Headwaters to Harbor: Lewis County Battles Against Noxious Weeds on Chehalis River

Lewis County Noxious Weed Control Staff Wage Seemingly Endless War on Brazilian Elodea, Knotweed


Editor’s Note: This story is part of "Headwaters to Harbor," a project by The Chronicle to document the Chehalis River from Pe Ell to Grays Harbor while highlighting people and issues connected to the river along the way. Our coverage is compiled at www.chronline.com/Chehalis-River.

Lewis County Noxious Weed Control staff think it started in Plummer Lake in the 1990s, when someone carelessly emptied a fish tank.

From there, non-native, invasive Brazilian elodea entered the Chehalis River system. Now, it’s found from Lewis County to Grays Harbor County.

Brazilian elodea might be a nice decoration for a fish tank. But outweighing its beauty are its menacing effects. Sucking up oxygen that aquatic species need, covering rocks on the riverbed with slimy, mossy stems, the plant is changing the landscape for the worse.

At Rainbow Falls State Park on Sunday morning, The Chronicle met with Lewis County Noxious Weed Control staff to discuss Brazilian elodea and other invasive plants that threaten the Chehalis River.

The park has a history of being the site of invasive knotweed, which Danika Davis, Noxious Weed’s weed specialist, called a “huge problem” and the “county’s No. 1” worst weed.

Davis added that choosing which is the county’s biggest weed enemy was a “loaded question,” because all noxious weeds pose different risks to the livelihood of residents for various reasons.

Knotweed is just particularly hard to eradicate.

State law dictates it is a landowner’s responsibility to take care of what are considered to be “noxious weeds.” Charles Edmonson, Lewis County Noxious Weed program coordinator, said the definition is a legal term — not necessarily meaning the weed is poisonous. Some weeds are poisonous to humans, while others are classified as noxious due to threats posed to ecosystems, infrastructure, livestock and even property values.

Edmonson and Davis, therefore, don’t just assume landowners know what is and isn’t a noxious weed. Part of their job is educating the public with home visits and letters, events and informational packets.

“Education is power,” Davis said. “The more you know, the more we can all work together and help each other.”

Unfortunately, fighting the noxious weeds of the Chehalis Basin sometimes feels like a losing battle. Denise Wagner, a former weed technician with the county, spent 12 years fighting back knotweed from Pe Ell to Lintott-Alexander Park alone.

“I am very proud of my hard work/accomplishments towards eradicating invasive knotweed on the upper thirty river miles of the Chehalis River,” Wagner said in an email to The Chronicle, but added that, “Those last few clumps I could not kill will always haunt me. If only I were a bit younger I could have kept at it and saved the river.”

Knotweed is troublesome for a variety of reasons, including its destructive abilities. A bamboo-like stem with shield-shaped leaves, the plant can grow through cement, plumbing, porches and other man-made structures. Its shade impacts native plant growth on the riverbanks. Knotweed also dies back every winter, so it doesn’t offer bank stabilization during the flood season. The weed can shoot up as much as 12 feet during a growing season.

It can be seen in abundance downstream of Lintott-Alexander Park in Chehalis.

For landowners, it can be tough to tackle. If even one 2-inch stem remains, it can take root. Herbicide can’t be sprayed near water without a special permit from the Department of Ecology.

“If we could tell anybody one thing about it, it would be ‘don’t mow it,’” Davis said. “You’ll have to mow it every two weeks, literally, for three to seven years.”

One goal Davis and Edmonson talked about for the future is helping more residents get the proper licensing for aquatic herbicide use.

The fight against Brazilian elodea is similarly frustrating, they said. Right now, Noxious Weed staff are trying to approve treatment of Plummer Lake. Without chemical treatment, the plant has to be physically removed from the riverbed by divers. If even a small piece remains, it will float downriver and take root.

The staff remain hopeful in their fight — even if it sometimes feels like a losing battle — because the weeds impact residents regardless of where or how they live their lives.

“(Noxious weeds) can influence and touch people’s lives in a lot of different ways that they don’t even realize,” Davis said.

But, that’s why the staff do what they do.

“We're pushing so much for more education and outreach. We want the community to see us as an approachable entity,” Davis said.

To learn more about noxious weeds and what to do about them, visit https://lewiscountywa.gov/departments/weed-control/.