Lower Duwamish River

Cutting through south Seattle, the Duwamish is an industrial river.
Cutting through south Seattle, the Duwamish is an industrial river.


Rebecca Hoff
NOAA Office of Response and Restoration
Seattle, WA 98115
(206) 526-6276

Case Documents

Lower Duwamish River

Hazardous Waste Site | Washington State | Mid-20th Century

What Happened?

The Duwamish River was once a wide, meandering river with large areas of mudflats and marshes. By the 1940s, channelization and filling had transformed the 9-mile estuary into a 5-mile industrial waterway. This process destroyed 97 percent of the original habitat.

The lower Duwamish River is still highly developed, with many industrial and commercial facilities lining its banks. Hazardous substances have been released since the early 1900s, resulting in injuries to fish, birds, wildlife, and their habitats.

What Were the Impacts?

We are currently assessing impacts to:

  • Wildlife, including fish, birds, mammals.
  • Water and sediment.
  • Recreational uses, including fishing.

What’s Happening Now?

Cleanup of the Lower Duwamish River has begun, and will continue for many years. But cleanup alone will not restore the salmon and other resources that have been impacted by past contamination. In order to restore these injured resources, additional habitat must be restored. This is especially true for the survival and recovery of threatened fish species, including the Puget Sound Chinook salmon and Puget Sound Steelhead. The young of these species spend time in this part of the Duwamish River as they transition from freshwater to saltwater.

In 2013, the trustees completed a final Restoration Plan (PDF, 124 pg). In 2014, as part of a NRDA settlement, the Boeing Company constructed one of the largest restoration projects on the Lower Duwamish River—almost five acres of mudflat, marsh, and riparian vegetation, providing habitat for fish and wildlife. The company Bluefield Holdings, Inc. has also completed a restoration project and plans to sell credits derived from the project to potentially responsible parties to address injuries to natural resources. We are planning additional projects to restore mudflats, marshes, and shoreline vegetation on the river. In 2016 a workshop report was published regarding habitat lessons learned on the Lower Duwamish River (PDF, 37 pg).

On July 31, 2018 the co-trustees announced a 30-day comment period for the Lower Duwamish Natural Resources Injury Assessment Plan (PDF, 79 pg). The updated plan includes the status of the natural resource damage assessment, information regarding the trustees’ emphasis on specific natural resources and hazardous substances, methods and metrics for quantifying contaminant-related injuries, and the specific studies the trustees have identified to support the damage assessment. The trustees will consider the public comments received, and will release a final injury assessment plan by late 2018 or 2019.

Last updated July 31, 2018