Lake County, IL Tree Protection: Protected Tree Species (2026)
Key Facts
- Protection ratio
- 70% of significant trees
- Deciduous threshold
- 24-inch diameter breast height
- Evergreen threshold
- 12-inch diameter breast height
- Survey required by
- Certified arborist or forester
- Applies in
- Unincorporated Lake County only
Summary
Development on unincorporated Lake County land subject to site plan review must protect at least 70% of "significant trees", 24-inch-diameter deciduous or 12-inch-diameter evergreen, identified by a certified arborist's tree survey before grading begins.
Significant trees. Significant trees are trees having a diameter breast height (four and one-half feet above average ground elevation) of 24 inches or greater for deciduous trees and 12 inches or greater for evergreen trees. ... At least 70% of all significant trees shall be protected and maintained as permanent open space except those trees that are located within the ultimate rights-of-way of existing roads and existing drainage and utility easements which may be disturbed during construction.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-15: Supplement contains: Local legislation current through Ord. 26-0618, passed 6-9-2026 | State legislation current through ILCS Pamphlet 2025 #5).
Full Breakdown
The Unified Development Ordinance defines a significant tree as having a diameter breast height of 24 inches or more for deciduous species and 12 inches or more for evergreens. A tree survey by a certified arborist or professional forester is required before development, and at least 70% of significant trees found must be preserved as permanent open space, with fencing around drip lines during construction. The Planning, Building and Development Director may approve removal for approved construction plans; removed or damaged protected trees must be replaced with trees of equal combined caliper. Non-native "noxious species" such as buckthorn and box elder get no protection. This chapter reaches only unincorporated county land. Waukegan, Highland Park, Gurnee and other municipalities enforce their own separate tree codes.
Violations & Fines
Removing or damaging protected significant trees without Director approval, or developing inconsistent with the chapter, is a violation under § 151.251, subjecting the property to permit withholding and other enforcement remedies, with each week of an uncorrected violation a separate offense.
Frequently Asked Questions
Does this rule apply inside Waukegan or Highland Park?
Can a protected significant tree ever be removed?
Sources & Official References
Other rules in Lake County
Compare Lake County to another location·View the Illinois tree protection overview
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