Des Moines officials prepare for Sea‑Tac Sustainable Airport Master Plan; council backs continued ILA and multi‑level advocacy

Des Moines City Council Committee of the Whole members on Sept. 4 were briefed on the Sea‑Tac Sustainable Airport Master Plan (SAMP) process and directed staff to continue the four‑city interlocal agreement (ILA), pursue mitigation at the state and federal levels, and return to the council before advancing legal representation or airport‑committee presentations.

Rebecca Deming, Des Moines community development director, told the committee the Federal Aviation Administration published a draft NEPA environmental assessment on Oct. 21, 2024, and the public comment period closed Dec. 13, 2024. “We have been waiting for the responses to comments and final determination and release of their final EIA,” Deming said, adding that the Port of Seattle has indicated it will proceed with a SEPA environmental impact statement and is estimating a draft EIS release in 2026 with a 30‑day notice to the cities.

The city participates in a four‑city partnership formed by an ILA first executed in 2018; Deming said the partnership approved a new ILA in 2025 that runs through the completion of SAMP. The cities are meeting weekly and are exploring retaining outside counsel with NEPA and FAA expertise to support strategy, legal review and protection of city interests. Once a firm or team is identified, staff said it will brief council with more detail and likely discuss options in executive session because of sensitivity around strategy and costs.

Council members pressed staff about strategy and sequencing. Councilmember Harris, citing a prior 1996 study used during the third‑runway debate, urged updated, original research to identify long‑term economic and socioeconomic impacts so the cities can seek specific mitigation or compensation. “You have to have specific research that says it’s doing this to us,” Harris said, urging the council to consider asking the state to fund analogous updated work.

Anthony (legislative staff) flagged the legislative landscape: “there will be very, very little, in the way of legislation that will actually be passed by Congress,” he said, but added that federal advocacy and congressional relationships could still be used to pressure the FAA and to support the cities’ priorities. Council members generally supported a tiered approach of local committee work, council‑level engagement and legislative advocacy, and asked staff to return to council before presenting legal‑representation recommendations to the airport committee.

What the council asked staff to do: continue participation in the four‑city ILA, explore retaining counsel with FAA/NEPA expertise, pursue mitigation avenues at the state and federal level, and brief the full council (and, when appropriate, in executive session) before committing Des Moines to specific legal or litigation steps. Staff said it would present options and milestones, including cost estimates and partner positions, once proposals are gathered.

Background and next steps: the FAA’s NEPA process will determine whether a final environmental assessment or a full EIS is required; the Port of Seattle has signaled it will prepare an EIS under SEPA. The city manager and staff will continue coordinating with the four‑city partners, and staff indicated a possible federal “fly‑in” for joint advocacy could take place in April, with additional legislative work ahead of the January session.

No formal motions or votes were taken on the floor during the Committee of the Whole; the committee’s discussion produced direction to staff rather than a binding council action.