Tree removal and trimming rules for unincorporated Santa Clara County, CA. Check your address to confirm you are outside city limits and see whether your tree needs a county permit.
County Zoning Division C16 protects (1) trees 12"+ in diameter (24"+ combined for multi-trunk) on Hillside-zoned parcels of 3 acres or less, in a "-d" Design Review district, or in the Los Gatos Hillside Specific Plan area; (2) any oak 37.5"+ in diameter anywhere in the unincorporated county; (3) heritage trees; and (4) trees required by past approvals. Dead, dying or hazardous trees are exempt, except heritage trees and protected oaks.
How to apply: Apply to the County Planning Office for an administrative tree removal permit at least 10 days before removal (no fee for the administrative permit).
How to measure: most Bay Area cities measure trunk diameter (or circumference) at 4.5 ft (54") above natural grade, but some measure elsewhere: Berkeley at 4 ft, Redwood City at the widest point between 6" and 36". Where a city sets its limit by circumference, we show the diameter (circumference ÷ 3.14).
Official sources: stgenpln.blob.core.windows.net/document/Ordinance_TreePresAn · plandev.santaclaracounty.gov/how/develop-or-improve-property