Menu Home

Duwamish Cleanup

The Lower Duwamish Waterway is Seattle’s only river. The river supports commerce and employment for our economy, provides important recreation fishing and tribal cultural heritage resources, and is a critical estuarine environment for salmon and wildlife. The Duwamish industrial area has played a crucial role in developing our region’s economy for over a hundred years: today local industries employ over 100,000 people and support more than 25% of the manufacturing in King County.

In 2001, the Environmental Protection Agency (EPA) listed the Lower Duwamish Waterway as a Superfund site in need of cleanup as a result of contamination stemming from nearly a century of industrial activities and toxic discharges to the river. Primary contaminants of concern are polychlorinated biphenyls (PCBs), carcinogenic polycyclic aromatic hydrocarbons (cPAHs), arsenic, and dioxin/furans. In 2014, the EPA developed a detailed and comprehensive cleanup plan, called a Record of Decision (ROD), which along with early active area cleanups that have already occurred, is expected to reduce contamination levels by at least 90%.

Four organizations – the Port of Seattle, King County, the City of Seattle, and The Boeing Company – have been working together as the Lower Duwamish Waterway Group, or LDWG, alongside EPA and the Department of Ecology to investigate and address contamination at the Superfund Site.


Q: How is the cleanup being accomplished?

The Port, along with our LDWG partners, is working under a voluntary agreement with EPA and the Washington State Department of Ecology (Ecology) to investigate and evaluate cleanup options for the LDW. EPA is overseeing the sediment cleanup and Ecology is leading the effort to control current sources of upland pollution from entering the waterway. Each of the LDWG members also have an active role in working with Ecology to control remaining upland sources of pollution. LDWG also identified some of the most contaminated areas where they could start early cleanups, called Early Action Areas.

Q: What has been accomplished so far?

The Port’s goals are to protect public health, improve water quality, and restore vital areas of the river environment while ensuring the Lower Duwamish Waterway remains a vibrant urban working waterway. To date, LDWG has invested over $50 million dollars on scientific studies and data collection and over $200 million on the cleanup of Early Action Areas, which were identified early on as some of the most contaminated areas in the Lower Duwamish Waterway. The cleanup of these Early Action Areas has reduced PCB concentrations in the waterway sediments by 50%. The Port of Seattle’s Early Action is Terminal 117, which is in the South Park neighborhood. Visit the Terminal 117 page to learn more about that clean-up and future plans for the site.

Q: How can I learn more specific details of the cleanup plan?

More information and documents on the Lower Duwamish Waterway cleanup can be found on LDWG's website.  

Current Cleanup Activities

The Port and LDWG are committed to keeping the Lower Duwamish Waterway cleanup effort on schedule and are currently working on many activities to address the cleanup.

Enhanced Natural Recovery Activated Carbon Pilot Study

LDWG is performing a pilot study of an innovative cleanup technology using activated carbon to trap contaminants (e.g., PCBs) in sediments in order to prevent them from entering the food chain. The study will test the theory that pollutants are trapped by activated carbon that is mixed in a thin layer of clean material (either sand or gravely sand) and placed over existing contaminated sediments.  The study will also determine whether the carbon has negative effects on the animals that live in the sediment that make up the base of the food chain. The study is being carried out in three study plots on the Lower Duwamish Waterway representing three different river conditions. If successful, activated carbon can be used as an additional cleanup technology in areas where it is appropriate with EPA approval. This work will be completed by the end of 2020

Community Awareness about the Risks of Eating Resident Seafood

There continue to be human health risks associated with eating resident seafood (i.e., fish and shellfish that live in the river year-round, such as crabs, sole, perch) from the river. LDWG is collaborating with EPA and Public Health Seattle-King County to educate community members and fishers about the risks of consuming seafood from the Duwamish River. Community-based educators are teaching local fishers and nearby communities about safe fish preparation practices. This work will continue for several years after the cleanup has been completed or until resident seafood can safely be eaten from the Lower Duwamish Waterway.

Salmon are ok to eat and are the healthiest choice because they only spend a short time in the waterway. Visit the Public Health Seattle-King County’s website for more information on catching and preparing fish caught from the Lower Duwamish Waterway.

Baseline Monitoring/Pre-design

By early 2019, LDWG will be wrapping up the baseline monitoring and pre-design phases of the cleanup process. The data collected and evaluated during this phase are crucial for measuring the success of the larger sediment cleanup and source control efforts. The data collected in 2017 and 2018 reflect conditions following the Early Action Area sediment cleanups and will be used for long-term monitoring and to evaluate the overall performance of the final cleanup. The baseline work also assesses natural recovery, supports source control, and provides a strategy for the cleanup design.

Cleanup Design

EPA’s ROD anticipates dividing the Lower Duwamish Waterway cleanup into thirds for purposes of design and implementation, moving downstream from south to north. LDWG will begin designing the cleanup of the upper third in 2019. This design process will determine the specific locations and methods for cleaning up this section of the river. Scientists will gather data and engineers will use this data to create detailed plans for applying various cleanup technologies to meet the requirements set forth in the 2014 ROD. EPA has developed a “Community Roundtable” process that will allow information sharing and early input to design, with the goal of reducing impacts on local communities. To learn more and get involved, visit EPA's website.

Related to Duwamish Cleanup

Back to Top