Posted on January 15, 2025
The U.S. Environmental Protection Agency and the members of the Lower Duwamish Waterway Group, which includes King County, the City of Seattle, and Boeing, have begun sediment cleanup of the Lower Duwamish Waterway Superfund site.
Construction activities for the cleanup will start in the waterway’s upper reach, which extends from the South 102nd Street bridge downstream to the Duwamish Waterway Park. King County has hired Pacific Pile and Marine from South Park as the lead contractor for cleanup construction in the upper reach.
Over the next three years, in-water cleanup activities for this segment will occur during construction seasons from October to February, ending in February 2027. Once complete, construction will continue downstream toward the south end of Harbor Island over the next decade.
Over a century of urbanization and industrial activity has polluted the sediment at the bottom of the waterway. Contaminants found in the sediment include polychlorinated biphenyls (PCBs), heavy metals such as arsenic, lead, zinc, and other types of contaminants, including dioxins, furans, and polycyclic aromatic hydrocarbons (PAHs).
Today, people are advised not to eat fish and shellfish that live year-round in the waterway. Salmon caught in the Lower Duwamish Waterway are a safe choice to eat because they only spend a short time in the river as they migrate through. The members of the LDWG are cleaning up this contamination to improve the waterway’s ecosystem and protect people who live, work, and play along the river.
