Contra Costa County, CA Landscaping Rules: Weed Ordinances (2026)

California Food and Agricultural Code Section 5004 directs the California Department of Food and Agriculture and county agricultural commissioners to identify and control pest plants. The Contra Costa County Department of Agriculture maintains a local noxious weed program targeting A-rated weeds (artichoke thistle, yellow starthistle in some contexts, hydrilla) that require mandatory eradication and B-rated weeds that require local control. Invasive species of particular concern in the county include artichoke thistle (Cynara cardunculus), medusahead, barbed goatgrass, and arundo along waterways. Property owners identified as harboring noxious weeds receive a written notice and 30-day cure period; if the weeds are not removed the county may enter the property (with consent or by warrant) and perform abatement, billing the owner. Chapter 416 of the county code provides the local abatement authority, and Chapter 438 restricts the sale or transport of regulated invasive plants. Cooperation with East Bay Regional Park District and open space districts is common for watershed protection. Homeowners should also avoid planting Italian thistle, pampas grass, and English ivy, which are listed as invasive by Cal-IPC though not A/B regulated.