Thornton Tree Removal Permit & Ordinance Guide
Adams County, Colorado
Protected Tree Definition
Significant tree: 6 inches DBH or greater on development sites. Public trees regulated by Forestry Division regardless of size. Ash species subject to EAB management.
Protected Species
Heritage / Landmark Trees
Significant Trees defined under Thornton Development Code (Landscape and Tree Preservation) at 6-inch DBH or greater on development sites trigger Tree Preservation Plan review; public trees regulated by Forestry Division regardless of size — Thornton's enhanced-protection tier in lieu of a separate heritage-tree designation.
Permit Requirements
Tree Preservation Plan required during site plan review. Forestry Division approval for public tree work.
Who can apply: Property owner or authorized agent with arborist report
Required Report Sections
Tree inventory with DBH, species, condition, retention plan, mitigation plan
Replacement Requirements
Based on tree size and condition (typically 1:1 to 2:1)
On-site replacement preferred; fee-in-lieu when infeasible.
Fees & Fines
Processing Time
3-6 weeks
Required Certifications
ISA Certified Arborist
Municipal Code
Thornton Development Code (Landscape and Tree Preservation)
View full ordinanceContact
City Development Department / Forestry
(303) 538-7295
Nearby Cities in Adams County
Other Colorado cities
Compare with nearby cities
Data last verified: April 2026. This information is provided as a reference. Always verify requirements directly with Thornton before submitting permits or reports.
Ready to apply? How to apply for a permit in Thornton →
See Colorado replacement obligations compared: How Thornton's replacement ratio ranks in Colorado →
See Colorado heritage criteria compared: How Thornton's heritage designation ranks in Colorado →
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Start your free TRAQ tree risk assessment — designed for Thornton's specific permit requirements.