King County, WA Invasive Plant Rules: Prohibited Species (2026)
Key Facts
- Definition source
- Adopts WA state list, WAC 16-750
- Removal method
- Hand labor unless board authorizes otherwise
- Annual assessment
- $8.122/parcel plus $0.58/acre
- Enforcement
- Civil penalty or misdemeanor, up to $1,000
- Applies to
- Unincorporated King County only
Summary
Unincorporated King County treats any plant on Washington's official noxious weed list, WAC chapter 16-750, as a regulated noxious weed under county code, regardless of the list's regional designation, and funds enforcement through an annual per-parcel assessment.
Noxious weed: a plant species that is highly destructive, competitive or difficult to control by cultural or chemical practices, limited to any plant species listed on the state noxious weed list in chapter 16-750 WAC, regardless of the list's regional designation or classification of the species. (Ord. 15051 § 81, 2004: Ord. 10870 § 203, 1993).
21A.06.817 Off-street required parking lot. Off-street required parking lot; parking facilities constructed to meet the off-street parking requirements of K.C.C. 21A.18 for land uses located on a lot separate from the parking facilities. (Ord. 13022 § 4, 1998).
21A.06.820 Open-work fence. Open-work fence: a fence in which the solid portions are evenly distributed and constitute no more than fifty (50) percent of the total surface area. (Ord. 10870 § 204, 1993).
Full Breakdown
King County Code Section 21A.06.815 defines a noxious weed as any species on Washington's state noxious weed list in WAC 16-750, regardless of regional classification, so every listed plant is regulated countywide. Within critical areas and their buffers, removing noxious weeds or invasive vegetation is allowed without a permit under K.C.C. 21A.24.045 only by hand labor, unless the King County Noxious Weed Control Board authorizes mowers or herbicides; the cleared site must then be stabilized against regrowth and revegetated with native or climate-adaptive plants. The county also charges an annual noxious weed control assessment of $8.122 per parcel plus 58 cents per acre under K.C.C. 4A.670.200 to fund the program.
Violations & Fines
Using herbicides or machinery without Noxious Weed Control Board authorization voids the critical-area exemption; violations become Title 23 code-compliance cases, with civil penalties or a misdemeanor fine up to $1,000 and 90 days in jail.
Frequently Asked Questions
Does King County publish its own list of banned invasive plants?
Can I spray herbicide on noxious weeds in a critical area buffer?
Does this rule apply inside Seattle or Bellevue?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington invasive plant rules overview
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