San Mateo County, CA Tree Protection: Tree Replacement Requirements (2026)

Ordinance No. 4895 established a new in-lieu fee program and a Tree Replacement Fund administered by the Planning & Building Department. Replacement ratios scale with the size and species of the removed tree: 1:1 for smaller Significant Trees, 2:1 for larger specimens and native species, 3:1 or higher for Heritage Trees and rare natives (e.g., valley oak, California buckeye). Replacement trees must meet minimum size: 15-gallon containers for most species, 24-inch box for replacement of mature natives, and 5-gallon for slow-growing understory species. Approved species must be California native or drought-adapted non-invasive (no Arundo, pampas grass, eucalyptus, blue gum, Acacia dealbata). Replacements must be planted on the same property when feasible; where site conditions make that impossible (small lot, shading conflict, hazardous soil), the applicant pays an in-lieu fee set by the Planning Department per replacement tree, used by the County to plant trees on public lands or fund restoration projects. A 2-year maintenance period with a dead-tree replacement guarantee is standard.