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This is STACC4J’s comment for the Port of Seattle SAMP SEPA DEIS. The Port is proposing to expand SeaTac Airport. SAMP is a package of 31 construction projects that anticipates growing today’s ~52.7 million annual passengers to about 56–57 million by 2032, alongside a cargo volume jump of about 75%, and roughly 100,000 additional flights per year — a ~23% increase over the current 435,896 flights.
The DEIS is a report that analyzes the impacts of the airport expansion. Our response comment aims to turn a long technical filing into a plain-language guide so you can see what is at stake, what the Draft EIS misses, and what changes we believe are still required.
Essentially, the DEIS does not give a reliable picture of who will bear the harms of airport expansion. We argue that the review studies too small an area, uses the wrong standard for significance, leaves major health and environmental issues under-analyzed, and fails to fully account for cumulative impacts on already overburdened communities.
If you live in Burien, SeaTac, Tukwila, Des Moines, Beacon Hill, Georgetown, South Park, Federal Way, or nearby communities or have family and friends that do, this page is meant to help you find the parts most relevant to your and your family’s everyday—air, water, noise, housing, traffic, and health concerns.
STACC4J Comments on the Sustainable Airport Master Plan (SAMP) SEPA Draft EIS
August 20, 2026
To: Port of Seattle Commissioners
Steve Rybolt, SEPA Responsible Official, Port of Seattle
samp@portseattle.org
Re: Draft Environmental Impact Statement, Sustainable Airport Master Plan (SAMP) Near‑Term Projects
Coalition signatories: STACC4J, 350 Aviation (contributing partner), Creating Pathways, Duwamish River Community Coalition, King County International Airport Community Coalition, Puget Soundkeeper, Sustainable Seattle.
Commissioners, Mr Rybolt,
The SeaTac Airports Community Coalition for Justice (STACC4J), together with the coalition partners listed above, asks the Port to withdraw and revise the Draft Environmental Impact Statement (DEIS) or issue a Supplemental DEIS before proceeding to a Final EIS. The current document does not give the Port's own Commissioners, the cities living with the airport's operations, or the residents in this coalition a legally reliable picture of who bears the burdens of the SAMP Near-Term Projects.
Most census tracts around SEA already score 7 to 10 on Washington’s Environmental Health Disparities map, with many at 9 or 10. A DEIS that reaches “no disproportionate and adverse effects” on communities the state itself has already identified as carrying disproportionate harm is not a legally reliable picture.
What the DEIS gets wrong, in plain terms:
It draws its map too small. The DEIS studies impacts inside a fenceline drawn close to the airport. The families breathing the diesel exhaust, the schools sitting under the ultrafine-particle plume, the streets carrying the cargo trucks, the creeks receiving the runoff, and the neighborhoods being rezoned to accommodate airport-driven industrial growth all sit outside that fence and inside the pollution. The DEIS treats their reality as somebody else's problem to analyze.
Wrong yardstick. The DEIS declares "no significant impact" when modeled pollution stays below federal ceilings designed to answer a regional-average question. Washington's State Environmental Policy Act (SEPA) asks a different question: does this project add unequal harm to communities already carrying more than their share? The Port answered the regional question and called it an answer to the neighborhood one. The Port itself, in a June 24, 2026 filing before the Seattle Hearing Examiner (W-26-001), endorsed exactly this kind of neighborhood-level analysis for hypothetical future housing in North SoDo. It has not applied that standard to the real neighborhoods around SEA.
The DEIS stays silent on live regulatory frameworks the SAMP will actually be permitted under: the 2024 6PPD-quinone Water Quality Criterion, the 2025 Industrial Stormwater General Permit, the HEAL Act, and Ecology's active air-pollution rulemaking. It is also silent on the permitting-pathway decisions that determine whether meaningful state review happens at all–which Section 404/401 permitting pathway SAMP will use, whether the affected wetlands are still Waters of the United States after Sackett, and where the compensatory wetland mitigation will land (see §3.12.3). Under WAC 197-11-060(5), when a lead agency defers project specific analysis to future permits, it must identify what has been deferred and to which permit. The DEIS does not. A person living under the flight path, sending kids to Highline schools, drinking Highline Water District water, or walking Ambaum or Des Moines Memorial Drive will not find their exposure analyzed in this DEIS.
This letter does not claim the SEPA record is the sole source of authority for downstream permitting agencies. Ecology, the Corps of Engineers, EPA, WDFW, USFWS, NOAA Fisheries, and PSCAA each retain their own independent statutory authority. But the SEPA record is the analytical foundation many downstream decisions are built on, and gaps in the record carry forward into every permit that inherits it.
To meet SEPA's adequacy standard, the Final EIS must do twelve things:
Expand the study area to match the pollution footprint. Analyze the impacts across flight-funnel and freight/cargo corridors, warehouse buildout areas, and the affected watersheds—not just Port-controlled properties. Include Burien, SeaTac, Tukwila, Des Moines, Federal Way, Normandy Park, unincorporated south King County, the Duwamish Valley, Beacon Hill, Georgetown, and South Park.
Analyze cumulative environmental and health impacts using Washington’s environmental justice tools. Integrate the Environmental Health Disparities Map, disaggregate exposure and outcome data by community, and analyze how SAMP interacts with the SR-509 completion, the North of NERA rezone, and the surrounding freight and industrial corridors. SEPA requires cumulative analysis under WAC 197-11-060(4)(d) and WAC 197-11-792 whether or not federal cumulative-impact frameworks apply.
Use significance thresholds calibrated to the neighborhoods, not to regional averages. For air quality, apply Ecology’s proposed screening values under Chapter 173-400 WAC and analyze ultrafine particles (UFPs) — the airport-specific pollutant class small enough to cross from the lungs into the bloodstream, and the pollutant class the DEIS does not analyze. For noise, replace the 1.5 dB DNL threshold with a WHO/EPA population-exposure analysis. For water, apply the 2024 6PPD-quinone Water Quality Criterion, the 2025 Industrial Stormwater General Permit, and the 2024 Stormwater Management Manual.
Disclose the permitting pathway and the post-Sackett jurisdictional analysis. Identify which Sections 404 and 401pathway SAMP will use, whether the affected wetlands remain Waters of the United States. And, if the Port intends to route projects through the Corps under its WRDA arrangement, where compensatory wetland mitigation will land. The location of mitigation determines whether Miller Creek, Des Moines Creek, Gilliam Creek, and the Green/Duwamish receive the ecological functions of what SAMP destroys, or whether those benefits move out-of-basin to the Port’s Auburn “bank.”
Complete substantive government-to-government tribal consultation, and fill Appendix O. The Muckleshoot Indian Tribe, the Suquamish Tribe, and any other Tribes with treaty-reserved resources in the affected watersheds must be engaged under the Governor’s Executive Order 21-02, the Centennial Accord, and the Port’s own MOAs. Publication of a DEIS is not consultation. Appendix O is currently blank and it sits on top of a federal Section 106 record that shows no outreach to the Muckleshoot Indian Tribe..
Identify each analysis being deferred to a downstream permit, and to which permit. Under WAC 197-11-060(5) and WAC 197-11-440(6), the Port must disclose each deferred analysis, which specific permit would address each, the responsible agency, the expected timing, and the regulatory framework that will govern. SEPA-based mitigation cannot rest on undisclosed impacts even as downstream agencies retain their own independent authority.
Attach concrete, funded, enforceable mitigation to each significant impact. Under WAC 197-11-660(1)(b), mitigation must be tied to specific disclosed impacts, matched to the neighborhoods where the impact lands, and include timelines, funding sources, performance standards, public reporting, independent monitoring, and consequences for non-performance. Vague promises are not mitigation.
Where the DEIS falls short
3.1 The Port’s “no significant impact” conclusion is contradicted by…the Port3.2 The Port is grading its own homework
3.3 The Port’s air quality defense rests on standards that are about to change
3.4 The DEIS leaves out ultrafine particles (UFP), possibly the most dangerous pollutant3.5 The noise finding hides behind a 1.5 dB threshold
3.6 Tree canopy loss is treated as insignificant despite direct effects on heat, health, and equity
3.8 The DEIS offloads traffic and roadway safety burdens onto other agencies, cities, and residents
3.9 The displacement analysis stops at the Port fence line even though Cedarhurst residents are being rezoned by a plan the Port helped create
3.9.1 The public process was not a fair proxy for community impact
3.9.2 The final EIS must analyze off‑Port displacement risk
3.10 The jobs analysis counts statewide, not local jobs and that is a SEPA adequacy failure, not a policy gap3.11 The DEIS never mentions the HEAL Act, but Ecology, which will issue SAMP's permits, cannot ignore it
3.12 The DEIS’s water analysis stops at the airport property fence line but water does not.
3.12.1 The existing stormwater infrastructure is already documented as failing
3.12.2 6PPD-Q: the live regulatory framework the DEIS does not engage with
3.12.3 Wetlands
3.12.4 The DEIS does not say which permitting path SAMP will use and that determines whether Washington reviews these projects at all
3.13 The Port already contaminated one drinking-water well with PFAS. The DEIS proposes building on top of another to store SAFs, a fuel chemistry it has not analyzed.3.14 Future permitting cannot substitute for SEPA analysis (including SAFs)
1. Who we are and why we are writing
We are a coalition of community organizations and residents in SeaTac, Burien, Des Moines, Normandy Park, Tukwila, and neighborhoods under the SEA flight paths that include Beacon Hill, Georgetown/South Park, Allentown, and the Duwamish Valley. Our members live and work under constant aviation noise, ultrafine‑particle (UFP) exposure, diesel and toxic tire dust (6PPD-Q) pollution from heavy truck traffic tied to airport cargo and freight, tree‑canopy loss and the rise of heat islands, all leading to alarming health disparities, as well as rising rents and concerns on affordability driven by airport‑adjacent industrial growth.
These comments reflect three years of resident conversations, a 2024–25 working group of 20 grassroots organizations, our 2024 comments on the FAA's NEPA Environmental Assessment for SAMP Near‑Term Projects, community‑led research and collaboration, and commitments made publicly by Port Commissioners and state legislators at the October 17, 2025 Election Forum, and the June 19, 2026 STACC4J-hosted event.
Our core position: The Draft EIS as currently written does not meet SEPA's requirements. Each objection below corresponds to a specific procedural or substantive obligation under the State Environmental Policy Act (RCW 43.21C, WAC 197-11).
2. The Port’s duty to the public, and the Port’s record on it
Before we get to what the DEIS gets wrong, we ask Commissioners to hold four things in view. All four come from the Port's own materials or from Washington state law. All four are already binding on the Port. And all four change what the Final EIS must contain.
Public duty to King County residents. As elected stewards of a public agency and public assets, Port commissioners have a fiduciary duty of care, loyalty, and accountability to the public they serve. That duty includes residents who bear the environmental and health effects of Port operations, not only the economic objectives of cargo and terminal growth.
State law puts pollution reduction inside the Port's mission. RCW 53.08.040(6) authorizes port districts to spend on "programs and activities that are intended to reduce air pollution from vehicles used in cargo transport to, from, and within district facilities" and from cargo vessels, and declares that spending "a governmental and public function, exercised for a public purpose and as a public necessity for promoting cleaner air." The Port's 2015 Century Agenda commits to tripling air cargo to 750,000 metric tons. Every additional container moving between SEA and the warehouses on SR-99 and SR-509 is exactly the "cargo transport to, from, and within district facilities" the statute names. Neighborhood measures like filtered ventilation at nearby schools, off-Port canopy replacement, pedestrian safety on Ambaum and Des Moines Memorial Drive are also within Port authority to fund under the broader "pollution control facilities" language of RCW 53.08.040(1) and the Port's SEPA substantive-mitigation authority under RCW 43.21C.060. For SEA specifically, Chapter 53.54 RCW separately authorizes property acquisition, soundproofing, transaction-assistance, and related noise-remediation programs in impacted areas. State law has already put these measures inside the Port’s authority. When the DEIS treats off-Port mitigation as beyond scope, the constraint is not legal.
The Port's own public health record answers the health question. Public Health – Seattle & King County's 2021 report to the Legislature documents that life expectancy in airport-adjacent communities is two to five years shorter than the rest of King County; hospitalization for heart disease is higher; higher rates of diabetes; mothers in airport communities are more likely to have a premature birth; and noise pollution is linked to poor school performance in children. A Final EIS that reaches a "no significant impact" conclusion while the Port's own website hosts findings like those is not credible.
After the federal review was narrowed; the Port committed that SEPA would fill the gap (SAMP DEIS Chapter 4, §4.3.10). The FAA's NEPA Environmental Assessment for SAMP Near-Term Projects was finalized in September 2025 with a Finding of No Significant Impact (FONSI) after the FAA's Order 1050.1G removed environmental justice, climate change, and cumulative impacts as required areas of analysis. SEPA is a Washington statute (RCW 43.21C). FAA Order 1050.1G does not touch it. When the Port publicly announced the FONSI in October 2025, it stated that the SEPA review would include analyses omitted from the NEPA process, such as “climate, environmental justice, and cumulative impacts." The DEIS must deliver on that commitment.
3. Where the DEIS falls short
3.1 The Port’s “no significant impact” conclusion is contradicted by…the Port
Washington’s Environmental Health Disparities (EHD) map scores every neighborhood in the state from 1 to 10 based on cumulative pollution exposure, health outcomes, and social vulnerability. If your neighborhood scores 9 or 10, you are already carrying environmental and health burdens higher than almost anywhere else in the state. “The project stays under a national average threshold” is not an answer to whether it will make things even worse for you.
Appendix K (Environmental Justice, Socioeconomics, and Children's Health) does two contradictory things. It confirms that most census tracts around SEA score 7 to 10 on the EHD map, with many at 9 or 10. In the same document, the Port then adopts the FAA's EA conclusion that SAMP will cause "no disproportionate and adverse effects" on those communities. But a community at 9 or 10 is by definition already carrying disproportionate harm. Adding a tripling of air cargo, 31 near-term projects, cumulative traffic and warehouse growth, and canopy loss on top of that population and then declaring "no disproportionate and adverse effects" is a conclusion the Port's own facts do not support.
Why this is a SEPA problem, not just a moral one.
Washington's State Environmental Policy Act (SEPA) is broader than the federal thresholds the Port is leaning on. RCW 43.21C.010 states the whole point of SEPA is to "prevent or eliminate damage to the environment and biosphere" while stimulating human welfare. WAC 197-11-448 confirms that federal attainment is a floor, not a ceiling on what SEPA requires. As lead agency, the Port has the authority under RCW 43.21C.060 to condition or reject actions that would worsen conditions in already-overburdened communities, even if the action would technically pass federal numeric thresholds.
The Final EIS must revisit its significance determinations against SEPA's standard, not the FAA's. Where the state's EHD data show communities already at 7 to 10, the Final EIS must treat any additional cumulative burden as significant unless the Port can demonstrate — using independent, community-verified data — that the net effect is neutral or improving for the specific tracts already carrying the heaviest load.
3.2 The Port is grading its own homework
If you wanted to know whether a neighborhood is overburdened, would you trust the answer from the company proposing to expand next to it, or from an independent scorecard? The independent scorecard is the Washington EHD map built for the HEAL Act. The DEIS uses the state EHD map only to describe who lives near the airport. It does not use the EHD map to help decide whether SAMP's impacts are significant.
The Port applies its own Equity Index (PEI, designed by Port staff) co-equally with the EHD map for population screening. The two frameworks weight different factors and use different geographic units (EHD is census-tract, PEI is census-block). Appendix K does not disclose the tracts or blocks where they diverge, or which communities look worse on one and better on the other, or how differences are reconciled.
What the Final EIS must do:
Use the state EHD map and the HEAL Act overburdened-community framework as inputs to the significance determination itself;
Present the EHD map and the Port Equity Index side by side and disclose the census tracts and blocks where the two frameworks produce different overburdened community boundaries; apply the more protective ranking where they conflict; and
Include an "existing knowledge / community override" pathway so that flight-funnel and freight-corridor tracts that fall just outside a threshold are not scored as unaffected when residents' documented experience shows otherwise.
3.3 The Port’s air quality defense rests on standards that are about to change
Ask a resident of Burien and they will say the air near the airport is getting worse. The DEIS says nope. The gap between those two answers is not about the data. It is about which test the Port used.
The test the Port ran is not the test SEPA requires. The federal air-quality test asks a regional question: is the air, on average across a large area, clean enough to meet a national floor? SEPA asks a neighborhood question: does this project add unequal harm to communities already carrying more than their share? The Port answered the regional question and called it an answer to the neighborhood question.
Under WAC 197-11-330(3), a SEPA significance determination has to look at the context and intensity of the impact for the specific community affected, including whether the area is already unusually sensitive and whether approving the project will set a pattern for the next one. The federal National Ambient Air Quality Standards (NAAQS) are a regional attainment test, not a SEPA significance test, and the absence of a federal standard does not equal 'no significant impact.' In other words, if SEPA’s question is, "Will this hurt Boulevard Park or Beacon Hill?" and the DEIS's response is, "Regional air quality still meets federal standards," that does not answer the question.
The Port's own numbers show why the neighborhood question matters. DEIS Chapter 4, Table 4.3.1-10 reports how much air pollution the project would add. For nitrogen dioxide (NO₂, a traffic and jet engine pollutant tied to asthma and lung disease) the project adds a peak of 22 micrograms per cubic meter over one hour or nearly 3x Ecology’s screening value, the amount big enough to trigger a closer look. For fine particulate matter (PM2.5, tiny particles that lodge deep in the lungs and are linked to heart disease and premature death) it adds 0.5 micrograms per cubic meter as a yearly average–almost 4x Ecology’s screening threshold.
Those thresholds are permitting screens, however, not SEPA significance tests. An EIS that never engages with the size of its own reported increment is not a significance analysis. It is a federal attainment check. The DEIS makes this clear: page 4-9 states that "the total concentrations (increment plus background) were then compared to the NAAQS to determine if an impact could occur." Table 4.3.1-10 executes exactly that test — its rightmost column is titled "Exceed NAAQS?" and every row answers "No." That is the only significance test the table performs. Under WAC 197-11-448, that is not enough.
Two more things the DEIS record does not show. First, EPA tightened the federal PM2.5 standard in 2024 — from 12 down to 9 µg/m³. Any Ecology permit issued during SAMP construction will be issued under the tighter number, not the number the DEIS modeled against. Second, the Port has already told a court exactly what airport-adjacent housing suffers from.
On June 24, 2026, the Port filed a motion before the Seattle Hearing Examiner (File W-26-001) opposing a City of Seattle plan that would have allowed new housing near industrial and freight operations. The Port argued that mixing homes with "active industrial and freight corridors" would cause "truck traffic, rail and port operations, nighttime activity, noise, emissions, safety, and pressure to limit or modify industrial operations." The Port told the court these concerns were "not academic, theoretical, or hypothetical."
Read that list again. It is exactly what residents of Burien, SeaTac, Des Moines, Tukwila, and unincorporated King County already live with every day because of the airport, SR-509, and the freight corridors the SAMP will help expand. The Port applies one standard to protect an industrial area from hypothetical future housing. The DEIS applies a much weaker standard to protect actual neighborhoods where people have lived for decades. The impacts are the same. The people are different.
3.4 The DEIS leaves out ultrafine particles (UFP), possibly the most dangerous pollutant
If you live under the flight path, the particles you cannot see are more dangerous than the ones you can. Ultrafine particles (UFPs) of pollution are so small it passes straight through lung tissue into the bloodstream. Peer-reviewed research strongly links them to cancer, heart disease, and lung disease near this airport. The DEIS does not analyze them.
The federal environmental assessment did not analyze ultrafine particles, and the SEPA DEIS didn’t either. Appendix C states the Port's position plainly: because UFPs are not regulated by EPA or the state and are "a subset component of PM2.5," they were not typically considered in formal reviews. This claim does not survive contact with science. PM2.5 is a mass-based standard. Ultrafine particles are so much smaller than PM2.5 sized particles that they contribute negligibly to total particulate mass even when present in large numbers.
Picture a bathroom scale. Put a single grape on it and the needle moves; pour a teaspoon of powdered sugar on it and the needle barely twitches, even though the sugar contains billions more particles than the grape. Mass-based air quality monitoring works the same way; it weighs what is in the air, so a small number of larger particles registers while an enormous number of ultrafine particles (the sugar) does not. Ultrafine emissions can rise sharply without moving the PM2.5 mass metric at all. That is why UFPs are not captured by mass-based standards and are not currently regulated by EPA and why a monitor that reads "clean" by PM2.5 can still be carrying hundreds of thousands of ultrafine particles per cubic centimeter from jet exhaust.
The absence of a numeric ambient standard for UFP is not a defense. Under WAC 197-11-448 the absence of a federal standard does not equal "no significant impact." Under WAC 197-11-330(3)(e) the character of the affected environment, including documented UFP-linked disease clusters in this airshed, belongs inside the SEPA significance determination.
The University of Washington MOV‑UP study (2017) documented a distinct aircraft-related ultrafine particle signature over communities under and downwind of landing jets at SEA measurably different in size and composition from roadway-traffic particles, with highest concentrations under the landing paths.
The UW Healthy Air Healthy Schools project (2021) found that in five schools near SEA, approximately 54% of outdoor ultrafine particles were measured inside classrooms before intervention, and approximately 9% after portable HEPA filters were installed — an 83% removal efficiency for total UFPs and 67% for aircraft-specific particles. Direct evidence both of impact and of a feasible mitigation.
A 2014 peer-reviewed study of LAX found that UFP number concentrations downwind of the airport were roughly doubled as far as 10 miles downwind, with 4x to 5x increases extending 5 to 6 miles and roughly 10-fold increases within 3 kilometers. Direct evidence that this DEIS's study area is drawn too small. UFP plumes extend well beyond the airport fence line.
The HB 1109 report to the Legislature and the underlying 10‑mile analysis document elevated asthma, COPD, heart disease, stroke, and diabetes rates within ~10 miles of SEA and call for investments in green space and air‑filtration.
King County already responded to this evidence by distributing thousands of air purifiers to households near airports and funding an Airport Air Quality and Asthma Community Health Worker Program.
The final EIS must include a UFP analysis using UW MOV‑UP data, Ecology and PSCAA monitoring, and community‑generated data, because a "no significant impact" finding that omits the pollutant class most tied to documented local harm is not credible.
3.5 The noise finding hides behind a 1.5 dB threshold
Ask any resident near the flight path whether the noise has gotten worse, and the answer is not measured in decibels; it is measured in interrupted sleep, kids who cannot hear a teacher, and conversations paused mid-sentence when a jet passes overhead. When a plane flies overhead, noise rises to a peak, then falls back to the background between planes. As more planes fly, the peaks come closer together and the quiet stretches between them (where you can have a normal voice conversation) get shorter and rarer. The Port's noise metric averages all of that across 24 hours, so a big change in how often the peaks occur can hide inside a small change in the average on paper.
Appendix J acknowledges that aircraft noise can cause annoyance and disturb sleep, but concludes "no significant noise impact" because the modeled increase is less than 1.5 dB at noise sensitive land uses within a 65 DNL contour. Aside from impacts hidden by averages, that framing hides two facts established in the record:
More homes, residents, schools, and other noise‑sensitive facilities end up inside high aircraft‑noise contours under the Proposed Action. A widened contour that pulls new households into 65 DNL is a real added burden, not a null result.
The FAA Neighborhood Environmental Survey has already shown annoyance and sleep disturbance dose response curves are far worse than the older assumptions the Port is using.
The 65 DNL threshold the DEIS relies on sits above every health-based standard the public record identifies. EPA has determined that safe noise levels are 45 dB DNL for indoor and 55 dB DNL for outdoor exposure. The WHO recommends aircraft noise stay below 45 dB averaged across day/evening and below 40 dB at night.
The health evidence at the levels this airshed actually experiences is strong: a multi-airport study of over 6 million Medicare recipients found higher cardiovascular hospital-admission rates near airports; a Zurich case-crossover study of 24,886 cardiovascular deaths linked nighttime aircraft noise directly to fatal heart attacks; the Münzel et al. review in the Journal of the American College of Cardiology concluded the cardiovascular effects of transportation noise meet the Bradford Hill criteria for causality; and a Swedish longitudinal cohort study (2024) links long-term aircraft noise exposure to faster global cognitive decline. The FAA-funded hypertension studies Appendix K cites as "statistically marginal" are not the state of the science.
The final EIS must replace the 1.5 dB significance test with a population exposure analysis that reports (a) the change in number of homes, residents, schools, and child‑care sites inside 55, 60, 65, and 70 DNL contours; (b) sleep disturbance and hypertension exposure using current dose‑response curves; and (c) the cumulative burden in tracts already at EHD 7–10.
3.6 Tree canopy loss is treated as insignificant despite direct effects on heat, health, and equity
Trees are not decoration in our neighborhoods. They stand between residents and dangerous heat. The 2021 Pacific Northwest heat dome killed at least 100 people in Washington, and King County identifies low canopy cover in South King County as a driver of that. They are also one of the few tools that filter diesel exhaust before it reaches a bedroom window. The DEIS acknowledges tree removal on a large scale and still concludes it does not matter.
Appendix K §6.3.4.2 states that approximately 56.4 acres of trees, shrubs, and vegetation would be cleared for SAMP off-site cargo (C02), parking, and Westside Maintenance projects. It acknowledges that urban tree canopy is a Port Equity Index indicator and still concludes no significant adverse environmental justice impact.
Canopy loss compounds a heat island effect this region already has. King County and the City of Seattle's 2020 heat-mapping study found that two people standing in different parts of King County at the same hour can experience as much as a 20-degree Fahrenheit temperature difference, driven largely by land cover: pavement, industrial activity, and missing tree canopy. Climate Central's regional analysis, reported in the Seattle Times, found that hotter neighborhoods are disproportionately home to people of color, and that the heat extends from the Duwamish through Tukwila and along the corridor toward Tacoma—the same warehouse and cargo corridor that SAMP will help expand.
Heat and air pollution do not just add — they compound, partly because pollution is trapped closer to where people breathe and sleep. A 2023 study of 620 cities across 36 countries found that mortality risk from a heat wave roughly doubles on high-pollution days: heat-attributable death rates rose from 5.3% when PM10 was low to 12.8% when PM10 was high. A 2025 Thailand study confirmed the same pattern for PM2.5, NO₂, and ozone, and found specifically that higher green density mitigates the combined effect.
The Port then deepens the omission. The same DEIS chapter reports that diesel and fine-particle pollution will stay under national standards and calls that "no significant impact" even as those are exactly the pollutants that get worse when the SAMP removes canopy, adds pavement, and adds warehouse-corridor truck traffic.
King County has put its policy on the record. Its 2024 Extreme Heat Mitigation Strategy commits to protecting and increasing green space "especially in heat islands" and to concentrate investment in "communities disproportionately impacted by climate change." Its 30-Year Forest Plan directs canopy investment to places and communities with “residential areas subject to high levels of summer heat and/or pollution or other human health disparities." The SAMP proposes to do the complete opposite in the same places.
A UW study found that urban residents in Seattle and along the I-5 corridor face elevated relative risk for heat-related illness during heat waves, and tree canopy is one of the strongest neighborhood-scale protective factors against that risk. Canopy loss in already-hot, already-burdened tracts is two steps backward.
The Final EIS must (a) analyze net canopy change by census tract and EHD score, not just in aggregate, and overlay the results on King County's heat mapping data so decision makers can see whether canopy is being removed from tracts already identified as heat islands; (b) commit to 1:1 or better replacement canopy within the same overburdened tracts, on a timeline that recognizes new trees take decades to deliver full cooling and filtering benefits; and (c) publish canopy change over time in those tracts, aligned with the reporting cadence of King County's Extreme Heat Mitigation Strategy.
3.7 The Port has already written the cumulative-impact checklist for the communities around SEA. It just wrote it for a different neighborhood.
Imagine three different construction crews digging next to your house, each one telling you their own project "isn't that bad" while ignoring that all three combined are what is actually making your street impassable and your air unbreathable. That is what is happening here. SAMP cargo growth, the SR-509 freeway extension, a regional warehouse boom, and a residential rezone next to the airport are all landing on the same neighborhoods at the same time, but the DEIS reviews each one as if the others did not exist.
This bears repeating. In its June 24, 2026 filing before the Seattle Hearing Examiner (File W-26-001), the Port listed the impacts it said had to be analyzed together when residential uses sit near industrial and freight operations: "truck traffic, rail and port operations, nighttime activity, noise, emissions, safety, and pressure to limit or modify industrial operations." It describes exactly what residents of SeaTac, Seattle, Burien, Tukwila, Des Moines, and unincorporated King County already live with every day because of the airport, and that SAMP will increase. It is the cumulative burden this DEIS declines to analyze.
The Port also told the hearing examiner what the remedy is when a SEPA document does not adequately address these combined impacts on residential communities: a supplemental environmental impact statement. The Port cannot argue that a supplemental EIS is the right SEPA tool when housing near industrial operations is hypothetical in North SoDo, and then turn around to argue that no cumulative analysis is even needed here, where the housing has been there for decades.
SEPA is explicit on three points the DEIS ignores:
Several marginal impacts "when considered together may result in a significant adverse impact" (WAC 197-11-330(3)(c)).
A lead agency "shall not limit its consideration of a proposal's impacts only to those aspects within its jurisdiction, including local or state boundaries" (WAC 197-11-060(4)(b)).
A proposal's effects include "those effects resulting from growth caused by a proposal, as well as the likelihood that the present proposal will serve as a precedent for future actions" (WAC 197-11-060(4)(d)).
The DEIS uses numbers to describe impacts throughout the document. For cumulative impacts, it offers words instead of numbers. It does not add the Near-Term Project elements to one another. It does not add them to the stack of pollution, noise, and health burdens these communities already carry. And it treats the off-Port warehouse and freight growth this project will induce as someone else's responsibility.
The Final EIS must do:
Analyze SAMP cumulatively with the SR-509 Completion.WSDOT describes SR-509 as "one of the Puget Sound region's most critical freight corridors to the ports of Tacoma and Seattle and Seattle-Tacoma International Airport." The DEIS treats it as a "separate project," but SAMP cargo growth (C02, C03), SR-509 freight capacity, and warehouse growth are functionally the same system landing on the same neighborhoods. The DEIS treats SR-509 as a "separate project"; SEPA does not.
Analyze SAMP cumulatively with the warehouse and logistics boom SAMP cargo demand is driving. The King County Assessor's 2024 commercial report calls warehouse space in the county "a prime, sought-after real estate investment class" with year-over-year rent growth +30% in Puget Sound. An example the DEIS ignores include the ~1 million sq ft warehouse planned for the former Wild Waves site in Federal Way, and growing regional truck volumes on I-5, SR-509, and SR-167.
Analyze SAMP cumulatively with the North of NERA / Cedarhurst rezone. The City of Burien's own FAQ acknowledges the rezone is meant to support "employment and industrial opportunities" in proximity to the airport in a currently residential area, and the Burien’s Community Development Director frames the same footprint. Residents launched a petition opposing rezoning of homes in Boulevard Park, and the Cedarhurst Neighborhood is organizing on this issue directly. The DEIS declares this "outside the SAMP scope" — but the Burien Comprehensive Plan was created in partnership with the Port of Seattle, and SAMP cargo demand is the economic driver.
Analyze SAMP cumulatively with existing environmental burdens on these communities. These include Superfund and Model Toxics Control Act (MTCA) sites, PSCAA- and Ecology-monitored air quality baselines, existing highway noise from I-5 and SR-509, and existing urban heat islands documented by King County Public Health and the University of Washington.
Analyze the trucks, freight, noise, emissions, nighttime activity, and safety impacts on these communities together as one combined burden landing on one set of neighborhoods the way the Port itself has said SEPA requires when housing sits near industrial operations. Anything less applies one standard to hypothetical residents in North SoDo and a lesser one to the real residents who have been carrying the actual burden of airport operations for a generation.
3.8 The DEIS offloads traffic and roadway safety burdens onto other agencies, cities, and residents
Ask a parent in Burien which streets they will not let their kids bike on, and Ambaum, 128th, and Des Moines Memorial Drive come up. Residents flagged these as unsafe to walk long before any of this project's cargo trucks were added. Ask a driver near the airport which intersections already back up worst, and several of them are ones the Port says are somebody else's problem to fix. Hot potato is not a solution—it leaves residents stuck with roads that are dangerous for both cars and pedestrians, and it leaves cities paying to accommodate cargo growth the Port drives.
The DEIS studies delay for cars. It does not study safety for people. It models how long vehicles wait at intersections. It does not model whether a person on foot or a bike can safely cross the street. It does not analyze the combined SAMP + SR-509 + warehouse-freight impact on local roads, nor does it identify who pays for the extra road maintenance from heavy Port-serving traffic, and evaluates no alternatives that route freight away from residential streets.
Eight of the worst intersections get no fix at all. The SEPA EJ Memo reports that the Action Alternatives worsen delay at 26 intersections. 18 receive mitigation. Eight WSDOT-controlled ramps and intersections receive none, even though they are "high-volume roadways." Leaving eight high-volume locations unmitigated because they are in another agency's jurisdiction is not mitigation; it is jurisdictional deflection. The DEIS also frames the added delay as "slight" under both No Action and Action Alternatives without separating background growth from project-caused traffic, which lets the Port hide the marginal contribution of SAMP.
The cost transfer to cities is already happening. The City of Burien is investing in multi-million-dollar infrastructure upgrades along South 140th and Des Moines Memorial Drive under a joint City-Port plan explicitly aimed at supporting “triple air cargo volume; triple value of outbound cargo.” Burien residents are paying, through their own capital budget, for infrastructure that serves Port cargo throughput while also absorbing the safety, noise, and displacement impacts. The DEIS does not disclose this cost transfer.
What the Final EIS must do:
Identify the eight unmitigated WSDOT-controlled intersections and disclose whether the Port has asked WSDOT to mitigate the eight intersections, the date of that request, and WSDOT's response if one has been received; if no request has been made, state that plainly and identify the trigger that would prompt one.
Model pedestrian and bike safety, not just vehicle delay, on Ambaum, 128th, Des Moines Memorial Drive, and every other residential street the Port's projected freight will travel.
Analyze the combined local-street freight burden of SAMP + SR-509 + regional warehouse growth, not each in isolation.
Disclose the roadway cost transfer to Burien, SeaTac, Tukwila, Des Moines, and other affected cities, and identify who will pay for each element of the resulting road maintenance and safety mitigation.
Evaluate at least one alternative that routes freight away from residential streets.
Separate background traffic growth from SAMP-caused traffic in every delay figure, so residents and decision-makers can see the marginal contribution of the project itself.
3.9 The displacement analysis stops at the Port fence line even though Cedarhurst residents are being rezoned by a plan the Port helped create
Down the street from the airport, in the Boulevard Park / Cedarhurst neighborhood of Burien, roughly 247 homes on 265 lots are being rezoned out of a residential neighborhood to accommodate airport-compatible development. After a February 2026 resident petition drew over 850 signatures, Burien wrote the current draft to preserve residents' code-level rights: existing homes remain a conforming use, homes may be maintained, remodeled, expanded, and rebuilt if damaged, and one ADU is allowed. But without sustained organizing, residents would have faced the full weight of a residential-to-industrial rezone with no carve-outs: no extension of the residential use, no additions, no rebuilding after damage above 50-75% of value, and loss of the use if it lapses.
Those wins matter, and they do not close the SEPA gap. The ordinary things that make a house a stable place to live are governed by more than the code. Lenders decide whether to refinance a home surrounded by industrial parcels. Insurers decide what it costs to keep coverage next to warehousing and freight uses. Appraisers and buyers decide what the house is worth on the next sale. None of those actors are bound by Burien's promise that the home remains a conforming use. Rebuild rights on paper do not equal the ability to rebuild once industrial-zone setbacks, landscaping, and FAA-compatibility conditions apply. No new single-detached homes can be built after adoption, and there is no buyout, relocation assistance, or Community Benefits Agreement on the table for the residents who cannot afford to move (Cedarhurst Neighborhood; Highline Journal, April 25, 2026). The market, not the code, decides what a house inside an industrial patchwork is worth to the next lender, insurer, or buyer.
Nutshelled, the rezone is not a city matter that just happens to be located near the airport. The City of Burien's NERA page states: "In 2010, the City of Burien, in partnership with the Port of Seattle, completed a Redevelopment Plan and Implementation Strategy for Burien's 135-acre Northeast Redevelopment Area." The 2026 rezone implements that plan. The July 22, 2026 draft ordinance states that the new zone is intended to "facilitate economic development and provide flexibility for airport-compatible uses" and that "use and development within this zone may be affected by FAA regulations associated with SEA operations." The SAMP planning materials in turn treat SAMP cargo growth as depending on off-Port industrial capacity of exactly the kind this rezone enables. The DEIS cannot treat this as unrelated.
Appendix K concludes that SAMP will not significantly worsen displacement risk or housing affordability, because most direct land-use changes are on Port-controlled property. The DEIS reports one displaced business (Doug Fox car rental) and stops there.
The off-Port record contradicts this. The South King County Housing Action Plan documents that Auburn, Burien, Federal Way, Kent, Renton, and Tukwila "have experienced rising rents and displacement pressure." Cascade PBS reports displacement pressure in unincorporated North Highline and Skyway-West Hill and the loss since 2012 of 112,000 housing units affordable at 80% AMI or below. In South King County nearly 60% of renters are cost-burdened, well above the county average. The King County Displacement Risk Map shows greater displacement risk across the study area. SEPA's housing checklist guidance confirms lead agencies can and should analyze off-site housing impacts when a project drives them.
In its June 24, 2026 filing in Seattle Hearing Examiner File W-26-001, the Port identified as a SEPA harm the removal of "existing protections intended to separate residential uses from major truck streets and industrial operations." That is exactly what is happening in Boulevard Park.
3.9.1 The public process was not a fair proxy for community impact
The June 10, 2026 Burien Planning Commission hearing followed a standard municipal format: a lengthy staff and consultant presentation, followed by Commission questions, followed by public comment at the end of the meeting. Residents brought substantive, expert-level testimony on the rezone’s airport, environmental, and public health implications. Under the hearing’s structure, that testimony was received into the record but did not become the subject of Commission deliberation before the vote. This is not unusual — it is how most municipal planning hearings are structured — but it is exactly why “no municipal-stage objection” is not a reliable proxy for community impact.
That structural limit falls unevenly. The residents who did reach the microphone had the resources this process requires: time off work, written testimony prepared in advance, and door-to-door outreach capacity. Latinx, East African, Chinese, Lao, and Khmer neighborhoods carrying comparable or greater cumulative burdens have far less realistic access to a hearing designed this way — in-language materials, evening timing, childcare, translation at the podium, and a comment structure that treats community testimony as evidence to be weighed rather than input to be filed. A SEPA analysis that reads a unanimous municipal recommendation as evidence of no impact is measuring who reached the microphone, not who is being harmed — the exact gap the HEAL Act framework and Environmental Health Disparities map are designed to catch (see §3.2, §3.11).
3.9.2 The final EIS must analyze off‑Port displacement risk
—rent pressure, housing insecurity, cultural and small business displacement—and treat neighborhoods that are both high-EHD and at high displacement risk as priority cumulative impact zones. Those zones warrant concrete, funded mitigation: buyout, relocation assistance, or a Community Benefits Agreement tied to the neighborhood absorbing the impact.
The Port cannot demand cumulative analysis of a hypothetical loss of buffer in North SoDo while disclaiming any obligation to analyze the actual loss of buffer in a neighborhood next to its own airport. Municipal-stage public engagement is not a substitute for that analysis.
3.10 The jobs analysis counts statewide, not local jobs and that is a SEPA adequacy failure, not a policy gap
Once the DEIS claims employment as a positive impact, it opens a SEPA element that the analysis has to include. Employment is one of the "elements of the environment" listed in WAC 197-11-444. Under the HEAL Act, RCW 70A.02.060, covered agencies are required to assess how environmental and health impacts, including benefits, are distributed across overburdened communities and vulnerable populations. Ecology's SEPA Handbook treats disproportionate distribution of benefits and harms as a required part of cumulative impact analysis. A statewide aggregate cannot answer a distributional question, which is basically what the DEIS has done here.
The Port touts the tens of thousands of jobs that airport growth supports across Washington. The Port business lines "supported almost $39 billion in total business output, over 205,000 total jobs, and $396 million in total fiscal impact". That is a true statewide number and a useless local one. It does not tell a resident of SeaTac, Burien, Des Moines, or Tukwila how many people in their city actually hold one of those jobs, at what wage, in what occupation, or with what barriers exist. The DEIS provides no ZIP code level, race, or equity breakdown of who gets airport-adjacent jobs and contracts, and it identifies no binding equity or workforce commitments tied to SEPA findings aside from aspirational language about OEDI and workforce programs.
The Final EIS must do: (a) report jobs and contract data by airport-impacted ZIP codes and by race, language, and gender—the disaggregation the HEAL Act's distributional-analysis requirement expects and builds in; (b) analyze the access barriers residents actually face—language, credentials, transportation, application complexity—because a benefit a resident cannot reach is not a benefit the DEIS may count; and (c) treat fair access as SEPA mitigation, with concrete, funded, measurable commitments tied to the SEPA record, not as separate voluntary programs the DEIS references but does not bind.
3.11 The DEIS never mentions the HEAL Act, but Ecology, which will issue SAMP's permits, cannot ignore it
Washington's Healthy Environment for All Act (HEAL Act, RCW 70A.02) requires certain state agencies to weigh environmental justice before taking actions that affect communities already carrying more than their share of pollution. The Port of Seattle is not one of those agencies, and the DEIS uses that fact to explain why it does not analyze SAMP through a HEAL Act lens. The Port is procedurally correct about its own status. It is not correct about what happens next. SAMP cannot be built without approvals from the Washington Department of Ecology, and Ecology is a HEAL Act covered agency whose obligations the DEIS never engages.
Before SAMP Near-Term Projects can begin, Ecology must issue or act on multiple approvals: the Construction Stormwater General Permit, Section 401 Water Quality Certification, coverage under the Industrial Stormwater General Permit, and Underground Storage Tank notifications. Each of these is a "significant agency action" under RCW 70A.02.060, which requires Ecology to conduct an environmental justice assessment before it acts. Ecology has already acknowledged this obligation. In its June 2026 rulemaking bulletin on the "cause or contribute" threshold values that govern permitting of new and modified air pollution sources, Ecology states, "This rulemaking will include an environmental justice assessment, as required by the HEAL Act."
The Port's silence on all of this is not a legal defense. It is a timing bet. The DEIS relies on air quality thresholds Ecology is in the middle of revising, and Ecology has stated that any permits it issues will be governed by the thresholds and environmental justice framework in effect at the time of issuance, not the thresholds the DEIS modeled against. The Port is proceeding anyway, betting that a SAMP analysis calibrated to yesterday's thresholds will hold up under whatever framework Ecology applies tomorrow — and against a growing state and federal record on this airshed's actual exposure burden that the DEIS never cites.
That evidence is not obscure. It is the state and federal record telling Ecology, on multiple channels, that this airshed warrants closer scrutiny:
Ecology's proposed screening values under WAC 173-400-113 Table 4a — which the Port's own reported project increments exceed by roughly 3× for NO₂ and 4× for PM2.5 (see §3.3).
The University of Washington MOV-UP study, documenting elevated ultrafine particle exposure in the communities under and around SEA.
EPA's 2024 revision of the fine-particulate NAAQS from 12 to 9 µg/m³ — a tighter federal ceiling the DEIS did not model against.
The Washington Department of Health's Environmental Health Disparities map, which scores the same neighborhoods under SEA's flight paths at 9 and 10 out of 10.
When Ecology acts on SAMP's stormwater permits, its Section 401 certification, and other approvals, it will do so under its own HEAL Act obligations, applying the thresholds, cumulative impact analysis, and environmental justice framework in effect at that time, not the framework the DEIS modeled against.
What the Final EIS must do:
Identify each state and local approval required for SAMP Near-Term Projects and the agency responsible.
Under SEPA's phased-review provisions (WAC 197-11-060(5)), disclose which analyses the Port is deferring to which permit and on what timeline. If the Port intends to defer 6PPD-Q loading analysis to the Industrial Stormwater General Permit, PFAS characterization to the Section 401 certification, and cumulative air-quality significance to permit-stage modeling under Chapter 173-400 WAC, it must say so on the record.
Name the applicable regulatory frameworks the Port will be permitted under: the HEAL Act (RCW 70A.02), the 2024 6PPD-Q Human Health Water Quality Criterion, the 2025 Industrial Stormwater General Permit, the Phase I and Phase II Municipal Stormwater Permits governing the discharging jurisdictions, and the 2024 Stormwater Management Manual for Western Washington.
Provide the environmental-justice data Ecology needs for its rulemakings and permit decisions including per-community cumulative exposure levels and EHD inputs, and commit to producing any additional analysis Ecology identifies as missing during permit review.
3.12 The DEIS’s water analysis stops at the airport property fence line but water does not.
Every new acre of pavement at the airport sends rain, fuel residue, de-icing chemicals, and tire dust somewhere. The Port’s own documents identify where: SEA discharges to Lake Reba, Miller Creek and its West Fork, Walker Creek, Northwest Ponds, Des Moines Creek, Gilliam Creek, and Puget Sound. Gilliam Creek is the airport’s hydrologic connection to the Green/Duwamish, and the DEIS itself places the airport in the “Gilliam Creek / Lower Green River” drainage basin (Chapter 3, p. 3-97). Yet the DEIS’s water analysis does not trace where that water actually goes, or reach the drinking-water aquifer beneath its expanded fuel farm, the neighborhoods SAMP will reshape, and the salmon streams that run through them.
The North of NERA area — treated by the Port as outside SAMP scope but planned for airport-compatible warehouses and industrial buildings to function as part of SAMP’s foreseeable freight and cargo growth — sits on top of a protected drinking-water source. Officially designated as a Critical Aquifer Recharge Area (CARA) under Burien Municipal Code 19.40.420, it is a piece of land where rainwater soaks down into an underground aquifer a community uses for drinking water. What lands on the surface can end up in someone’s tap water.
The aquifer is the Vashon Advance Outwash aquifer (Qva), an active daily drinking-water source across the Highline area. The Highline Water District, which serves much of Burien, SeaTac, Des Moines, Tukwila, and unincorporated King County, draws roughly a quarter of its daily drinking water from three active Qva wells (Des Moines, Angle Lake, McMicken). The rest is purchased from Seattle Public Utilities' Cedar River supply. Seattle Public Utilities separately draws on the same Qva aquifer at its Riverton and Boulevard Park wellfields in SeaTac—three wells that can supply up to 10 million gallons per day as peak-season and emergency supply for the wider Seattle system. On Vashon-Maury Island the same Qva unit is a federally-designated Sole Source Aquifer under Section 1424(e) of the Safe Drinking Water Act, meaning EPA has found no reasonably available replacement if it is contaminated. The Final EIS should identify the relevant aquifer units, recharge areas, confining conditions, wellhead-protection areas, and travel pathways, rather than assume either complete vulnerability or complete protection. A DEIS that touches this aquifer with pavement, cargo lots, warehousing, and de-icing runoff owes the record more than a general statement that “confining layers” exist.
A note about recharge and current water supply conditions. This aquifer recharges with rain. Also, rain falling north of NERA drains into the West Fork of Miller Creek — a Type 2 trout-bearing stream identified by the City’s consulting engineer, OTAK— which flows into the main stem of Miller Creek, the same creek restored with contributions from Burien, SeaTac, Ecology, and the Port. Neither the CARA nor the Type 2 stream appears anywhere in the DEIS as an affected environmental feature, even though runoff and absorption, groundwater movement and quantity, and fish habitat are all elements of the environment the Port is required to analyze.
Appendix M quantifies a net increase of 74.43 acres of impervious surface, then provides no estimate of the resulting reduction in aquifer recharge, a gap EPA also flagged. The infiltration best-management practices (BMPs), such as facilities that route stormwater into the ground, are deferred to later design and limited by the Port’s own Infiltration Infeasibility Map. Without quantifying either the recharge loss from 74.43 new impervious acres or the recharge the eventual BMPs would restore, an unquantified impact cannot be shown as offset by an equally unquantified mitigation measure.
This matters now because the rain doing the recharging has become unreliable. Ecology has declared drought for four consecutive years, citing multi-year precipitation deficits. Less infiltration and faster runoff together can reduce summer base flow and contribute to warmer stream conditions where cutthroat trout live – effects the final EIS should quantify for the West Fork and main stem of Miller Creek.
What the Final EIS must do:
Quantify the aquifer recharge reduction resulting from the 74.43 acres of net new impervious surface identified in Appendix M, by sub-basin, and disclose the resulting change in Qva recharge volume, runoff, and summer base flow — the gap EPA identified and the DEIS did not close.
Analyze the Burien Critical Aquifer Recharge Area and the West Fork of Miller Creek as affected elements of the environment under WAC 197-11-444 — runoff and absorption, groundwater movement and quantity, and fish habitat — neither of which appears anywhere in the DEIS.
Disclose the drinking-water systems and wells drawing from the Qva, including Highline’s Des Moines, Angle Lake, and McMicken wells and Seattle Public Utilities’ Riverton and Boulevard Park wellfields, and analyze SAMP’s effect on each, including any interaction with the open Ecology PFAS cleanup sites at SeaTac Airport (CSID 17061) and Boulevard Park Well (CSID 17323), given the 2022 Tyee-well contamination and 2024 Highline settlement.
Analyze recharge and base flow under current drought conditions as baseline rather than historic normals. Ecology has declared drought for four consecutive years, and the April 8, 2026 declaration covers every watershed in the state, citing multi-year precipitation deficits.
Quantify any infiltration BMP credit claimed against recharge loss, including which SAMP project sites fall inside the Port's Infiltration Infeasibility Map, the design infiltration rate and tributary area for each proposed facility, and the residual recharge deficit after mitigation — unquantified mitigation cannot offset an unquantified impact.
Analyze cumulative and connected water effects of what SAMP-driven cargo growth, the SR-509 corridor, and the North of NERA industrial buildout will do to the drinking water aquifer, the West Fork Miller Creek that runs through it, and the salmon waters of Miller Creek downstream.
Identify the permits (Industrial Stormwater General Permit, 401/shoreline, cleanup-site requirements) under which any deferred analysis will be completed.
3.12.1 The existing stormwater infrastructure is already documented as failing
The City's 2020 Storm Drainage Master Plan identifies areas of the Burien drainage system where "drainage and water quality can be improved,” a systemwide inventory of pipes, culverts, and ditches needing capacity or treatment upgrades. Right next door to North of NERA, downstream of the rezone area, the City is running the Boulevard Park Flood Reduction Project. The City's own project page describes "widespread chronic flooding" in that neighborhood, along with "annual significant flooding of several properties and structures, beyond what was experienced previously." The Valley View Sewer District SEPA package for the Boulevard Park sewer extension reproduces engineering findings that stormwater in this drainage "has been highly modified and piped, exacerbating flooding issues" and that at least one downstream conveyance pipe "is undersized and fails to effectively convey stormwater during the wet season." Two separate agencies agree on record: the drainage system is already overwhelmed.
Adding new impervious surface for cargo lots, parking, and warehousing replaces grass and trees with pavement. Pavement does not soak up rainwater, sending runoff into the drainage system. This is exactly the kind of cumulative impact SEPA requires the Port to analyze on the record. Under WAC 197-11-330(3)(c), "several marginal impacts when considered together may result in a significant adverse impact," and under WAC 197-11-060 that analysis belongs in the environmental document — not deferred to a future permit, leaving the City of Burien and Valley View Sewer District to reconstruct after the fact.
Quantify SAMP's cumulative flow contribution to the Burien drainage system, including the Boulevard Park basin the City has documented as experiencing "widespread chronic flooding," and quantify the added peak flow from the 74.43 acres of net new impervious surface by discharge point.
Identify each downstream conveyance receiving SAMP-driven flow, its rated capacity, and whether it is among the segments the City and Valley View Sewer District have already documented as undersized.
Disclose whether the Port has consulted the City of Burien and Valley View Sewer District on SAMP-driven flow, and identify any capacity commitments, cost-sharing arrangements, or interlocal agreements that exist or are contemplated.
Analyze flood risk to properties and structures downstream of the North of NERA area under both current and post-buildout conditions, using current precipitation and drought-cycle data rather than historic design storms.
3.12.2 6PPD-Q: the live regulatory framework the DEIS does not engage with
6PPD-quinone (6PPD-Q) is a chemical that forms when tire rubber reacts with ozone. When rain washes tire dust off pavement into a body of water, the 6PPD-Q that comes with it kills coho salmon at concentrations far below what the human eye can see. Miller Creek and Des Moines Creek — both directly affected by SAMP-driven runoff — are exactly the kind of urban salmon and trout streams the science is about, and the Port's own Miller Creek Restoration Project was built for the coho the criterion is designed to protect.
Since the DEIS was scoped, Washington's regulatory floor for 6PPD-quinone has changed. Ecology has adopted the nation's first numeric freshwater acute aquatic life criterion for 6PPD-Q under Chapter 173-201A WAC. The 2024 Stormwater Management Manual for Western Washington is now the governing rulebook for stormwater controls on new development. The 2025 Industrial Stormwater General Permit (ISGP) sets a facility-level 6PPD-Q benchmark of 15 ng/L (the concentration a facility's discharge is expected to stay below). And the 2024 Municipal Stormwater Permits apply the new manual to the cities discharging into the same waters. In other words, the regulatory system now treats 6PPD-Q as a pollutant that facilities and cities have to measure, manage, and reduce. A DEIS proposing 74.43 acres of new impervious surface draining to the Miller Creek does not name the chemical once.
The aquatic-life criterion is not the only reason the DEIS silence is inadequate. 6PPD-Q has now been detected in Washington tap water, with the highest estimated daily intake in infants (Ecology 6PPD Monthly Update, September 2024). EPA has opened an Advance Notice of Proposed Rulemaking on 6PPD under TSCA, expressly citing human inhalation, dermal, and ingestion exposure as reasons for federal action. No numeric human-health water quality criterion for 6PPD-Q has yet been adopted, but SEPA's disclosure duty does not require it to wait for one. The drought conditions described in §3.12 concentrate this chemical: lower summer base flow means less dilution during the season coho are returning. Where a chemical has documented human exposure, an adopted state aquatic-life criterion, and an open federal rulemaking track, a DEIS that treats it as absent from the analysis is inadequate.
Communities, tribes, and advocates are calling for additional mitigation efforts to further reduce 6PPD-q contamination, as soon as possible. In May 2026 Puget Soundkeeper called for a firm phase-out deadline and for tribal consultation and leadership to be "foundational, not supplemental" in the 6PPD response.
None of this appears in the DEIS. The DEIS discusses stormwater without naming 6PPD-Q, without identifying the 2024 aquatic life criterion, without naming the ISGP or the 2028 sampling start, and without identifying the Phase I / Phase II municipal permits governing the SAMP discharge points.
What the Final EIS must do:
Name the applicable stormwater regulatory framework under WAC 197-11-440(6): the 2024 6PPD-Q Water Quality Criterion in Chapter 173-201A WAC, the 2025 ISGP with its 15 ng/L benchmark and 2028 sampling start, the 2024 Phase I / Phase II Municipal Stormwater Permits, and the 2024 SWMMWW.
Identify that 6PPD-Q loading analysis for SAMP-driven traffic increases is being deferred to the ISGP permitting stage (WAC 197-11-060(5)), specify the timing, and commit to producing the loading estimates the ISGP permit application will require.
Disclose 6PPD-Q as a reasonably foreseeable human exposure pathway, even in the absence of a numeric human-health criterion, given documented Washington drinking water detections and EPA's open TSCA rulemaking.
Analyze the interaction between SAMP construction and operational stormwater discharge and the 2025 Industrial Stormwater General Permit including how the January 1, 2028 6PPD-Q sampling requirement for air transportation facilities will apply to SAMP-affected discharge points.
Analyze the feasibility, cost, and pollutant-removal performance of construction-phase and operational 6PPD-Q controls the Port could implement now including enhanced street sweeping during high-traffic construction periods with catch-basin decant waste treated through the Pierce County settling and granular activated carbon process, and retrofit of existing SDS bioretention facilities discharging to Miller Creek and Des Moines Creek with high-performance bioretention soil media, a technology the Port already deploys on the marine side.
3.12.3 Wetlands
The DEIS describes SAMP as a 31-project package — second terminal, ground transportation center, off-site cargo facilities, fuel-farm expansion, taxiway extensions, and the North of NERA rezone. The Port property today holds 132 acres of wetlands. The Port's own 2007 Comprehensive Development Plan EA identified 111 acres on the same footprint. The DEIS asks readers to believe this 31-project buildout will permanently affect less than 1 acre of wetlands, less than 3 acres of wetland buffers, 0.01 acre of streams, and 0.12 acre of stream buffers (DEIS Summary). That is not credible.
Part of how that number stays small is what it leaves out. The DEIS reports permanent impacts. It does not report the temporary ones like the construction phase disturbance to salmon bearing streams, seasonal wetlands, and buffer vegetation that occurs while a project is being built. A footprint that looks small on the final drawing can involve years of in-water and near-water work, and none of that appears in the acreage the DEIS puts in front of the reader.
The DEIS does not identify where compensatory wetlands would be located. If mitigation is placed outside the Miller Creek, Des Moines Creek, or Gilliam Creek basins, (“off-basin”) the project may replace acreage on paper while exporting mitigation away (possibly to Auburn) so nothing is done to help the actual watersheds that lose flood storage, summer shading, aquifer recharge, and salmon habitat.
Which agency actually reviews these impacts, and under which permit, matters a LOT more than it sounds.
The Final EIS must:
Reconcile the claimed impact acreage with the Port's wetland inventories. Explain how a 31-project buildout across a footprint the Port documented at 111 acres of wetlands in 2007 and 132 acres today produces less than 1 acre of permanent wetland impact, and disclose the delineation methodology, delineation date, wetland type, and rating category under Ecology's Wetland Rating System for every wetland and stream on the SAMP footprint.
Disclose the temporary wetland and stream impacts from construction, not just the permanent ones, including duration, in-water work windows, and effects on salmon bearing reaches, seasonal wetlands, and buffer vegetation.
Publish the replacement ratio for every lost wetland and stream acre and the specific location where that replacement will occur for each project. Vague promises of "future mitigation" are not analysis.
For each proposed off-site or out-of-basin mitigation action, document under 33 CFR 332.3(b) why in-basin mitigation is not practicable, using the required watershed-approach analysis.
Analyze the effect of the proposed mitigation pathway on treaty-reserved resources of the Muckleshoot Indian Tribe under the 1855 Treaty of Point Elliott including salmon habitat in Miller Creek, Des Moines Creek, and the Green/Duwamish, and of the Suquamish Tribe, whose treaty-reserved marine and shellfish resources are affected by SEA-related stormwater discharge and atmospheric deposition. Both Tribes hold government-to-government MOAs with the Port.
Analyze the environmental justice consequences of exporting wetland function out of Burien, SeaTac, Tukwila, Des Moines, the Duwamish Valley, and unincorporated south King County, communities the DEIS itself identifies as already carrying cumulative environmental burden.
Confirm on the record that the Miller Creek Restoration is not being counted as compensatory mitigation for SAMP impacts.
3.12.4 The DEIS does not say which permitting path SAMP will use and that determines whether Washington reviews these projects at all
Think of it like a restaurant kitchen. You can inspect it project-by-project every time something changes, or you can hand the restaurant a single blanket approval that covers the whole operation for years. Both are "permits." Only one of them actually looks at what is happening on any given day. The DEIS does not say which path the Port intends to use.
Path 1: The Port runs its projects through the U.S. Army Corps of Engineers, using a preferred federal permitting track via the Water Resources Development Act. Under that path, Washington's water quality sign-off is handled in bulk by the Corps, not Ecology; and it grants a single blanket approval that covers many projects at once, with no state review of any individual SAMP project.
Path 2: Each SAMP project gets its own state water quality review from the Washington Department of Ecology (individual Section 401 Water Quality Certification). Ecology looks at that specific project's specific impacts, on the specific streams downstream from it, before issuing the permit.
Here is what makes this choice urgent. In 2023, the U.S. Supreme Court (Sackett v. EPA) narrowed the definition of which waters count as federally protected. Many of the wetlands and streams around SEA may no longer be federally protected at all. When federal protection shrinks, state protection is what is left and Ecology's independent authority over state waters under Chapter 90.48 RCW becomes the only backstop.
So. The permitting path is not a paperwork question. It is the difference between Ecology taking a real look at every SAMP project's impact on Miller Creek, Des Moines Creek, Gilliam Creek, the Green/Duwamish, or Ecology certifying a SEPA record that never analyzed those impacts at all.
Ecology completed its water quality review of the permit categories SAMP would use on December 18, 2025, five months before this DEIS was published. Ecology provided public notice of that review on July 25, 2025, and states plainly: “No comments were received.” Ecology further acknowledged that it was certifying against draft regional conditions and that “it is likely that there will be changes in the final regional conditions” — changes the Corps did not publish until March 10, 2026 (Seattle District final regional conditions). The permits took effect March 15, 2026 (91 FR 768).
If the Port intends to authorize SAMP projects under NWP 14, 39, 42, 43, 7, or 33 and rely on that programmatic certification, then the State of Washington will never have conducted a project-specific water quality review of this program. This comment period is the last opportunity anyone will have to raise SAMP’s water quality impacts with Ecology.
What the Final EIS must do:
The Final EIS must state, for each of the 31 SAMP projects, which Section 404 authorization the Port intends to use — nationwide permit (specify which), individual permit, or none —and whether the Port will rely on the programmatic Section 401 certification or seek individual certification. Identify the Corps district and the Section 401 certifying authority for each project.
Disclose any coordination arrangement between the Port and the Corps that affects the SAMP permitting timeline, scope, or review process, including any arrangement under the Water Resources Development Act.
Analyze which wetlands and waters on the SAMP footprint remain jurisdictional after Sackett and which do not, and identify how Ecology's independent state authority under Chapter 90.48 RCW applies to the non-jurisdictional waters.
Analyze whether the SAMP permitting timeline permits Ecology's independent SEPA review to occur before federal permitting decisions are made, or whether those decisions will pre-empt state analysis.
3.13 The Port already contaminated one drinking-water well with PFAS. The DEIS proposes building on top of another to store SAFs, a fuel chemistry it has not analyzed.
PFAS ("forever chemicals") are toxic at concentrations far below what a lab can easily see, and they do not break down in the environment. The airport has already contaminated one Highline drinking-water well (Tyee in 2022) and the Port paid Highline Water District a damages settlement in September 2024 to resolve that harm. The DEIS now proposes construction inside the protection area of another Highline well (McMicken) and expansion of the fuel farm atop the same aquifer using the same categories of safeguards that failed before.
Because PFAS does not break down, contamination is persistent and extremely costly to remove, and it threatens not only the soil at each identified site but every water body that stormwater carries it into; it is critical that the airport take proactive measures to adequately protect the natural environment and the community from PFAS contamination.
The airport has already identified areas of concern for PFAS contamination and identified 16 locations where firefighting foam had been deployed and contaminated areas on airport property (3-54). According to the draft EIS, there are:
“Five sites where PFAS is either stored or has been deployed for an incident would be impacted by the Action Alternatives. These include H-60 (testing / training location), H-63 (engine fire on Taxiway B), H-67 (ARFF Station), H-72 (Fuel Farm release), and H-73 (Fuel Farm storage). Construction occurring on or near these sites would follow Port specifications for handling contaminated soil noted above. As regulations for PFAS are in development at the state and federal level, the Port would ensure work is conducted in accordance with all applicable PFAS regulations in place at the time of construction.” (4-46)
At §4.3.14.5, the DEIS states that the Action Alternatives would cause "a permanent impact of 2.24 acres to the wellhead protection area associated with the McMicken Heights well east of the Airport" due to a utility line connection (DEIS §4.3.14.5, lines 5665-5667). That is the entire analysis. The DEIS does not analyze whether utility line construction inside a wellhead protection area could remobilize existing contamination toward the McMicken Well. It does not disclose current McMicken water quality monitoring data. It does not analyze whether construction dewatering could draw contaminated groundwater toward McMicken. It does not consider what would happen to Highline's supply capacity if McMicken had to be voluntarily suspended like Tyee. It does not indicate whether Highline was consulted about the wellhead protection area disturbance.
Before 2022, the Port followed a set of standard rules meant to keep pollution out of groundwater: best management practices for handling fuel and firefighting foam, spill prevention regulations, engineered containment for storage tanks, and construction standards for anything built on airport property. Those safeguards were in place the whole time PFAS was moving through the aquifer to Tyee. They failed.
The DEIS now proposes to install a utility line inside the wellhead protection area for the McMicken Well — one of only three Highline wells still in service after Tyee — using the same categories of safeguards.
The Fuel Farm Expansion (Project S01) compounds the risk. The Chapter 1 – Purpose and Need states the project will add four new settling tanks (~10 million gallons storage capacity), a ~500,000-gallon blending tank, a ~100,000-gallon Sustainable Aviation Fuel (SAF) receipt tank, additional piping, an expanded spill containment dike, and a new truck fuel rack to support SAF blending, targeting 22–31 million gallons of fuel reserve for 7–10 days of supply.
SAF has a different chemical makeup than conventional Jet A, with different content and different breakdown products in soil and water. The Ecology 2008 groundwater study the Port relies on predates commercial SAF entirely. The DEIS does not analyze what expanded storage of an unstudied fuel chemistry over a documented contaminated aquifer means for groundwater, and does not identify whether existing groundwater monitoring is capable of detecting SAF-specific breakdown products.
What the Final EIS must do:
Name the applicable regulatory framework and disclose what is being deferred. Under WAC 197-11-440(6), identify Chapter 173-340 WAC (MTCA) and the currently applicable PFAS SIPP (Source Identification and Prioritization Program) values as the governing standards. Under WAC 197-11-060(5), state on the record that PFAS characterization is being deferred to the Section 401 Water Quality Certification, and identify the timing.
Explain, with evidence and analysis, what has changed since the Tyee shutdown that would prevent a repeat, and what happens to Highline's water supply if the answer turns out to be "not enough."
Disclose current monitoring data for McMicken, Angle Lake, and Des Moines wells, and analyze whether construction dewatering, utility-line trenching, or expanded fuel storage could remobilize existing groundwater contamination toward those wells.
Analyze SAF as its own chemistry. Identify the SAF feedstock and pathway the Port is planning for SEA, the breakdown products expected in soil and groundwater, and whether existing groundwater monitoring at the Fuel Farm is capable of detecting them. State whether the 2008 Ecology groundwater study — which predates commercial SAF entirely — remains a defensible basis for characterizing baseline conditions under the Action Alternatives.
Acknowledge that the regulatory framework the Port's mitigation strategy relies on — EPA's PFAS drinking-water rule, Ecology's SIPP values — is in active development and under legal challenge, and identify what the contingency is if any framework(s) are weakened before construction is complete.
3.14 Future permitting cannot substitute for SEPA analysis (including SAFs)
The DEIS points to future permits as the place where impacts will be addressed. Permits matter, but the presence of a permit does not automatically address PFAS contamination, 6PPD-Q, or polluted stormwater runoff. Permits are not the SEPA document. The SEPA record is where the public gets to comment, where the analysis has to be in the record, and where the Port has to disclose what it is deferring and to whom.
Under WAC 197-11-660(1)(b), mitigation must be tied to specific, adverse environmental impacts identified in an environmental document on the proposal. When the SEPA record does not disclose an impact, the SEPA based mitigation track for that impact is closed off: no future permit condition tied to that impact can rest on the SEPA record, because the SEPA record never analyzed it. Permitting agencies retain their independent statutory authority but the SEPA layer of protection cannot be recovered later. Also, under WAC 197-11-060(5), when a lead agency uses phased review to defer analysis to future permit processes, it must identify what has been deferred, to which permit, and why. The Final EIS cannot meaningfully respond to comments never made on a framework the DEIS never names.
SAF is the clearest example of the Port deferring analysis to a framework that does not exist yet. Sustainable Aviation Fuel (which Ecology now calls "alternative jet fuel" or AJF) is central to the Port's description of SAMP. SEA has committed to at least 10% SAF for every flight fueled at the airport by 2028. The Fuel Farm Expansion (Project S01) commits airport infrastructure now (~500,000-gallon blending tank, ~100,000-gallon SAF receipt tank, a new SAF truck fuel rack) to a fuel chemistry for which the environmental review is still being written.
Ecology is currently preparing a Programmatic Environmental Impact Statement (PEIS) on Alternative Jet Fuel Production, Blending, and Storage Facilities in Washington State. Scoping closed in November 2025. The Draft PEIS is planned for public comment in early 2027. The Final PEIS is planned for June 30, 2027, which is after the SAMP DEIS comment period closes and likely after the SAMP Final EIS is issued. The Port's SEPA process on SAF supporting infrastructure will close before Ecology's SEPA process on SAF itself is even in draft form.
The DEIS is also silent on which supply model SEA is planning. Ecology's scoping summary notes that the National Renewable Energy Laboratory "found that airports are unlikely to own or operate their own blending facilities" and that blending is "likely to be located upstream of airports either at the production facility, a standalone blending facility, or at an existing refinery." The DEIS describes a blending tank and a SAF receipt tank without clarifying whether SAF will be blended on-airport or delivered pre-blended, and does not identify which fuel pathway or feedstock will supply the airport. Each model produces a different environmental risk profile—groundwater, air, spill risk, fire risk—and the DEIS does not tell the community which one it is.
Ecology's PEIS is also explicit that it will not resolve site-specific issues: "A PEIS does not approve or deny a proposed project" and "such effects must be evaluated at the project level." Ecology's PEIS identifies "Water resources" and "Environmental health and safety" as elements that require project level review. The Port cannot use Ecology's in-progress PEIS as a substitute for its own analysis of what expanded SAF blending and storage on top of the Qva aquifer will mean for water, air, and environmental health and safety in South King County. (For the aquifer chemistry problem specifically — SAF's different chemical makeup, the outdated 2008 Ecology study, and existing monitoring's inability to detect SAF-specific breakdown products, see §3.13.)
What the Final EIS must do:
Under WAC 197-11-060(5), identify each analysis the Port is deferring, the specific permit vehicle it is deferring to, the responsible agency, and the expected timing. Under WAC 197-11-440(6), it must name the specific regulatory frameworks that will govern the deferred analyses.
For SAF specifically, the Final EIS must state on the record which SAF supply and blending model the Port is planning for SEA (on-airport blending, delivery of pre-blended SAF, or other configuration), identify the SAF pathway and feedstock, and analyze the site-specific water, air, spill, and fire risk profile of that model. Under WAC 197-11-660(1)(b), SEPA mitigation must be tied to impacts identified in the SEPA record; a DEIS that does not disclose the model, the pathway, or the risk profile cannot support SEPA-based mitigation for any of them.
If the Port is relying on Ecology's in-progress Programmatic EIS on Alternative Jet Fuel Production, Blending, and Storage Facilities (Draft in early 2027, Final by June 30, 2027), commit on the record to project-level re-review of the SAMP Fuel Farm Expansion (Project S01) against Ecology's Final PEIS when it is issued, including any additional SEPA analysis needed to satisfy Ecology's PEIS finding that "such effects must be evaluated at the project level."
Establish enforceable, project-level monitoring and testing requirements for PFAS, 6PPD-quinone, and heavy metals in stormwater runoff, including sampling locations, frequency, laboratory methods, action levels, and a public data platform for publishing results, that are tied to specific SAMP projects and disclosed in the SEPA record rather than deferred to future permit conditions.
3.15 Appendix O (Agency Engagement) is blank
Appendix O is empty. SEPA is a public-process statute. Appendix O is where the record of who the Port talked to is supposed to live. There is no record of engagement with any Tribe on cultural, treaty, or environmental interests; no record of engagement with Ecology, Public Health – Seattle & King County, Puget Sound Clean Air Agency, or WSDOT on cumulative burdens; no record of engagement with the impacted cities on land use and infrastructure interactions. This omission alone is grounds to withdraw and reissue the DEIS.
The federal record confirms Appendix O’s silence hides a real gap. NEPA EA Appendix G lists ten Tribes as “contacted” for Section 106 consultation, but documents only one formal FAA initiation letter, dated July 28, 2021, to Chairman Delano Saluskin of the Confederated Tribes and Bands of the Yakama and forwarded emails to the Warm Springs, Snoqualmie, and Suquamish Tribes on July 29, 2021. Six of the ten named Tribes have no documented FAA outreach in the appendix that is supposed to memorialize it: the Muckleshoot Indian Tribe, the Puyallup Tribe of Indians, the Samish Indian Nation, the Squaxin Island Tribe, the Stillaguamish Tribe of Indians of Washington, and the Tulalip Tribes of Washington.
Three Tribes responded. The Confederated Tribes of the Warm Springs Reservation submitted technical comments through its Tribal Historic Preservation Office, expressly stating: “Please know that review by the Tribal Historic Preservation Office does not constitute Government-to-Government consultation. Please ensure that appropriate Government-to-Government consultation is made with the Confederated Tribes of the Warm Springs Tribal Council.” The Snoqualmie Indian Tribe offered “no substantive comments to offer at this time.” The Suquamish Tribe reported no historical or ethnographic information on the specific project areas and asked to receive the cultural resource assessment. None of these is a substantive tribal consultation record on the SAMP proposal, and one is a Tribe directing the FAA that the required government-to-government consultation has not been conducted.
The Muckleshoot Indian Tribe — the federally recognized successor in interest to the 1855 Treaty of Point Elliott signatories whose treaty territory encompasses the land SEA occupies — is not just absent from the response record. It is absent from the outreach record. The FAA cannot document consultation it did not conduct, and the Port cannot inherit a consultation record that does not exist.
Tribal consultation is a separate legal obligation from public engagement, and Section 106 is a federal historic-preservation process focused on effects to historic properties. The Port cannot use the Section 106 record to meet its own consultation duty under SEPA on cumulative health disparities, treaty fishing and shellfish rights, or PFAS loading to treaty resources.
Washington also has its own rules. Governor's Executive Order 21-02 requires state agencies to consult Tribes directly on cultural-resource impacts, and the Centennial Accord (1989) and Millennium Agreement (1999) establish that this consultation happens government-to-government, not through federal middlemen.
The Port has the frameworks. It has not shown it used them. In 2023, the Port signed a government to government MOA with the Muckleshoot Indian Tribe, followed by a parallel MOA with the Suquamish Tribe in January 2025. Both MOAs establish structured consultation frameworks. The SEPA DEIS does not show whether either was used to re-engage those Tribes on SAMP. The Port must produce, for the record, every communication it has had with the Muckleshoot Indian Tribe and the Suquamish Tribe on the SAMP proposal under the 2023 and 2025 MOAs or acknowledge that none exists.
Instead, the Port hangs the state consultation duty on the federal record. The DEIS states that “This SEPA EIS incorporates by reference Section 3.3.8 (Historic, Architectural, Archaeological, and Cultural Resources) of the NEPA EA” and “adopts by reference the Area of Potential Effects (APE) identified by the FAA that received [DAHP] concurrence.” Chapter 1 §1.4 lists the FAA’s Section 106 determination and DAHP’s concurrence on that determination as the only cultural-resource approvals for SAMP — both federal-track, neither a Port-led state consultation with any Tribe. The Summary (p. S-16) describes the Draft EIS itself as having been “released for public, agency, and tribal review on May 22, 2026,” as though publishing satisfies a consultation duty. Publication of the DEIS is public notice. It is not consultation, and it is not tribal engagement.
Beyond the process failure, Appendix O's silence conceals the substantive content that tribal consultation should have generated. A consultation record for a project of this scale and location should have addressed:
Water, salmon, and drinking water
Impacts on treaty-reserved fishing rights in the Green/Duwamish, Miller Creek, Des Moines Creek, and Gilliam Creek watersheds, including PFAS loading to salmon and shellfish, tribal subsistence consumption rates that differ from state-average rates, and the effect of dropping Gilliam Creek, the airport’s hydrologic connection to the Lower Green River, from the DEIS’s affected environment in a footnote (Chapter 3, p. 3-109, fn. 36).
Impacts on treaty-reserved shellfish rights in Puget Sound nearshore areas from stormwater and air deposition, including impacts to the Suquamish Tribe’s treaty-reserved marine resources under the 1855 Treaty of Point Elliott.
Impacts on drinking-water supplies serving tribal members and tribal households in the Highline Water District service area, including the McMicken Well wellhead protection area disturbance and the Fuel Farm Expansion (Project S01) over the Qva aquifer that already carried PFAS to the Tyee well.
Land, plants, and cultural resources
Impacts on treaty-reserved hunting and gathering rights on lands within the affected area, including effects on culturally significant plants from air quality changes and habitat conversion.
Identification of Traditional Cultural Properties, sacred sites, and burial sites through consultation with the Muckleshoot Indian Tribe and analysis of project effects on those resources.
Sacred viewshed and cultural soundscape analysis, including effects on ceremonial use of the airport-adjacent landscape.
Cross-cutting
Climate change impacts on treaty-protected species and habitats and SAMP’s cumulative contribution.
Coordination between the HEAL Act analysis and Section 106 / NEPA tribal consultation, which currently proceed on separate tracks with no documented integration.
None of these appears in the DEIS. The remedy is not a cross-reference to a future document; it is to develop the analysis, with tribal participation and approval, and reissue the DEIS.
3.16 Mitigation is vague, deferred, and not enforceable
Look for the word "if" in the DEIS mitigation language and you will understand the problem. The Port commits to engaging affected communities and considering mitigation only "if necessary" with no definition of what makes something necessary, no deadline, and no one responsible for making sure it happens.
Appendix K commits the Port to "conduct meaningful engagement of the affected EJ populations to provide information on the impact analysis and context-specific mitigation measures and actions, if necessary." There is no definition of "if necessary," the timeline, no accountability mechanism, and no binding commitment. Vague commitments to "consider" future measures fail SEPA's standard. Under WAC 197-11-660(1)(b), mitigation must be tied to impacts clearly identified in an environmental document on the proposal.
The final EIS must identify concrete, enforceable, funded mitigation for each significant impact–mapped to the neighborhoods where the impact lands—with specific timelines, responsible parties, funding sources, performance standards, public reporting, independent monitoring, and consequences if the Port or partners do not meet those standards. Downstream permitting agencies have their own independent statutory authority, but SEPA requires the lead agency itself to produce an adequate analytical record and to attach mitigation to specific disclosed impacts. Deferring substantive analysis to later permit proceedings, which involve narrower scopes, different agencies, and different (or no) public-comment rights, denies both the reviewing agencies and the public a meaningful chance to weigh the project's environmental impacts at the point when SEPA requires that consideration.
4. What residents want. What SAMP delivers.
Residents across airport-impacted cities have said clearly what kind of city they want. SAMP delivers something different. This table shows the mismatch at a glance so SEPA reviewers can see where the DEIS fails where the law requires it to analyze.
| What residents want | What SAMP delivers | What SEPA asks the Port to study |
|---|---|---|
| Keep our trees and trails | 56.4 acres of trees cut down for cargo lots and roads; young saplings replacing trees that took 30 to 50 years to grow | Combined tree loss with SR-509 and warehouse projects, heat island impacts (see §3.6, §3.7) |
| Density balanced with livability; A healthy place to raise a family | More flights, diesel trucks, and ground equipment in ZIP codes already among the worst for health in King County | Cumulative UFP+ PM2.5+noise; a children's health analysis using UW and EHD data (see §3.3, §3.4) |
| Affordable housing | A rezone next to SR-509 that raises land values in historically affordable POCIR neighborhoods | Displacement; SEPA “built environment analysis of homes, cultural spaces & small businesses (see §3.9) |
| Safe streets to walk or bike, with more buses | Trucks routed onto the same streets residents already said were unsafe | Pedestrian and bike safety; cumulative freight impact; who pays for road repairs; off residential freight alternatives (see §3.8) |
| Local shops and small businesses that reflect the community | Industrial rezoning displaces neighborhood retail; Port contracts flow to large firms | Small-business displacement analysis; zip code level contract/jobs breakdown; enforceable local contracting mitigation (see §3.9, 3.10) |
| Equity, community voice, diversity; A real say in decisions that affect us | The Port is both the applicant proposing this project and the agency that approves it; comments haven’t changed designs; low English Proficiency communities only get summarized translations, and only if they ask | An honest environmental-justice review, community research included in the baseline, and real advisory panels with power, not just listening sessions (see §3.11, §3.16) |
| Stormwater. Clean creeks and healthy watersheds | New impervious surfaces plus fuel, industrial, and deicing runoff stress Miller Creek, Des Moines Creek, and the downstream wetlands; no plan to consider permeable pavement or elevated 6PPD-Q mitigation during construction | Cumulative stormwater across SAMP + SR‑509 + warehouses on the same watersheds; downstream impact in Burien and Des Moines, plus green infrastructure mitigation to protect Burien and Des Moines waterways (see §3.12) |
5. What residents live with vs. what is missing from the DEIS
| What residents live with | What the DEIS says about it | What the DEIS leaves out |
|---|---|---|
| The North of NERA / Cedarhurst rezone is bringing more warehouses and trucks into a residential neighborhood right next to the new cargo expansion | Not studied — the Port calls zoning a city decision and says North of NERA is outside SAMP's scope | Whether airport growth is driving the rezone and what that means for traffic, noise, pollution, displacement. The Burien comp plan was created in partnership with the Port. |
| SAMP promises hundreds of new jobs but can people who live nearby actually get them | Counts jobs across the whole state, not locally | A ZIP-code, race, and equity breakdown of who actually benefits, and the language, credential, transportation, and access barriers that stand in the way |
| Warehouse boom across South King County, nearly a million square feet at the former Wild Waves site alone, sending freight through our streets | Not mentioned. Warehouse growth off Port property is treated as background noise | How much extra truck traffic and diesel exposure residents in SeaTac, Burien, Des Moines, and Tukwila should actually expect |
| The SR-509 extension will carry more freight, more air and pollution, and trucks through neighborhoods already atop the state's health-burden scale | Mentioned briefly as a "separate project" | How SR-509, SAMP cargo, and warehouse growth together change traffic, noise, and air pollution in the same neighborhoods, and what added mitigation is needed |
| Our neighborhoods already score 9 or 10 out of 10 on Washington's health disparities map — the worst possible score | Confirms many tracts around the airport are environmental-justice communities with very high disparity scores and very low Port equity scores | Whether + 31 new projects and related traffic to the highest-burden tracts in the state can honestly be called "not significant," and what extra protection the law requires |
| Kids and families dealing with asthma, heart disease, sleep loss, and stress near the airport, highways, and warehouses | Acknowledges high vulnerability and existing health risk, but concludes the project is not "significant" because modeled pollution and noise stay under federal thresholds | A study focused on children, elders, low-income households, immigrants, renters, and outdoor workers and the extra protection schools & parks need. |
| Everything is happening at once: airport growth, cargo, SR-509, warehouses, construction, noise, air pollution, and climate risk, stacked in the same neighborhoods | Reviews each category on its own; concludes nothing is "significant" once mitigation is factored in | Whether the DEIS actually accounts for the combined weight of all of this on communities already overburdened, instead of slicing it into separate small pieces |
| Promises, pilot programs, and vague equity language | Frames mitigation and equity commitments as ideas or programs, not binding conditions | Enforceable mitigation: deadlines, responsible parties, funding, public reporting, measurable standards, independent monitoring, & sanctions for missed commitments. |
Conclusion
The airport is proposing to grow. The neighborhoods around it are already carrying more than their share of airport impacts — more asthma, more heart disease, more diabetes, more traffic, more noise, shorter lives. This is not our claim. It is the Port's–and the State’s–public health record.
The DEIS does not honestly reckon with any of that. It draws its analysis close to the airport property line as if the pollution stops there. It measures air quality against a federal ceiling that Ecology has already proposed to tighten by roughly 3–4× for the permits SAMP will need. It leaves out ultrafine particles, one of the pollutants most closely tied to airport-adjacent disease. It relies on a 1.5 dB noise significance test that was built for federal aviation convenience decades ago, long before the health science on transportation noise, cardiovascular disease, and cognitive decline was in. It treats the warehouses, the freeway extension, and the rezones that SAMP is driving as somebody else's problem — even though the Port itself, in a June 24, 2026 filing before the Seattle Hearing Examiner (File W-26-001), just told a different tribunal that mixing residential uses with "active industrial and freight corridors" causes real, non-hypothetical conflicts due to “truck traffic, rail and port operations, nighttime activity, noise, emissions, safety.” It is silent on Washington's 2024 6PPD-quinone Water Quality Criterion and the 2025 Industrial Stormwater General Permit — the standards that will actually govern the stormwater flowing into salmon-bearing streams and an aquifer multiple cities depend on. It defers to permits it has not yet applied for, without disclosing under WAC 197-11-060(5) which analyses are being deferred, to which permit, and on what timeline. And where the record of consultation with Tribes, agencies, and cities is supposed to live — Appendix O — the Port left the page blank. Not sparse. Blank. That silence sits on top of a 2021 federal Section 106 record that documents outreach to only four of ten named Tribes and no letter of any kind to the Muckleshoot Indian Tribe, whose treaty territory encompasses the land SEA occupies. Publication of a Draft EIS is not consultation. It is not tribal engagement.
A community already scoring 9 or 10 on the state's Environmental Health Disparities map does not need another environmental document that concludes "no disproportionate and adverse effects." It needs an honest one.
We are asking the Port to withdraw and revise the Draft EIS, or issue a Supplemental Draft EIS, before moving to a Final EIS. What the Final EIS must do:
Study the flight-funnel and freight-corridor communities that live with the impacts, not the fenceline. with per-city cumulative-impact tables for Burien, Des Moines, SeaTac, Tukwila, Federal Way, the Duwamish Valley, and unincorporated King County, and using the state’s Environmental Health Disparities map and the HEAL Act overburdened-community framework as inputs to the significance determination, not demographic background.
Add a full ultrafine-particle analysis using UW MOV-UP data, Puget Sound Clean Air Agency and Ecology monitoring, and community-generated data, and replace the 1.5 dB noise significance test with a population-exposure analysis based on current WHO and EPA health thresholds.
Reconcile projected greenhouse-gas emissions against RCW 70A.45 and the Climate Commitment Act trajectory, and disclose any shortfall in the significance determination itself, not just in an appendix table.
Quantify 6PPD-quinone, PFAS, copper, and zinc loading to Miller Creek, Des Moines Creek, Gilliam Creek, and the Green/Duwamish, and evaluate effects on coho salmon, cutthroat trout, and any other ESA-listed fish documented in the affected receiving waters.
Name the permitting pathway and every deferred analysis. State which Section 404 authorization the Port will use for each of the 31 SAMP projects — nationwide (specify which), individual, letter of permission, or none — and whether the Port will rely on Ecology’s December 18, 2025 programmatic Section 401 certification or seek individual certification. Under WAC 197-11-060(5) and WAC 197-11-440(6), identify each deferred analysis, the responsible permit and agency, the timing, and the governing framework — including the 2024 6PPD-quinone Water Quality Criterion, the 2025 Industrial Stormwater General Permit, Chapter 173-340 WAC (MTCA), the currently applicable PFAS SIPP values, the HEAL Act, Ecology’s air-pollution rulemaking, and the 2024 Stormwater Management Manual for Western Washington.
Complete government-to-government tribal consultation and fill Appendix O. Engage the Muckleshoot Indian Tribe and the Suquamish Tribe through the Port’s existing MOAs and any other Tribes with treaty-reserved resources in the affected watersheds under Executive Order 21-02, the Centennial Accord, and the Millennium Agreement. Analyze impacts to treaty-reserved fishing, hunting, gathering, and shellfish-harvesting resources. Reissue the Draft EIS if consultation materially changes the analysis.
Attach concrete, funded, enforceable mitigation to each disclosed impact in the neighborhoods carrying the burden — canopy replacement in the same census tracts, pedestrian and freight-routing safety on Ambaum Boulevard and Des Moines Memorial Drive (including the eight unmitigated WSDOT-controlled intersections and pedestrian and bike safety, not just vehicle delay), cumulative watershed stormwater mitigation on Miller Creek and Des Moines Creek, and disclosure and analysis under WAC 197-11-444 of housing and population impacts, including displacement risk, where SAMP-driven industrial growth is projected to reshape residential neighborhoods.
SEPA gives the Port the authority and the duty to do this.
Burien, SeaTac, Tukwila, Des Moines, Normandy Park, Kent, Federal Way, Cedarhurst, the Duwamish Valley, Beacon Hill, Georgetown, South Park, and unincorporated south King County are not backdrop to this project. They are the environment SEPA requires the Port to evaluate. We will continue to be part of this record — in writing, in testimony, and in every permit process that follows — until the analysis matches the neighborhoods it affects.
Respectfully submitted,
SeaTac Airports Community Coalition for Justice (STACC4J)
350 Aviation
Creating Pathways
Duwamish River Community Coalition
King County International Airport Community Coalition
Puget Soundkeeper
Sustainable Seattle