Olympia, WA Invasive Plant Rules: Prohibited Species (2026)

Olympia does not print a plant-by-plant ban list in its noxious weed chapter. Section 16.18.010 says noxious weeds are governed in detail by the Noxious Weed Control Board, so the City of Olympia regulates only the duty described in Chapter 16.18. Section 16.18.020 names thistles and tansy ragwort and then reaches any other such noxious weed growing on land in the City, whether improved or unimproved, enclosed or not enclosed.

The duty falls on every owner, lessee, occupant, or agent, and on any person having the care and charge of the land. It covers any road, street or highway bordering the land, to the center of it. If the City owns the road in fee simple, the adjacent owner is not subject to that duty. Control methods must be acceptable to and recommended by the Thurston County Weed Control Board.

The City Engineer or designee enforces the section through the Public Works Department. Written notice gives the owner ten (10) days from service to control the weeds. When the owner refuses or neglects, Public Works enters the land and has the weeds controlled with as little damage as possible to any growing crops. A nonresident owner with no known agent in the City gets notice posted in a conspicuous place on the land, and a railroad can be served through its section foreperson or any agent of the company within the City.

The Property Maintenance Code adopted in OMC 16.06.010 and amended in 16.06.020 adds its own rule in section 302.4: premises and exterior property must be kept free from weeds or plant growth in excess of 12 inches, and noxious weeds are prohibited. Agricultural areas within the City of Olympia (crops, livestock, farming, etc.) are exempt from that subsection.