Roadside spraying

We spray herbicide in some roadsides to control plant growth that might affect travelers’ sight distance, block travel or prevent drainage. 

Protecting the environment is a priority. We only spray priority locations to lessen environmental impacts. Roads within 30 feet of rivers are not sprayed. We do not spray within 250 feet of streams with salmon or steelhead trout. See our Road Maintenance Program for a list of roads scheduled for spraying.

Contractors usually spray roadsides each spring. Spray occurs at night using computer-assisted delivery systems to lessen exposure to the public. The process follows state and federal herbicide rules and laws. Contractors follow our Integrated Vegetation Management Program (IVMP) and Best Management Practices for Routine Road Maintenance. We use an approved mixture of products that includes:

  • Broad spectrum spray: Makaze (Glyphosate)
  • Broad spectrum companion spray: Escort XP (Metsulfuron methyl)
  • Broadleaf spray: TerraVue (Aminopyralid, Florpyrauxifen-benzyl)
  • Pre-emergent: EsplAnade 200 SC (Indaziflam)
  • Drift control and deposition aid: Liberate (Lecithin)

No Spray Agreements

You can opt-out of roadside spraying. Fill out the No Spray Agreement form and submit it through the Public Permitting and Services Portal. For “No Spray” signs, call 503-846-7623 or email.