SEPA Review Threshold Update - What & Why

What Is Happening Now?

SDCI is proposing amendments to the land use code (Title 23) and environmental review thresholds in Title 25 of the Seattle Municipal Code. This means that future new developments would be reviewed less often through the State Environmental Policy Act (SEPA) process. Today’s SEPA review is redundant, since the City’s other code requirements will continue to provide effective protections against environmental impacts. Other Seattle environmental code requirements include drainage review to regulate stormwater runoff and tree protection requirements to maintain and grow our urban forests.

This proposal relates to the City’s Comprehensive Plan update, which defines a new vision for Seattle’s growth. The Plan emphasizes faster delivery of new housing and easier permitting for small businesses.  The streamlining of environmental review will eliminate unnecessary City permitting steps and make it simpler.   

The City’s proposal aligns with state laws and policies that reduce SEPA review requirements. A series of state law updates instead support highly efficient permitting and positive environmental outcomes through rapid provision of new housing and mixed-use developments in urban centers linked by rapid transit.

The City’s proposal 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 more than 65,000 square feet for other non-residential uses.
• These thresholds apply until citywide 20-year growth targets planned in the City’s Comprehensive Plan are achieved. After that, the thresholds would be reset as 200 dwelling units citywide, and 30,000 square feet for non-residential uses.

SEPA review would still be 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 stand-alone parking lots greater than 90 spaces

The amendments will be timely because they set new SEPA thresholds by updating Seattle’s codes to replace the temporary suspension of SEPA review for residential and mixed-use development that was enacted by the state two years ago in SB 5412. This suspension of SEPA review by the state is expiring on September 30, 2025. 

Related Changes

The proposal includes amendments to regulations related to transportation, and cultural resources.  These updates align with the proposed Comprehensive Plan and ensure the City’s codes will continue to result in development that avoids or mitigates impacts. These topics also were studied in the Environmental Impact Statement (EIS) for the Comprehensive Plan, and the proposal responds 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)
• Confirm that construction management plans (CMPs) should be required for certain sizes of new development
• Adjust a transportation impact analysis (TIA) requirement that allows for impact mitigation even if a SEPA review is not performed

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. 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

In September 2025, the SEPA thresholds update proposal will be transmitted to the City Council for review, in two proposed bills.  

• The first bill is for the amendments of the SEPA review thresholds and closely related requirements. 
• The second bill is for amendments related to transportation codes to ensure their alignment with the proposed Comprehensive Plan.

Project Benefits

The proposal 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.
• The proposal supports 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.