SAMP & SEPA

The public comment period on the Port of Seattle’s SAMP Draft SEPA EIS has now closed. Thank you! to every resident, parent, worker, student, organizer, translator, technical reviewer, and community partner who took time to comment, share concerns, and help make this record stronger.

You can still read our community Guide to the SAMP Draft EIS. Sign up for updates!

SAMP: The Port is proposing to expand SeaTac Airport. SAMP is a package of 31 construction projects that anticipates growth to 56–57 million annual passengers by 2032, a ~50% jump in cargo volume, and a roughly ~28% increase in flights.

SEPA: The state-level environmental review process that should examine cumulative impacts on our communities, such as air quality, noise, health, housing pressure, traffic, land use, as well as the broader consequences of an airport expansion program that will shape surrounding neighborhoods for years to come. We will use this page to track what happens next, explain key issues in plain language, and share updates as the Port moves toward its next decision.

The Seattle Space Needle in the background surrounded by buildings and trees.

Status now

August 20, 2026 — Public comment period closed. STACC4J and coalition partners submitted comments on the SAMP SEPA DEIS.

The Port will now review comments and prepare the next step in the SEPA process. It will likely take until the end of the year. Documents to watch for include a Final EIS, revised analysis, or a Supplemental Draft EIS. We are monitoring the Port’s next environmental review steps.

Next update: We will post when the Port publishes comment response materials, announces meetings, releases a revised environmental document, or moves SAMP related decisions forward.

What to watch for

  • Port responses to comments

  • Final EIS or Supplemental DEIS

  • Port Commission briefings or decisions related to SAMP

  • Permit and agency review steps

  • New consultation records, mitigation details, and implementation timelines

what you can do now

1) Sign up for updates! (bottom of this page & the most efficient option) 

2) Read the plain language guide and ask questions.

3) Share the page with neighbors and family.

4) Sign up to track meetings and agency notices at subscribe.portseattle.org/publications (Sustainable Airport Master Plan under the “Environment and Sustainability News” section)

5) Document neighborhood impacts and lived experience. Take pictures, draw a picture, or write a note. Record when you experience something from airport-related good or bad and share it with us!

Common Questions About SEPA and NEPA

  • NEPA is a federal environmental law that requires agencies to study how major projects may affect people and the environment. For airport projects like SAMP, the Federal Aviation Administration (FAA) is the lead agency. The FAA runs the NEPA review and decides whether a project will have significant environmental impacts.

    The FAA completed an Environmental Assessment for the SAMP in 2025. After that review, the FAA issued a “Finding of No Significant Impact” (FONSI), which means they decided the project would not cause significant environmental harm, as long as certain conditions are met.

  • SEPA is a Washington State law. For SAMP and other Port projects, the Port of Seattle is the lead agency for SEPA.  SEPA requires the Port to study possible harms to both the natural environment (air, water, trees, animals, noise) and the built environment (homes, traffic, public services, and community health) before making decisions.

  • SEPA is different because, unlike NEPA, it requires decision-makers to study how a project could affect and possibly harm:

    • The natural environment: air, water, trees, wildlife, and noise

    • The built environment: homes, traffic, public services, and community health

  • SEPA is the chance for Washington State and the Port to go further than NEPA: to look closely at local health, housing, traffic, and economic impacts in airport‑impacted neighborhoods, and to add clear protections, monitoring, and accountability so that future airport growth does not increase harm where people already carry the heaviest burdens.

    SEPA lets the Port, as lead agency, condition, change, or even deny a project based on the environmental information. The Port can require extra protections, monitoring, or changes to design to reduce harm in nearby communities.

    SEPA can—and should—look at how many different pollution and impact sources (airports, highways, rail lines, and warehouses) stack up in the same neighborhoods. It can then require local, community‑driven mitigation to address those combined harms, rather than looking at each project in isolation.