(King County photo, 2024 cleanup season)

The second of three seasons of in-water Duwamish River cleanup is about to begin. This is for the removal of contaminated sediment, in the works for decades, involving Boeing, the City of Seattle, and King County. Here’s the overview:

Construction in the upper reach, the southernmost two miles of the site, is scheduled to occur from October to February for three years, ending in February 2027. In-water construction activities are restricted to these months to protect certain fish species. LDWG completed in-water work for the first construction season from November 2024 – February 2025, with the second season beginning October 1, 2025.

Beginning October 1, the construction contractor will begin dredging contaminated sediment near the South Park Bridge and Duwamish River People’s Park.

Compared to the first construction season, cleanup activities this season will be more visible as the work moves closer to the South Park Bridge, homes, parks, and marinas. The community can expect multiple barges and equipment working on the water, lights for safe work during dark hours, and typical construction equipment noise.

Season 2 construction hours will be weekdays and Saturdays and will occur during both the daytime and nighttime. Work hours will vary based on factors, such as tides and the type of work being conducted (e.g., dredging or placing clean material). Work will be coordinated with Tribal fishing. During the first three weeks of October, in-water construction work is not currently planned for Mondays and Tuesdays when Tribal fishing is most active.

The dredged sediment goes by barge to a landfill on the Columbia River. More background on the contamination and cleanup are here. Cleanup-work updates will be on this website, including upcoming dates – not yet finalized (we’re told the ones currently listed online are likely to change) – for South Park Bridge closures.