Riverside County, CA Tree Protection: Tree Ordinances (2026)

Tree regulation in unincorporated Riverside County comes from multiple overlapping ordinances and state statutes. Ordinance No. 559 is the primary oak preservation ordinance, protecting native oaks 6 inches DBH and larger. Ordinance No. 457 regulates tree-trimming and removal in the public right-of-way, requiring an encroachment permit from the Transportation Department. The Western Riverside County MSHCP covers approximately 1.26 million acres and restricts vegetation disturbance in conservation areas. California Public Resources Code §4291 requires 100 feet of defensible space around structures in State Responsibility Areas (SRA), which includes most unincorporated foothills and mountain areas — trees and vegetation must be cleared or thinned per Cal Fire guidelines. CA Government Code §51182 adds Very High Fire Hazard Severity Zone requirements. The Desert Native Plants Act regulates desert flora. Urban forestry on county-maintained roads is managed by the Transportation Department, and homeowners must obtain permits before topping or removing parkway trees. Violations of tree ordinances can carry fines of $100-$10,000 per tree plus mandatory mitigation.