Marin County, CA Invasive Plant Rules: Prohibited Species (2026)
Key Facts
- Governing section
- § 6.60.010, Noxious weeds listed
- Listed species count
- 13 named weeds
- Penalty
- Misdemeanor, fine up to $50 (§ 6.60.020)
- List expansion
- Agricultural commissioner may add species by order
- Adopted
- Ordinance No. 968 (1959)
Summary
Marin County Code Section 6.60.010 makes it unlawful to knowingly let 13 named noxious weeds, including Canada thistle, Russian knapweed, and puncture vine, grow on land you own. Violating the 1959 ordinance is a misdemeanor under Section 6.60.020, punishable by a fine capped at fifty dollars.
6.60.010 - Noxious weeds listed. It shall be unlawful for any person owning land within the county of Marin to knowingly permit the following noxious or deleterious weeds to exist, grow or mature upon land owned by such person: Russian thistle, puncture vine, hoary cress, Austrian field cress, Klamath weed, white horse-nettle, creeping sow thistle, milk thistle, bull thistle, Canada thistle, Italian thistle, Russian knapweed, Iberian thistle, and any weed pest that may by written order be declared detrimental to agriculture within the county of Marin by the Marin County agricultural commissioner with the approval of the director of the California Department of Agriculture.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 2026 Update 1).
Full Breakdown
60 (Noxious Weeds) dates to Ordinance No. 968, adopted in 1959, and remains in the current County Code. 010 names the covered species outright: Russian thistle, puncture vine, hoary cress, Austrian field cress, Klamath weed, white horse-nettle, creeping sow thistle, milk thistle, bull thistle, Canada thistle, Italian thistle, Russian knapweed, and Iberian thistle. The list isn't fixed forever: the same section lets any weed pest be added if the Marin County agricultural commissioner declares it detrimental to agriculture with the approval of the Director of the California Department of Agriculture, so newly identified invasive weeds can be folded in by written order without a new ordinance.
The duty falls on the landowner: it's unlawful to knowingly permit any listed weed to exist, grow, or mature on land you own, meaning enforcement turns on knowledge of an infestation rather than strict liability for whatever blows onto a property. This sits alongside, and predates, the County's broader vegetation and fire-fuel rules; it doesn't require a permit or inspection scheme on its own, and it carries no acreage or agricultural-use carve-out in its text. 11, is the natural enforcement point given its statutory role identifying agricultural pests countywide.
Violations & Fines
Section 6.60.020 makes any violation of Chapter 6.60 a misdemeanor, punishable on conviction by a fine not to exceed fifty dollars, a low ceiling the ordinance has carried unchanged since 1959. The chapter doesn't provide a separate administrative-citation or daily-penalty track of its own, unlike the County's newer nuisance-abatement ordinance, so a weed complaint that isn't resolved informally would proceed as a misdemeanor prosecution under this section.
Frequently Asked Questions
Which weeds are banned under Marin County's noxious weed law?
What's the penalty for letting a listed weed grow?
Can the County add new invasive weeds to the list?
Do I have to actively remove weeds I didn't plant?
Sources & Official References
Other rules in Marin County
California rules heatmap·Compare Marin County to another location·View the California invasive plant rules overview
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