San Mateo County, CA Tree Protection: Heritage & Protected Trees (2026)

The Protected Tree Ordinance consolidated previous Heritage and Significant Tree protections and established new findings and review criteria for Heritage Tree designation. Criteria considered include: trunk diameter (typically 24+ inches), species rarity or native-range status, historical or cultural significance (trees on historic properties or with documented community importance), and exceptional ecological or aesthetic value (specimens, habitat trees). Residents can nominate trees for Heritage status via the Planning Department; final designation is by the Planning Commission or Board of Supervisors. Heritage Trees receive maximum protection: removal requires Planning Commission approval with findings that no alternative exists and removal is necessary for public safety or an unavoidable conflict. Construction projects near Heritage Trees must implement Tree Protection Zones (typically 1 ft radius per inch of DBH), root protection barriers, and have a Certified Arborist on site during ground-disturbing work within the TPZ. Damage to Heritage Trees during construction — including root cutting, grade changes, or trunk damage — triggers both administrative penalties and restitution calculated via the Trunk Formula Method (ISA appraisal).