Knock-out Knotweed

Knotweed is a destructive plant species that destroys native ecosystems, takes over entire riverbanks and degrades fish habitat, reducing the recreational quality of Pacific Northwest rivers. Knotweed is a Class B noxious weed and Skamania County Noxious Weed Control Board requires property owners to control knotweed. Knotweed easily spreads from site to site during flooding events.  It is extremely important to dispose of knotweed properly. Never put knotweed in with yard waste, toss over banks or include in compost. Do not dump plants with yard waste or leave cut stems on the ground. Even the smallest fragment can sprout and grow with minimal moisture.

Initiated in 2002, the Noxious Weed Program began a project to locate and control the spread of knotweed species in Skamania County. The project is crucial to preserving the native plant species and riparian habitat throughout Skamania County. If you have suspected infestations of knotweed, please contact us as soon as possible. Staff will provide technical assistance with control and opportunities for treatment at no cost may be available. For more information please contact Cyndi Soliz at or by phone at 509-427-3942.


Contact us

Office Hours:            6:30 - 4:30 Monday to Thursday

Office Location:      704 Rock Creek Drive Stevenson, WA 98648

Mailing Address:        PO Box 369   Stevenson, WA 98648

Phone: (509) 427-3941 Email: Weeds

Learn more

Noxious weeds: FAQ

Get help and participate

Noxious weed list and laws

Weed Prevention

Methods of control


Toxic Plants








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