The Duwamish has been a center of Seattle’s growth since the late 1800s when the winding river was straightened into a shipping channel to better support industry.
Development helped the region grow and flourish, but polluted the river with industrial waste, stormwater runoff and overflows of raw sewage during heavy rains.
In 2001, the U.S. Environmental Protection Agency (EPA) classified the Duwamish as a Superfund pollution site . Superfund is a program that finds and requires clean up of contaminated areas that are unsafe for people and the environment. While King County is working closely with the Superfund program, we are also doing additional work to restore the Duwamish.
King County and its partners are already making great progress towards cleaning up the river through early action projects. In 2004, King County successfully removed 66,000 cubic yards of contaminated sediment from the river as part of the Duwamish Diagonal cleanup.
City of Seattle just completed the cleanup of Slip 4. Boeing is doing associated cleanup and habitat restoration work. Port of Seattle is cleaning up the Terminal 117 site. These actions will address half of the historical contamination in the waterway. Superfund will address what's left.
Superfund cleanup timeline
|Lower Duwamish Waterway Group (LDWG) formed||2000|
|Initial assessments made||2000-2003|
|EPA proposes cleanup plan||2013|
|EPA cleanup decision||2014|
|Pre-Design work by LDWG||2014-2019|
|Negotiate Consent Decree||2018-2019|
|Cleanup activities begin (estimate)||2023|
|Full cleanup complete (estimate)||2030|
Who is in charge of the cleanup?
U.S. Environmental Protection Agency and the Washington State Department of Ecology are in charge, but we can all get involved. This includes King County.
Pollutants of Concern
PCBs and other carcinogens
Oil and hydrocarbons
Heavy metals including mercury
Poisons including dioxin, pesticides and arsenic
- Memo: Analysis of Transport Alternatives for Lower Duwamish Cleanup , January 14, 2014
Your role to clean up the Duwamish
Everybody has a role to play in cleaning up the Duwamish and keeping it clean. Visit “How can I help the Duwamish” to find out how your everyday actions can impact our Duwamish.
For more information
For more information about the Duwamish environmental cleanup process, please contact Caryn Sengupta.