South Lake Union cleanup

Aerial view of Seattle downtown with Lake Union in foreground

The South Lake Union neighborhood is between downtown Seattle and Lake Union. The area has a long history of industrial and commercial activities which contaminated the soil and groundwater. Currently, the area is undergoing extensive redevelopment as new buildings are constructed for commercial and residential use.

With many sites in a small area, contamination from different sources may mix in the groundwater. Also, construction work at one location may impact a nearby site. Ecology is looking at these sites as a whole to make sure that cleanup work will effectively protect people and the environment.

Cleanup progress

The 2026 cleanup summary has a printable version of this information

2024 to 2025

We completed:

  • Four environmental studies of cleanup sites (remedial investigations)
  • One report comparing cleanup options (feasibility study)
  • One plan for cleanup (cleanup action plan)
  • One new legal agreement for cleanup work
  • One site removed from the Contaminated Sites List

Previous work

We have already done substantial cleanup construction work in South Lake Union, and completed legal agreements, investigations, and plans necessary for more construction.

Many of the South Lake Union sites did some cleanup work under our Voluntary Cleanup Program before entering into legal agreements with Ecology.


Cleanup sites

Washington's environmental cleanup law defines the cleanup process.


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