Lake County, IL Tree Protection: Heritage & Protected Trees (2026)
Key Facts
- Significant tree threshold
- 24in DBH deciduous / 12in evergreen
- Required protection ratio
- 70% of significant trees
- Geographic scope
- Unincorporated Lake County only
- Enforcement
- Site development permit review
- Continuing violation
- Each week a separate violation
Summary
Lake County requires developers in unincorporated areas to protect at least 70% of significant trees, defined as 24-plus-inch deciduous or 12-plus-inch evergreen trunks, as permanent open space during site development.
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
Under its Unified Development Ordinance, Lake County defines a significant tree as one with a diameter breast height of 24 inches or more for deciduous species or 12 inches or more for evergreens. Any site development permit application in unincorporated Lake County must protect at least 70% of significant trees on the parcel as permanent open space, with narrow exceptions for trees inside existing road rights-of-way or drainage and utility easements. The rule applies only outside incorporated cities and villages such as Waukegan, Highland Park, and Libertyville, which enforce their own separate codes.
Violations & Fines
Developing without protecting the required 70% of significant trees, or violating permit conditions, lets the Planning, Building and Development Director withhold future permits and pursue civil remedies; each week of an uncorrected violation counts separately.
Frequently Asked Questions
Does this rule apply inside Waukegan or Highland Park?
What exactly counts as a "significant tree"?
Can any significant trees 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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