Spokane County, WA Invasive Plant Rules: Prohibited Species (2026)

32 of the Spokane County Code establishes a weed extermination area covering the entire county for destroying noxious and poisonous weeds identified by the Washington State University Agricultural Experiment Station as detrimental to agriculture or livestock. 010 names the founding list: Russian Thistle, Farm Weed, Jim Hill Mustard, Canada Thistle, Quack Grass, Morning Glory, California Puncture Vine, Russian Knapweed, White Top, Blue Flowering Lettuce, Perennial Sow Thistle, Wild Snapdragon and Klamath Weed. 020 requires Canada Thistle, White Top and Russian Knapweed to be cut or otherwise prevented from going to seed before or during the blooming period, at the landowner's cost.

030 requires Leafy Spurge to be eradicated wherever found and confines the Klamath Weed mandate to a mapped area north of the Spokane River between Forker Road and the Idaho line, and south and west of the river outside four listed sections. 040 sets June 1 as the yearly deadline for action against Dalmatian Toadflax, approves borate and borate-chlorate herbicide mixtures for its control, and makes eradication of scattered infestations mandatory in the judgment of the Board of County Commissioners or its weed inspector. 050 adds Yellow-Flowering Skeleton Weed to the mandatory-eradication list.

In every case, if the landowner fails to act, the county weed inspector eradicates the weed and bills the owner; unpaid costs become a lien on the land, collected the same way as a delinquent property tax.