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King County Washington home

Pest management

Since 1999, King County has required the use of Integrated Pest Management (IPM), a comprehensive approach to pest control. IPM focuses on preventing problems first and using chemical controls only as a last resort. The program evaluates different strategies and promotes non-chemical methods when they are effective and practical.

Under IPM, pesticides are grouped into three tiers:

  • Tier 3: Lowest hazard
  • Tier 2: Moderate hazard
  • Tier 1: Highest hazard

If the pest is a state regulated noxious weed can only be controlled with a Tier 1 pesticide, staff must submit a Tier 1 Product Exception Request (Short Form Template | Long Form Template) to the IPM administrator

Policy and Goals:

From IPM Executive Policy and Tri-County IPM Policy:

  • Reduce the impact of pesticide use on protected species, including Puget Sound Chinook salmon and bull trout. 
  • Improve public health and protect the environment in King County. 
  • Manage the long-term effects of vegetation and pest problems. 

Example - Natural Vegetation Management with Goats

King County Metro Transit has used goats to manage blackberry bushes and other weeds at several park-and-ride lots. These areas are hard to maintain because of steep slopes and uneven ground. Goats provide an efficient, safe, and chemical-free way to control weeds. The service is needed twice a year to stop new plant growth. Results were so positive that King County expanded the program and continues to use goats where needed.

Best Practices

  • Choose and properly maintain the appropriate plants for the area.
  • Document and identify potential pests and determine a tolerance threshold.
  • Put up physical barriers or remove the pest by hand.
  • Obtain a permit from WSDA, USDA, EPA, etc. or a biological management activity, which includes using animals, insects of competing vegetation to control the pest.
  • Use chemical pesticides as the last resort and don't over fertilize. 

Quick Tips

Choose

  • Integrated Pest Management (IPM) strategies
  • Biological controls (beneficial insects, microorganisms)
  • Tier 3 pesticides (lower toxicity, targeted)
  • Natural vegetation management (e.g., native plantings, mowing practices)
  • Require IPM in service contracts
  • Natural, organic, or slow-release fertilizers that minimize runoff
  • Spot-spray treatments rather than blanket applications

Avoid

  • Broad, indiscriminate chemical use
  • Tier 1 pesticides (most hazardous)
  • “Weed & Feed” fertilizer/herbicide mixtures

End of Life

  • Find an appropriate user for surplus materials through the Industrial Materials Exchange
  • Recycle or dispose of products through King County’s Local Hazardous Waste Management Program

An EPA checkmark indicates a certification or standard is recommended by the U.S. Environmental Protection Agency (EPA).

Click here to access a spreadsheet of Tier Classifications.

Ranking by Tiers as Classified by King County and the City of Seattle Tier Definitions

Tier 1: Highest concern, highest priority for phase out

Includes products that: 

  • Carry the hazard signal word DANGER 
  • Are restricted-use pesticides (except aquatic herbicides) 
  • Cannot be disposed of due to dioxin contamination 
  • Contain active ingredients on the state’s acutely dangerous waste list 
  • Are known, likely, or probable carcinogens 
  • Contain reproductive toxicants (CA Prop 65 list) 
  • Are known or probable endocrine disruptors 
  • Are highly or extremely toxic to birds, aquatic species, bees, or wildlife 
  • Have active ingredients with soil half-lives longer than 100 days 
  • Have high mobility in soil or specific label warnings about groundwater hazard 

Tier 2: Moderate concern, second priority

All products not specifically assigned to tier 1 or tier 3. 

Tier 3: Lowest concern

Includes products that meet all of the following: 

  • No possible or probable carcinogens 
  • No reproductive toxicants (CA Prop 65 list) 
  • No endocrine disruptors (per Illinois EPA list) 
  • Active ingredients have a soil half-life of 30 days or less (minerals exempt) 
  • Very low or extremely low soil mobility 
  • Not labeled as toxic to fish, birds, bees, wildlife, or domestic animals

Tier 4: Insufficient information available

Products with missing registration or ingredient data. Cannot be assigned to another tier. 

High Performance Buildings Guide: Pest Management 

King County Noxious Weeds: Best Management Practices 

City of Seattle: Integrated Pest Management