Superfund Site Profile

Harbor Island is an industrial island in Seattle, Washington's Elliott Bay. Built in the early 1900s, the 420-acre island supports businesses that conduct commercial and industrial activities, including ocean and rail transport operations. Site operations contaminated groundwater, sediment and soil with lead and other contaminants. Many Superfund sites like Harbor Island are large and complicated. These sites are often broken up into smaller areas to make cleanup easier and more manageable. These areas are called "Operable Units" or OUs. The EPA divided the site into six OUs, to better address site cleanup. The entire island and associated sediments are designated as the Superfund site. Cleanup decisions have been made at five OUs, and the remaining OU for cleanup is the East Waterway.

The East Waterway (EW) is a maintained waterway that was created during the construction of Harbor Island. Since the creation of Harbor Island, the original estuarine mudflat area has been either filled or dredged and channelized to create the EW. Early industrial and commercial use of the EW consisted of fish processing facilities, shipyards, and facilities with flour mills, grain elevators, lumber yards, and cold storage originally focused on the eastern shore. Wharves constructed on creosoted piles were built in the early 1900s along both sides of the EW. Commercial and industrial use continued after the 1940s on both sides of the EW, including oil terminals, shipyards, rail transfer terminals, cold storage, lumber yards, and sand and gravel transfer stations. From these uses, the mud of the EW is contaminated with high levels of pollutants including polychlorinated biphenyls (PCBs), arsenic, carcinogenic polycyclic aromatic hydrocarbon (cPAHs), tributyltin (TBT), and mercury. The potential sources of contaminants are both historical and from potentially ongoing sources.


Contaminated Ground
Water Status
Under Control
Site-Wide Ready for
Anticipated Use?