the quickest way to halt Elodea. Wurtz says the decision to look at in the Fairbanks area follows an unsuccessful effort to use a suction dredge to vacuum up the plant.

“That didn’t work very well; it was extremely time consuming and labor intensive,” Wurtz said. “And after a couple hundred hours of suction dredging, they were only able to remove the elodea from about half an acre of Chena Slough.”

Wurtz acknowledges transitioning from a mechanical to a chemical approach raises the issue of side effects.

“The whole toxicology of chemicals in water, it’s a very complex issue, but this chemical has been used for years, and its approved by the EPA actually for use at 10 times the level that they’re using it on the Kenai,” Wurtz said. “And even if you used it at up to 10 times the amount, there’s no restrictions for people on drinking the water or swimming in the water. Even on the same day it’s applied.”

Elodea is believed to have made its way to Alaska by several avenues, including air craft floats boats, and other water sports gear and aquariums containing the plant that are inadvertently dumped into local waters.