San Mateo County, CA Tree Protection: Tree Removal Permits (2026)

Ordinance No. 4895 (adopted October 22, 2024) consolidated the County's previous Heritage Tree and Significant Tree ordinances into a single Protected Tree Ordinance. Significant Tree threshold: 12.1 inches DBH (measured 4.5 ft above grade) countywide; 6+ inches DBH in the Residential Hillside (RH) District. Certain indigenous species — coast live oak (Quercus agrifolia), valley oak, California bay laurel, coast redwood, Douglas-fir, Monterey pine (native-range), madrone, and buckeye — have heightened protection at any size above a low threshold due to cultural and ecological value. A Tree Removal Permit from the Planning & Building Department is required unless the tree is exempt (dead, imminently hazardous, within 10 ft of a permitted foundation, or certain agricultural operations). Applications typically require a certified arborist report documenting health, hazard, or construction conflict, and a replacement plan. Unauthorized removal triggers significant fines per tree, a replacement requirement (often 2:1 to 3:1), and a hold on further permits. Erosion Control / Tree Protection Pre-Site Inspection is now required for all construction or demolition on specific site types.