Cleaning up: Cleanup of shoreline and sediment moving forward for Seattle’s Gas Works Park

Gas Works Park, on the north shore of Lake Union, was once home to a gas manufacturing plant. The plant was constructed in 1907 and operated until 1956, providing fuel for the growing population of Seattle. Prior to industrialization, the area was home to three indigenous communities — the Duwamish, Hachooabsh, and Shilsholes.

Old photo of gasworks park, with giant tanks upland, machinery near the water, and boats moored.

The gas works in 1965.

The plant and other industrial activities contaminated soil, groundwater, and sediment. Much of the contamination in the upland area was addressed through multiple cleanup actions completed between 1971 and 2020, and restrictions are in place to keep people from being exposed to contamination still onsite. Contaminated soil and groundwater in certain shoreline areas and contaminated in-water sediment still require cleanup, which is moving forward.

The sediment cleanup area includes the shoreline of gasworks park and extends out into lake Washington, with the largest area in southwest

We invite you to attend a public meeting to learn more and review a cleanup action plan and associated documents. The plan calls for removing and capping shoreline soil, treating shoreline groundwater, dredging sediment, capping sediment, monitoring, and administrative site use controls.

This plan is part of a legal agreement between Ecology, the City of Seattle, and Puget Sound Energy. The following documents are available for review:

  • Cleanup Action Plan: describes Ecology’s selected cleanup action to address remaining contamination.
  • Consent Decree (legal agreement): requires the city and PSE to develop detailed design documents and construct the cleanup action described in the cleanup action plan.
  • State Environmental Policy Act-Determination of Non-Significance: Ecology determination that the cleanup action is not likely to have a significant adverse environmental impact.

Online public meeting

Ecology will host an online public meeting using Zoom to provide project information and answer questions. There will be interpreters available in Spanish, Chinese, and Tagalog. Call-in options are available when registering from Ecology’s webpage.

Wednesday, June 28, 2023:

  • 6:30–7:30 p.m. Presentation
  • 7:30 p.m. Questions and answers, as needed

To learn more about the site, the cleanup action plan, register and join the meeting, and comment on the documents, visit our Gas Works Park webpage.

Cost and funding

The cleanup action is expected to cost about $73 million. The city and PSE are funding partners for the cleanup. The city is eligible for reimbursement of up to half of their costs from Ecology through the state’s remedial action grant program. This funding helps to pay to clean up publicly owned sites. The Legislature funds the grant program with revenues from a tax on hazardous substances.