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Toxics Cleanup Program

Photo:  Lower Duwamish Waterway


The Washington State Department of Ecology (Ecology) and the U.S. Environmental Protection Agency (EPA) are working to clean up contaminated sediments and control sources of recontamination in the Lower Duwamish Waterway under an Administrative Order on Consent with the City of Seattle, King County, the Port of Seattle, and The Boeing Company.

The Lower Duwamish Waterway site is an approximately 5 mile portion of the Lower Duwamish River which flows into Elliott Bay.

The sediments along the river contain a wide range of contaminants due to years of industrial activity and run off from residential areas.  These contaminants include PCBs (polychlorinated biphenyls), PAHs (polycyclic aromatic hydrocarbons), chlorinated dioxins & furans, arsenic and other metals, pesticides and phthalates.

EPA is leading the sediment contamination investigation for the Lower Duwamish Waterway site with support from Ecology. In 2001, EPA added the Lower Duwamish Waterway site to the Superfund National Priorities List; Ecology added the site to the Washington Hazardous Sites List in 2002. More information on the Lower Duwamish Waterway Superfund site can be found on EPA’s web page: Lower Duwamish Waterway site. More information on the sediment contamination clean up can be found on the following sites: Duwamish River Cleanup Coalition ( and the Lower Duwamish Work Group (

Ecology is leading the efforts to control sources of sediment pollution in the Lower Duwamish Waterway in cooperation with the City of Seattle, King County and EPA.

Source Control is the process of working to find and control releases of pollution to waterway sediments to prepare for cleanup and prevent sediment recontamination. Finding and controlling sources is difficult, and even with aggressive source control some recontamination may occur.

The Phase 1 remedial investigation report identified seven areas along the river as candidates for high priority sediment cleanup.

The initial source control focus has been on four early action areas:  Duwamish/Diagonal, Norfolk CSO/SD, Terminal 117, and Slip 4; see site map.

The EPA and Ecology held a public comment period on plans for the cleanup of Lower Duwamish Waterway sediments from February 28 – June 13, 2013. Ecology’s public comment period presentation is available in English and Spanish. The documents presented for public review include:

  1. Ecology’s Source Control Strategy
    Ecology’s long term plan for reducing sources of pollution and how the government agencies will work together

  2. EPA’s Proposed Plan for sediment cleanup
    EPA’s recommendation for how to clean up the sediments in the Lower Duwamish Waterway

  3. EPA’s Environmental Justice Analysis
    EPA’s analysis of possible impacts of the cleanup options on the Local community

Ecology and EPA are reviewing all of the comments submitted on these documents. Ecology will respond to all comments related to Ecology’s Source Control Strategy and EPA will respond to all comments related to the Proposed Plan and the Environmental Justice Analysis. Responses will be posted online after the comment period. 

Interagency Source Control Work Group

Ecology is leading the interagency Source Control Work Group (SCWG). The SCWG shares information, discusses strategy, develops action plans, implements source control measures, and tracks progress. The SCWG includes:

Ø Ecology: Lead for source control at properties that discharge directly to the waterway and for source control work at upland contaminated properties;

City of Seattle: Lead for source control within their storm drain system;

Ø King County: Lead for source control for discharges to wastewater or combined wastewater and storm water systems;

Ø EPA: Lead for Boeing Plant 2, Terminal 117, Slip 4 sediments, and Rhone/Poulenc cleanup sites; provides technical assistance, source control coordination with EPA sediment investigation and cleanup activities.

Ecology and the SCWG wrote the original Source Control Strategy for the Lower Duwamish Waterway.

We will continue to expand this web page as additional information and documents become available. Please check the menu at the left regularly for new information on source control activities in the Lower Duwamish Waterway.


Photo:  Lower Duwamish Waterway


Bob Warren
Executive Manager
(425) 649-7054

Ron Timm
Site Manager
(425) 649-7185 

Dan Cargill,
Source Control Project Manager
(425) 649-7023

Meg Bommarito
Project Planner
(425) 649-7256