FAIRBANKS—An aquatic weed previously thought to have invaded only Interior waterways around Fairbanks has now been spotted downstream of Nenana.

Staff from two federal agencies confirmed last week that thick patches of elodea are growing in Totchaket Slough, a small side stream of the Tanana River about 12 miles from Nenana, according to the Fairbanks Soil and Water Conservation District.

The district plans to do a more thorough survey this week, but the local quasi-governmental organization wants to get out the word that it's important to clean boats and ATVs to prevent the invasive plant from spreading farther, District Coordinator Joni Scharfenberg said.

"Just a fragment from somewhere can spread and start somewhere else," she said. "We do not know how it got into Totchaket Slough. There's a lot of speculation but we don't know for sure."

A public affairs campaign by several agencies working to stop elodea's spread urges boaters to "rinse, drain and dry" boats and other gear before putting them into new bodies of water.

Workers from the Tanana Chiefs Conference detected the most recent elodea outbreak and brought it to the attention of the National Park Service and the U.S. Fish and Wildlife Service last week, Scharfenberg said.

Elodea is an aquatic weed first found in the Interior in 2010, probably from people dumping out aquariums. The plant concerns biologists because it crowds out native plants and can make waters hard to navigate by tangling in boat propellers.

Once it spreads, the weed is labor-intensive to remove. A state-led elodea committee plans to poison the elodea previously found in Chena Slough with an herbicide called fluridone starting as early as 2016, although the group lacks the hundreds of thousands of dollars needed to fund the herbicide treatment.

Elodea has previously been spotted in Chena Slough, Chena Lake and in a small part of the Chena River near where the Tanana Chief riverboat docks in west Fairbanks, according to Aditi Shenoy, the Soil and Water Conservation District's invasive weeds specialist.

The new elodea outbreak covers more than 95 percent of the surface of the water in a half-mile section of Totchaket Slough, according to Shenoy. The plant covers a more-than 3-mile section of the slough in lesser concentrations.

The Soil and Water Concentration District urges people who find elodea to call 1-877-INVASIV, the Alaska Department of Fish and Game's invasive species hotline.

Contact Outdoors Editor Sam Friedman at 459-7545. Follow him on Twitter: @FDNMoutdoors.

Correction: This article has been changed to reflect the following correction.

The elodea was found to the north of the town of Nenana. The Tanana River flows south-to-north in this section. The elodea is downstream of Nenana. An earlier version of this story also misspelled Totchaket Slough.