Noxious weeds are plants that when established are highly destructive, competitive, or difficult to control by cultural or chemical practices.  The State Noxious Weed Control Board (Board) must annually adopt a State Noxious Weed List and guidelines for placing plants on the list. 

There are three classes of noxious weeds:

1. Class A noxious weeds are noxious weeds not native to Washington and of limited distribution, or are unrecorded in Washington, but could cause a serious threat if established. 
2. Class B noxious weeds are non-native plants of limited distribution in a region of the state that could cause a serious threat in that region. 
3. Class C weeds are all other noxious weeds.

The guidelines for placing plants on the State Noxious Weed List must include criteria for reconsidering proposed new species not adopted by the Board, including any need for additional scientific data regarding invasive and noxious qualities of the proposed new species and from existing positive economic benefits, before taking action.  Once a State Noxious Weed List is adopted, County Weed Boards must select weeds identified on the state list for inclusion on the local noxious weed list for that county.

The guidelines for listing plants on the State Noxious Weed List that the State Noxious Weed Control Board (Board) adopts annually must prohibit the listing of agricultural crops as noxious weeds before the board receives and conducts a public hearing on recommendations provided by a workgroup convened by the Department of Agriculture.  At a minimum, the workgroup must include affected agricultural producers and one member of the Board.