Napa County, CA Landscaping Rules: Tree Removal & Heritage Trees (2026)

Napa County Code Chapter 18.108 (Conservation Regulations) is the primary tree-removal authority for unincorporated Napa County. Section 18.108.025 restricts vegetation clearing — including tree removal — within stream setbacks that vary by slope. Section 18.108.027 (Sensitive Domestic Water Supply Drainages) requires that at least 70% of the tree canopy cover existing on June 16, 1993, plus understory vegetation, be maintained on any parcel subject to earth-disturbing activity; where vegetation is shrub and brush only, the retention floor is 40%. The 2019 Water Quality and Tree Protection Ordinance (adopted 5-0 by the Board of Supervisors after Measure C narrowly failed in June 2018) increased oak woodland mitigation ratios, established setbacks from wetlands, municipal reservoirs, and ephemeral streams, and exempted Cal Fire-guided fire management. Tree removal for new vineyards on slopes over 5% requires an Erosion Control Plan (ECPA). Riparian tree removal may also require permits from the California Department of Fish and Wildlife (§1602) and the US Army Corps of Engineers. Measure C, the Watershed and Oak Woodland Protection Initiative, would have capped vineyard-driven oak removal at 795 acres before triggering a permit system; it was defeated 51% to 49% in 2018.