Cook County Tree Preservation Ordinance 19-3158, codified in Chapter 102 zoning, requires removal permits for protected and heritage trees on unincorporated lots. Native oaks, hickories, and trees over 20-inch DBH are protected; replacement and mitigation are mandatory for permitted removals.
Cook County Tree Preservation Ordinance 19-3158 (adopted 2019, codified in Chapter 102 zoning) governs tree removal on unincorporated Cook County properties of one acre or larger and on all developments requiring zoning approval. The ordinance protects native oak species (Quercus alba, Q. rubra, Q. macrocarpa, Q. velutina, Q. ellipsoidalis), hickories (Carya), and any tree of 20-inch DBH or greater regardless of species. Removal requires a tree removal permit from Building and Zoning, replacement at a mitigation ratio scaled by DBH (often 1 inch removed = 1.5 inches replanted), and species selection from the county's native plant list. Suburban municipalities run separate tree ordinances; the county rule applies only in unincorporated areas.
Unpermitted removal of a protected oak, hickory, or 20-inch-DBH tree on unincorporated Cook County land violates Ordinance 19-3158 and triggers per-inch-DBH fines plus mandatory replacement. Developer-scale violations can carry $5,000+ daily fines and stop-work orders.
See how Oak Park's protected tree species rules stack up against other locations.
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