SEPA Review Threshold Update - What & Why

The Seattle skyline with many buildings of differing heights looking south over the freeway.

What Is Happening Now?

On February 18, 2026, Mayor Katie Wilson signed ordinances 127391 and 127392. The ordinances updated SEPA environmental review requirements and related topics, including transportation management requirements and historic and cultural resource protections. They went into effect on March 20.

Following the lead of evolving state policies, this legislation promotes more housing development by significantly streamlining and expediting our permit processes. It does this by eliminating SEPA environmental review for most developments including residential use.

This change will enable many residential and mixed-use developments to skip land use review and apply directly for a building permit. We expect this change to reduce typical residential permitting times by at least 6 months.

The City’s proposal (see the Project Documents page) sets SEPA review thresholds as high as allowed under state law:

Residential development, including mixed-use projects, will not need SEPA review.
Non-residential developments will only be reviewed through SEPA if they have more than 30,000 square feet of retail space or institutional uses, or more than 65,000 square feet for other non-residential uses.
These thresholds apply until citywide 20-year growth targets in the City’s Comprehensive Plan are achieved. If that happens, the thresholds would be reset as 200 dwelling units citywide, and 30,000 square feet for non-residential uses.

SEPA review is still required for certain places and situations, such as:

If the development is over-water in the Shoreline District.
If there is an environmentally critical area (ECA) present, such as wetlands or streams.
New surface parking lots or parking garages with public parking for more than 90 spaces in industrial zones, or more than 20 spaces in other zones, including additions to existing parking uses.

The amendments set new SEPA thresholds to replace the temporary suspension of SEPA review for residential and mixed-use development that expired in Fall 2025.

Related Changes

The ordinances include amendments to regulations related to transportation (see the Project Documents page) and cultural resources (see the attachment in the Director’s Report for threshold changes). These updates align with the Comprehensive Plan and will help avoid or mitigate impacts. These topics also were studied in the Environmental Impact Statement (EIS) for the Comprehensive Plan, and the ordinances respond to the EIS findings and its recommended impact mitigation strategies. These changes are summarized as:

Amended transportation requirements

Simpler, standardized requirements for transportation management plans (TMPs), with simpler thresholds for development size: 75,000 square feet of non-residential uses; 150 hotel rooms, and 250 dwelling units.
Confirmed that construction management plans (CMPs) should be required for certain sizes of new development: greater than 25 dwelling units; 25,000 square feet non-residential use; or needing a shoring permit.
Adjusted a transportation impact analysis (TIA) requirement that allows for impact mitigation even if a SEPA review is not performed. This is required for certain non-residential uses greater than 40,000 square feet in smaller-scale neighborhoods across Seattle.

Amended cultural resource protection requirements

An update to SDCI’s Director’s Rule (DR 2-98) about archaeological and cultural resources, which will be published for public comments at a later date. See the draft edits in an attachment in the Director’s Report for threshold changes. This will increase the City’s consistency with state law to ensure protective requirements for new development sites.
More regulatory protection for “meander line buffer areas” in places where shorelines were previously present, where there is an increased potential for archaeological and cultural resources to be found.

Next Steps

The SEPA thresholds update proposal is now complete, as adopted in Ordinances 127391 and 127392.

SDCI will announce when we publish SEPA-related Director’s Rules for public comment. The rules will address special cases where SEPA review is required, historic and cultural resource protection, and transportation studies.

If you have follow-up questions, please contact Gordon Clowers at gordon.clowers@seattle.gov.

Project Benefits

The ordinances will ensure that the City is maximally supporting the ability for new housing and new business development to occur citywide, while still protecting the environment.

Rapid permitting for housing will provide more affordable housing resources sooner and attract new economic development and employment opportunities.
Supporting the Comprehensive Plan’s vision of vibrant mixed-use neighborhoods and regional centers that are well-served by mass transit service.
Streamlining will help focus permit reviews on what matters, and eliminate unnecessary and unproductive reviews.

The End Result

Seattle will strive to provide a high-quality, livable, affordable, diverse, and dynamic environment for living, working, and recreating.