Committee forwards consent decree and settlement agreements for Lower Duwamish Superfund cleanup; county share estimated in the tens of millions

At the March 18, 2025 Transportation, Economy and Environment Committee meeting, Council Central staff and executive branch representatives presented proposed ordinance 2025‑0084, which would authorize the King County Executive to enter into a consent decree with the U.S. Environmental Protection Agency (EPA) and the Washington State Department of Ecology and to sign related multi‑party settlements to fund the cleanup of the Lower Duwamish Waterway Superfund site.

Andy Miklow of Council Central staff summarized the site and settlement background: the 5‑mile Lower Duwamish Waterway runs from the southern tip of Harbor Island to Tukwila and was contaminated by a century of industrial and commercial activity. The county’s potential liability relates to discharges from regional sewer infrastructure, King County International Airport property, Harbor Bond facilities and stormwater from county roads. The county joined the Lower Duwamish Waterway Group (LUDWIG) with the Port of Seattle, the City of Seattle and Boeing; a neutral allocation process assigned percentage cost shares in which King County received an 8.4 percent allocation overall, with a large portion of the county allocation assigned to the Wastewater Treatment Division (WTD).

Miklow and executive staff described the consent‑decree and settlement structure: performing parties (Boeing, the City of Seattle and King County) would implement the cleanup under EPA/Ecology oversight, other settling participants would pay cash‑out or funding shares, and the consent decree would set the cleanup timetable, require long‑term monitoring and controls (staff noted monitoring and controls could last decades) and settle liability subject to standard reservations and reopeners. Cleanup construction began under an EPA bridge order in November 2024; the consent decree would supersede that order once it is effective after lodging in federal court and a public comment period.

Miklow reported a 2022 cost estimate for the overall cleanup (a feasibility‑level estimate updated for inflation to 2022) of roughly $608.7 million. Using the allocation process, the county’s total share was estimated at approximately $59 million; executive staff said collateral funds and insurance recoveries will cover much of the county’s obligation. WTD’s remaining share after available funds is currently estimated at about $10.5 million and has been included in the division’s 2026 rate proposal, staff said; that WTD figure will be confirmed in the division’s rate and budget work.

Committee members asked about financial and legal risks if federal funding or other parties’ contributions change. Christie Elliott, Senior Deputy Prosecuting Attorney, said there are legal risks that would require confidential attorney‑client discussions; she noted that because EPA issued a 2024 administrative order to permit construction to start, work can continue under that order if necessary. Committee members asked about expected milestones (including whether the Department of Justice would sign and lodge the decree in May); staff said those scheduling and negotiation matters were appropriate for executive session and committed to follow up on timing and community‑engagement plans. Michael Galvin (WTD) said the performing parties are beginning joint community engagement planning and that the project engagement will be coordinated with other CSO and Duwamish‑area projects.

The committee moved to forward proposed ordinance 2025‑0084 with a due‑pass recommendation. The roll call recorded four ayes, no nos, and one excused member; the ordinance will be forwarded to the April 1, 2025 Council meeting and is slated for the consent agenda if there is no objection.