Noxious Weed Lists and Laws

King County Noxious Weed List

The King County Noxious Weed Control Board administers the state noxious weed law in King County.  Each year, the Board adopts the King County Noxious Weed List, which specifies which noxious weeds property owners are required to control in the county.  The county weed list includes all Class A weeds on the state noxious weed list, all Class B weeds designated by the state for control in the county, and any additional Class B or C weeds that are designated by the county weed board for required control in the county.  All Class A, B and C weeds on the county weed list need to be controlled by the property owner.

In addition to the regulated weeds, the county weed list includes state-listed Class B and C noxious weeds not designated for King County (Non-Designate Noxious Weeds) and additional invasive weeds that are not classified as noxious weeds on the state list but are problematic in King County (Weeds of Concern List).  Control of these weeds is not required in King County but it is encouraged and the county provides advice and technical bulletins to assist property owners with control.  Weeds of concern often impact and degrade native plant and animal habitat. The County Weed Board recognizes these plants are invasive and is collecting information and providing education on control. The Board encourages and recommends control and containment of existing populations and discourages new plantings.

Understanding the Washington State Noxious Weed Law

Noxious weeds are non-native plants that, once established, are highly destructive, competitive and difficult to control. They have economic and ecological impacts and are very difficult to manage once they get established. Some are toxic or a public health threat to humans and animals, others destroy native and beneficial plant communities.

To help protect the state's resources and environment, the Washington State Noxious Weed Board adopts a state weed list each year (Chapter 16-750 WAC), in accordance with the state noxious weed law (Chapter 17.10 RCW).  Noxious weeds are separated into classes A, B, and C based on distribution, abundance, and level of threat (how dangerous the plants is to humans, animals, private and public lands, and native habitats).

The goal of the state weed law is to prevent the spread of new and recently introduced weeds while it is still feasible to do so.  Class A weeds are the most limited in distribution and therefore the highest priority for control.  Class B and C weeds vary in priority based on local distribution and impacts.  Not all weeds are classified as noxious weeds in Washington State and only species that are not native to the state are considered for noxious weed listing.  Between November and April, any person may request a change to the Washington State Noxious Weed List for the following year.  For more information on the state's weed listing process and how you can participate, please contact the Washington State Noxious Weed Board. 

Noxious weeds are designated for control in all or parts of the state based on where it is still feasible to eradicate or contain the weeds.  Property owners, public and private, are required to control all Class A weeds and any Class B or C weeds that are designated by the state or county weed board for control in their area. "Control" is defined in WAC 16-750 as the prevention of all seed production.  Class A weeds need to be eradicated or removed entirely and Class B and C weeds designated for an area need to be controlled to prevent their spread.

The state noxious weed law also restricts the sale and transport of certain noxious weeds under its quarantine section.  For more information on these quarantines, contact the WSDA Nursery Inspection Program and read the Prohibited Plants List brochure.