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Harbor Island and East Waterway Superfund Cleanup

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The Harbor Island Superfund Site is one of the first Superfund sites in the country, listed on the National Priorities List in 1983.

Harbor Island is a human-built, industrial island in Elliott Bay. Built in the early 1900s, the 420-acre island supports businesses that conduct commercial and industrial activities, including a former lead battery recycler, ocean and rail transport operations and petroleum fuel farm storage and operation. Prior operations at the site resulted in contaminated groundwater, sediment and soil with lead and other contaminants. 

The EPA divided the Harbor Island site into six smaller areas, known as “Operable Units” (OUs) to better address site cleanup. Cleanups have been completed at five of the OUs, and the remaining OU for cleanup is the East Waterway (EW).

Map showing the location of the East Waterway, the Lower Duwamish Superfund Site, and the Harbor Island Superfund site.
Map of the East Waterway, which is one-mile long and 157 acres. 

The human-built East Waterway stretches one mile and covers 157 acres. It was created by filling, dredging, and channeling during the construction of Harbor Island. Early industrial and commercial use of the East Waterway consisted of fish processing facilities, shipyards, and facilities with flour mills, grain elevators, lumber yards, and cold storage. Wharves constructed on creosoted piles were built in the early 1900s. Commercial and industrial use continued after the 1940s, including oil terminals, shipyards, rail transfer terminals, cold storage, lumber yards, metal recycling and transfer stations.

From these legacy uses, the sediment of the East Waterway is contaminated with high levels of pollutants including polychlorinated biphenyls, arsenic, carcinogenic polycyclic aromatic hydrocarbon, tributyltin, and mercury.

The maintained East Waterway remains one of the most active commercial and industrial waterways in the Pacific Northwest, serving multiple maritime shipping container terminals.  


Frequently Asked Questions

Q: Who is involved in the East Waterway cleanup?

A:  The EPA oversees the East Waterway cleanup, which is primarily conducted by the East Waterway Group (EWG), consisting of the Port of Seattle, the City of Seattle, and King County. The Port is leading the investigation work under a legal agreement with the EPA. The City of Seattle and King County are supporting the Port's efforts and along with the Port, are conducting source control measures in support of the superfund cleanup.

Q: What has been accomplished so far?

A: Since 2006, the EWG has worked collaboratively with the EPA to collect hundreds of sediment, tissue and water samples; perform human health and ecological risk assessments; perform hydrodynamic, propwash and food web modeling; and develop and compare potential cleanup actions for addressing contaminated sediment.

The EWG members and other entities have also performed investigations and cleanup of facilities and cleaned out drainage lines within storm drains and combined sewer systems in the EW basin.

In 2014, the Remedial Investigation (RI) was completed. Information gathered from the Remedial Investigation helps the EPA determine the best and most efficient ways to address the threats to human health and the environment from the East Waterway sediment. The data from the RI supported the analyses conducted in the Feasibility Study (FS). The FS was completed in 2019 and evaluated a range of options for cleaning up the contamination identified in the RI. The FS evaluated several cleanup options including removal of contaminants by dredging, capping over contaminants with an engineered clean sand cap; and  adding thin layers of sand to less contaminated areas where sediment does not move. There is  monitoring taking place to see if contaminant concentrations levels are decreasing over time.

In addition to the RI/FS work, in 2003-2005 (two dredge seasons) the Port performed an interim cleanup action under EPA oversight which involved dredging 200,000 cubic yards of contaminated sediments requiring upland disposal.  It was one of the first sediment cleanups performed in the Elliott Bay area and it used best management practices that included spill containment and water quality monitoring during the sediment dredging, storage and transport.

Q. What are the goals for the cleanup?

A: The cleanup is required due to pollutant levels in sediment that may pose unacceptable risks to human health and the environment. The East Waterway Group is committed to the fastest possible cleanup, significant long-term risk reduction, and moving forward in a way that improves conditions for fish, wildlife, and people. Through the RI and FS, the EPA has concluded that returning the industrial East Waterway to predevelopment, natural background conditions is not feasible. However, the cleanup actions outlined in the feasibility study will achieve significant, long-term risk reduction. 

Q: What happens next?

A: The EPA will use both the RI and FS reports to help prepare a proposed plan to clean up the East Waterway. The Proposed Plan will summarize cleanup alternatives and propose a preferred course of action.

The Proposed Plan is a draft and not a final decision. There will be a public comment period once the Proposed Plan is published. EWG has advocated for enhanced public participation for the East Waterway cleanup process and has asked the EPA to consult with the community on the public engagement process before the proposed plan is released. Once the public comment period on the Proposed Plan is complete, EPA will evaluate the input received. EPA’s final cleanup decision will be published in a Record of Decision, which will detail what cleanup work will be required.

Q. When will the cleanup be complete?

A: The Feasibility Study included cleanup alternatives that would take 3 – 5 years to design and 8 -10 years to construct following the release of the Record of Decision. Multiple construction seasons will be required to work within salmon protection windows. The East Waterway Group wants to get started with the cleanup of the waterway as expeditiously as possible, with a current target of completing remedial construction by 2035.

Q. Will we be able to eat the resident fish?

A: The East Waterway cleanup is expected to significantly reduce contaminants in the environment; however, similar to other local urban waterbodies, people will still not be able to safely consume unlimited amounts of resident seafood taken from the East Waterway after the cleanup.  This is largely because urban background levels of PCBs in water and sediment from upstream (Green River) will continue to impact seafood in the East Waterway.


Community Engagement

EPA manages the public engagement process for Superfund clean ups.  Visit the EPA website to find out the latest information about Harbor Island and, in particular, EPA cleanup activities, public meetings, and other information about the East Waterway. The EWG is also working to develop a website where the public can find information about the current status of the cleanup and current opportunities for engagement, which will be linked here when it is available.

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