The Superfund Process

King County partnerships

The Lower Duwamish Water Superfund cleanup builds upon decades of work by King County and its partners to improve water and sediment quality in the Lower Duwamish. The waterway is cleaner today than it has been in nearly a century.

King County participates in two primary groups working to restore the Lower Duwamish Waterway to health:

• The Source Control Work Group: The Washington State Department of Ecology leads the group, which consists of the EPA, King County, the City of Seattle, the Port of Seattle and other agencies. Members share information, discuss strategy, develop action plans, implement source control measures, and track their progress.
• The Lower Duwamish Waterway Group (LDWG): In 2000, the County joined with the Port of Seattle, City of Seattle and The Boeing Company to form LDWG in order to cooperatively work with the agencies to investigate and begin cleaning up contaminated sediments in the waterway. U.S. EPA then listed the Lower Duwamish as a Superfund site in 2001. Together, the four parties are helping to define a strategy for the cleanup. The overall goal of the cleanup is to develop a process for managing contaminated sediments in the waterway, and to reduce risks to fish, wildlife and people who use the river for recreation and tribal net fishing.

Highlights from LDWG's work include:

• Investment: King County has invested more than $250 million to date and has committed an additional $170 million to pay for cleanups and related efforts that are returning the Duwamish to health.
• Contaminated sediment cleanup: Cleaned up seven of the dirtiest acres of river bed, removing 65,000+ cubic yards. The City of Seattle and King County are investigating contamination and planning a cleanup of Slip 4 (external link).
• Tracing and controlling sources of pollution to the waterway sediments (river bed)
• Sampling and monitoring
• Habitat restoration -  restoring more than 25 acres of habitat along the waterway
• Reducing volume of combined sewer overflows (CSOs)

• Norfolk combined sewer overflow project: removed more than 5000 cubic yards of contaminated sediments. About 66,000 cubic yards of contaminated sediment was removed at the Duwamish combined sewer overflow and Diagonal storm drain.