Noxious Weed Class Definitions & Criteria

In an effort to prioritize the necessary work for noxious weed prevention and management, the Washington State Noxious Weed List is separated into three levels of classification. The categories are as follows:

  • Class A
    • A serious threat
    • Goal: eradication
    • Limited distribution, new invader
    • Not native to the state
    • Prevention of seed production mandated statewide
Flowering Rush - Class A
  • Class B
    • A serious threat to uninfested areas
    • Abundant in some areas; unrecorded or of limited distribution in other areas
    •  Not native to the stat
    • Prevention of seed production in designated areas / counties
    •  Goal: containment and eventual eradication  


  •  Class C
    • Abundant or widespread 
    • Any other noxious weeds 
    • Control at county discretion 
    • Weeds of special interest or concern 
Tansy Ragwort - Class B