Invasive Species and Noxious Weeds

Invasive species are those that have been introduced to an area from other parts of the world; they have an adverse affect on the habitats they invade economically and/or ecologically. “Invasive” is not a legally defined classification. In comparison, noxious weed is a legally defined term in Washington State. All noxious weeds are invasive species, but not all invasive plant species are categorized as noxious weeds. Noxious weeds are non-native, aggressive and invasive, but have the potential to be eradicated or controlled within Washington.  For example, the Himalayan blackberry pictured on the left is an invasive plant. However, it is so widespread that it can never be eradicated or controlled within Washington – therefore, it is not classified as “noxious weeds”.

The Washington State Noxious Weed Control Board determines which plants are placed on the Washington State Noxious Weed List (WAC 16-750). The Board adopts a State Noxious Weed List each year, categorizing weeds into three major classes: A, B, and C, according to the threat they pose to the state or a region of the state.  Definitions of these classes can be found on the Washington State Noxious Weed Control Board website.

A knotweed plant, sprouting up through pavement.

The Whatcom County Noxious Weed Control Board then holds a public hearing to adopt the county list. The Whatcom County noxious weed list is made up of all Class A weeds, Class B-designates, and any selections by the County Board from the Class B or Class C weed list. Any Class A or Class B-designates on the Washington State List are mandatory for adoption and control at the county level.

The City of Bellingham works toward controlling invasive species using a variety of methods in an integrated pest management program. Salmon-friendly invasive species control methods include:

  • Mechanical (“by hand”) tillage, using plows, disks, or cultivators. Not to be done when plants are flowering or with Japanese Knotweed.
  • Mowing, hoeing, hand digging and pulling.
  • Mulch, plastic sheeting, and other physical barriers.
  • Natural predators, use of shade, water logging, and vegetative competition.

For More Information

There are many excellent resources on the Internet with detailed information about noxious weeds. The Whatcom County Noxious Weed Control Board website also has extensive fact sheets on the noxious weeds identified in Whatcom County.