Seattle Tree Ordinance

Seattle is considering new rules on tree protections which are significantly more restrictive than existing provisions. AIA is seeking member feedback on the draft rules, including how these rules should be prioritized when looking at other city priorities (specifically, housing). We'll use your feedback to help inform our work on these issues.

In February, the Seattle Department of Construction and Inspections (SDCI) and the Office of Sustainability and Environment (OSE) released a draft SEPA ordinance on tree protections. The ordinance would expand the types and sizes of trees that are regulated, require more notice of tree removal, establish payment in lieu of for tree replacement, and more. AIA is seeking member feedback on these provisions, most of which are currently under SEPA appeal.

The below information comes from Councilmember Dan Strauss’ office and this overview document from SDCI and OSE. The document provides additional background information as well as more detail on each of the recommended actions.

SEPA Draft Director’s Report: Tree Protections Update

SDCI and OSE have prepared draft updates to the Land Use and Tree Protection Codes that would implement the strategies from Resolution 31902 (2019) to increase tree protection consistent with the goals and policies of the 20152035 Comprehensive Plan and the 2020 Urban Forest Management Plan (UFMP). This draft legislation would respond to the direction in the resolution from City Council and allow for the expansion of the tree protections by accomplishing the following:

  1. Expand the types and sizes of trees that are regulated, including a new definition of significant trees;
  2. Regulate significant trees 12 inches in diameter and larger;
  3. Simplify provisions, including allowing development standards to be modified to aid in tree preservation as an administrative process without requiring Design Review, while maintaining Design Review as an option in multifamily and commercial zones;
  4. Establish a payment option for tree replacement (payment in lieu);
  5. Support tracking of tree preservation, removal, and replacement; and
  6. Increase penalties for violations of tree regulations.

The draft ordinance and updated business practices fall into these major categories:

  1. Requires tree service providers to register with the City
  2. Prohibits tree service providers who significantly violate tree protections from working in Seattle
  3. Requires public notice for tree removals

These changes are provided for in Council Bill 120207, currently before the Council’s Land Use and Neighborhoods Committee. The language is not part of the SEPA draft.

  1. Limits property owners tree removals to trees under 12” in diameter and establishes property owner self-reporting
  2. Defines significant trees as 6” diameter or greater
  3. Requires replacement of significant trees 12” diameter or greater removed through development
  4. Increases illegal tree removal penalties by 50%

  1. Establishes species-by-species size thresholds for Exceptional Trees (starting at 6” diameter), which cannot be removed in many circumstances
  2. Expands overall Exceptional Tree threshold to 24” in diameter from 30” and add tree groves and heritage trees

Significant trees and tree replacement requirements
The draft ordinance would require any significant tree 12 inches or greater in diameter removed as part of development to be either replaced on-site or mitigated by payment in-lieu of replacement, unless hazardous. This would allow for a property owner to remove up to three smaller diameter trees per year that are under 12 inches in diameter outside of development, which aids and supports a private property owner’s decision such as to have a garden and/or increase solar access.

Tree replacement requirements would continue to be based on the size of the tree removed as well as the proposed payment option. The replacement requirements are:

  • Each exceptional and significant tree that is removed in association with development in all zones shall be replaced by one or more new trees, the size and species of which shall be determined by the Director.
  • The tree replacement required shall be designed to result, upon maturity, in a canopy cover that is at least equal to the canopy cover prior to tree removal.
  • Preference is for onsite replacement. When onsite replacement cannot be achieved, or is not appropriate as determined by the Director, preference for offsite replacement is on public property.

Ecological Function
The draft ordinance would give SDCI arborist staff discretion to evaluate the ecological function of significant trees over 12 inches in diameter and all exceptional trees and potential exceptional trees and determine the likelihood that the trees will live to maturity due to factors including health and physical condition, development site constraints, and environmental conditions external to the development site. Ecological function would be further used to determine whether trees in these two categories would be required to be protected or, if removed, replaced according to the provisions of the tree code.

  1. Charge $436 for removal of significant trees larger than 12” in diameter
  2. Charge $17.87/square inch of trunk for removal of exceptional trees
  3. Payments calibrated to allow City replanting to replace lost tree canopy


SEPA Appeal

The city received a SEPA appeal from the Master Builders Association of King and Snohomish County and several real estate entities challenging items 2-4 above. The appeal challenges the city’s determination of non-significance and seeks to force the city to prepare a full EIS. The Hearing Examiner will take up this appeal, and the City Council cannot consider these three proposals until that appeal is resolved.