Seattle's Tree Protection: The Rules That Matter

Every city handles tree protection a little differently. In Seattle, Washington, there are 3 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

Parkway Planting

Seattle requires street trees for any development adding a dwelling unit under SMC 23.44.120.G. SDCI's Director and the Seattle Department of Transportation jointly set the number, species and spacing planted in the right-of-way planting strip, and existing street trees can't be removed without SDOT's approval.

Key details: Trigger: Development adding a principal dwelling unit. Joint authority: SDCI Director with SDOT Director. Existing trees: Retained unless SDOT approves removal. Planting location: Right-of-way planting strip (SMC 11.14.475). If not feasible: 5-ft setback planting or substitute landscaping.

SMC 23.44.120.G is enforced through SDCI's development permit review: plans must show the SDOT-approved street tree count, species and placement before permits are finalized, and removing a retained street tree without SDOT sign-off is a code violation subject to SDCI's standard code compliance process, including correction orders. Replacement planting can be required to bring a site back into compliance before final inspection.

Protected Tree Species

Seattle's overhauled Tree Protection Ordinance, SMC 25.11 (effective 2023), creates a tiered system. Tier 1 exceptional trees, Tier 2 heritage trees, and Tier 3 trees over 12-inch DBH need permits and replacement.

Key details: Code: SMC 25.11 (2023). Tiers: 4 categories. Tier 3 threshold: 12-inch DBH. Replacement cost: $2,833/inch DBH. Authority: SDCI.

Unpermitted Tier 1-3 tree removal: $1,000 base fine plus $2,000 per inch DBH replacement. Tier 1 violation can exceed $50,000. SDCI may revoke development permits for tree-code violations.

This is not one of those rules that cities tend to ignore. Seattle actively enforces its protected tree species requirements.

Heritage & Protected Trees

Seattle designates heritage trees as Tier 1 under SMC 25.11.050 and bars removing or topping them on any lot, developed or undeveloped, unless the tree is hazardous or an emergency action applies under SMC 25.11.030 or 25.11.040. Even when a lot is being developed, Tier 1 trees still cannot be removed for construction convenience.

Key details: Tier 1 trees: designated heritage trees (SMC 25.11.050 Table A). Undeveloped lots: no removal absent hazard, any tier. Developed lots, no permit pending: same removal ban applies. During development: removable only if hazardous or emergency. Approved removal: replacement required under SMC 25.11.090.

Topping or removing a Tier 1 heritage tree outside the hazardous or emergency pathways is a violation of Chapter 25.11 under SMC 25.11.120, triggering a notice of violation, a Director-set civil penalty plus 50 percent, and trebled punitive damages if the removal was willful or aimed at improving views or property value. Criminal convictions carry up to $1,000 and 90 days in jail, rising to $5,000 and 364 days for a repeat violation within five years, plus mandatory site restoration.

This is not one of those rules that cities tend to ignore. Seattle actively enforces its heritage & protected trees requirements.

The Bottom Line

Seattle is tougher than many cities when it comes to tree protection. Out of the 3 rules covered here, 2 are rated strict. If you are a homeowner, renter, or business owner in Seattle, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

These rules come from Seattle's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.