Invasive Plants

Invasive plant species can have a negative impact on the health and function of our natural environment, including our streams, wetlands, and lakes. Invasive plants displace beneficial native vegetation, impair water quality, and contribute to streambank erosion. The removal and control of these plant species is very important to improving the health of our aquatic areas.

Japanese Knotweed

A large patch of Japanese Knotweed on the bank of a river channel

English Ivy

A patch of English Ivy

Yellow Flag Iris

A patch of Yellow Flag Iris

Yellow Archangel

A patch of Yellow Archangel

Reed Canary Grass

A field of Reed Canary Grass

English Laurel

An English Laurel plant

The resources below can help you identify the invasive plant species on your property and determine the best options for controlling them.

  • Snohomish County Noxious Weeds
    The Snohomish County Noxious Weed Control Board is a great resource to find information on weed infestations in Snohomish County. Additionally, they are a great resource for identifying weeds and for information on control options. This webpage also includes an option to report noxious weeds sightings.
  • King County Noxious Weeds
    King County Noxious Weeds has several resources for common invasive species that are relevant to residents in Snohomish County. This website contains several useful factsheets detailing best management practices for controlling common weeds in Snohomish County, including blackberry, knotweed, yellow flag iris, and many others.
  • WA State Noxious Weed Board
    The Washington State Noxious Weed Board determines invasive plant listings statewide. Their website also includes helpful information on state weed laws, and on weed identification and control.
  • Weed Control Videos
    Videos produced by the West Multnomah Soil & Water Conservation District provide useful, how-to information on control methods for several common invasive plants found in Snohomish County.