2020 Noxious Weed List


The Stevens County Noxious Weed Control Board believes the prevention and eradication of newly invading noxious weed species yields the greatest return for the resource investment. This is best achieved through an intensive survey and inventory program allowing for early detection and early action. Education and awareness are an integral part of prevention, early detection, and early action. Being familiar with what is growing around us is the best way to assure that when a new invader arrives, it will be noticed and can be dealt with at the most effective stage.

The Stevens County Noxious Weed Control Board of Directors adopted all Class A, all Class B-designate, and certain Class B/C select noxious weeds from the 2019 WA State Noxious Weed List (WAC 16-750). Even though we include all A and B designate weeds on our county list, only those that are currently or are known to have grown previously (within the past 5 years) are listed here. They are divided according to control requirements.

Class A

These Class A weeds have been found as single plants or in very limited populations in the county. Eradication may be required. Prevention and early detection are the best defense against these weeds.

Class B

These Class B Designate weeds are located in certain areas of the county in limited or moderate populations. Inventory and education, preventing further spread, reducing population sizes and density, are the priorities.

Class B select or Class C

The following are Class B select or Class C select weeds, elevated by the county weed board to required control- as outlined in section (2) above- everywhere in the county.


Class B select

These Class B select weeds are normally grown as ornamentals. If they are found to have escaped intentional landscape plantings and appear to be spreading off site control will be required.

Class B Designate

NOTE: Special control requirements for the below listed weeds.

Where there are light to moderate infestations they have been designated by the State Weed Board as a Class B designate. Outside of the State designated areas, the county weed board has made these Class B select weeds with control requirements differing by weed as described below:

  • plumeless thistle, Carduus acanthoides
    Class B Designate in all areas lying south of State Hwy 20; Class B Select north of Hwy 20.
    Control is required EVERYWHERE in the county.
  • rush skeletonweed, Chondrilla juncea
    Class B Designate in all areas north of Township 28N. South of this (SCT 27&28) a control buffer strip of at least 40′ wide must be maintained on all property boundaries including road corridors.
  • yellow starthistle, Centaurea solstitialis
    Class B Designate in all areas except T36 R38 in the area contained within Hwy 395/Hwy 20, Pingston Creek Road, and Highland Loop Road. Within this area, a control strip of at least 40′ wide must be maintained on all property boundaries and road corridors.

Class B Select

The below Class B Select weeds exist in moderate to heavy populations in much of the county. To help prevent further spread of these weeds, a control strip of at least 40′ wide must be maintained along property boundaries, including travel corridors. Beyond this strip, the focus will be on assisting land owners with control recommendations and technical assistance, and utilizing biological control upon request- when it is available.

NOTE: The populations of these two knapweed species are diminishing due in part to the biological control agent which is widespread across Stevens County at this time.


At the discretion of the Weed Board, any site infested with state listed noxious weeds, whether within an area where the weeds are normally required to be controlled or not, that poses a threat of spread of propagules (seeds, roots, vegetative parts) through the transport of contaminated materials, may be subject to control requirements. These sites include but are not limited to gravel pits, sand quarries, landscape materials, etc.