Lower Duwamish Waterway Superfund Settlement Summary
On March 4, 2026, the U.S. Environmental Protection Agency (EPA), U.S. Department of Justice (DOJ) and the state of Washington, reached a settlement agreement with more than 100 potentially responsible parties to address hazardous substances released into the Lower Duwamish Waterway, a five-mile segment of the city of Seattle’s only river.
Under the settlement, the Lower Duwamish Waterway Group – which consists of The Boeing Company, city of Seattle, and King County – agreed to design and perform EPA’s selected cleanup plan for the in-water portion of the Lower Duwamish Waterway Superfund site. The cleanup work will address about 177 acres in the waterway through dredging and capping and other measures to clean up the most contaminated parts of the Waterway.
The work is expected to take at least 10 years and will significantly reduce the risks associated with eating resident fish and shellfish, as well as direct contact with river sediments. The value of the settlement is about $668 million. To help fund the required work, the Lower Duwamish Waterway Group will receive about $130 million from other private responsible parties and about $140 million from settling federal agencies.
The EPA cleanup complements the work of state, county, and city agencies, employing cooperative federalism to improve the health of the Duwamish watershed and its surrounding communities.
About the Lower Duwamish Waterway Group
The Lower Duwamish Waterway Group is a public-private partnership between several of the potentially responsible parties, including The Boeing Company, the city of Seattle, and King County. The group is implementing the remedy at the Lower Duwamish Waterway Superfund site. The Lower Duwamish Waterway Group began in-water construction in November of 2024 under a unilateral administrative order, so that cleanup would not be delayed by fish migration seasons in the waterway.
Information about Lower Duwamish Waterway Superfund Site
The Lower Duwamish Waterway Superfund site is a five-mile segment of Seattle’s only river, the Duwamish that flows between the Georgetown and South Park neighborhoods and through the industrial core of Seattle into Elliott Bay
The Lower Duwamish Waterway has served as Seattle’s major industrial corridor since the early 1900s, causing the Waterway’s river bottom to be contaminated with toxic chemicals from many sources, ranging from stormwater runoff, wastewater, and industrial practices. The Lower Duwamish Waterway became a Superfund site in 2001. EPA has identified 41 hazardous substances in sediments within the waterway that pose significant risks to human health and the environment, including polychlorinated biphenyls (PCBs), arsenic, carcinogenic polycyclic aromatic hydrocarbons, dioxins, and furans.
EPA administers the sediment cleanup in the waterway, and the Washington Department of Ecology is responsible for controlling sources of pollution to the waterway. More information about the Site is available from the agency’s Lower Duwamish Waterway site profile webpage.
Summary of the Remedial Design/Remedial Action Consent Decree
The consent decree requires the cleanup of a five-mile segment of the Lower Duwamish River, extending from Seattle into Tukwila, Washington. Under the consent decree, the Lower Duwamish Waterway Group will perform remedial design and remedial action at the site. Response costs, estimated at over $668 million, will be funded largely by the group. Numerous other responsible parties will pay a total of about $130 million. Several settling federal agencies will pay about $140 million to help fund the work performed by the group.
EPA secured financial assurance from the Lower Duwamish Waterway Group, in the amount of approximately $668M, in case EPA needs to take over remedial action work. Financial assurance provisions in Superfund settlements and orders help ensure that responsible parties, and not public funding sources, bear the financial burden of completing Superfund cleanups.
Comment Period
The proposed consent decree, lodged in the U.S. District Court for the Western District of Washington, is subject to a 30-day comment period and final court approval. Information on submitting comments -and access to the settlement agreement is available on the Justice Department’s Proposed Consent Decree webpage.
Contact Information
Nick Vidargas
Acting Land Law Branch Manager
Office of Regional Counsel, Region 10
vidargas.nick@epa.gov
Reagan McQueen
Office of Site Remediation Enforcement
Office of Enforcement and Compliance Assurance
mcqueen.reagan@epa.gov
Adeline Sporleder
Office of Site Remediation Enforcement
Office of Enforcement and Compliance Assurance
sporleder.adeline@epa.gov