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The Swan Island Basin Remedial Design Group is working to advance the cleanup design of the Swan Island Basin area of the Portland Harbor Superfund Site

Sampling

In 2022 and 2023 nearly 2,500 environmental samples were collected in the Swan Island Basin Project Area from riverbanks, sediments, and stormwater. In addition, hydrodynamic, geotechnical, and habitat conditions were studied. The information gathered will be analyzed and used to design the remedy for the Swan Island Basin Project Area. The remedial design process entails development of a series of evaluation and design reports culminating in the proposed design that will be published in a Remedial Design Report, which is expected to be completed around the end of 2026.

An acoustic doppler current profiler (ADCP) is used to measure how fast water is moving in Swan Island Basin

The Swan Island Basin is the in-water area adjacent to the Swan Island and Mocks Bottom upland areas. These historical areas of Portland have long been tied to the city’s economic vitality and hard-working ethos. Like many areas around the U.S., that history also includes the use of materials that were later identified as harmful to the environment and human health. The Swan Island Basin Remedial Design Group is working to advance the cleanup design of the Swan Island Basin Project Area of the Portland Harbor Superfund Site.

A hundred years of extensive use of the Swan Island Basin for naval, industrial, commercial, including log storage, and municipal activities have contributed to historical releases of contaminants to the sediments within the Swan Island Basin Project Area.  Activities being conducted by those currently operating in and around the Swan Island Basin are subject to strict environmental regulations.  For example, ongoing industrial discharges to the Basin are now carried out in accordance with applicable permits and are subject to oversight by local, state, and federal agencies.

Map showing Swan Island Basin within the northern Willamette River.
Map showing where Swan Island Basin is located around Mock's Bottom, Tualatin Mountains, and Swan Island.

Several public and private members of the Swan Island Basin community are working on a detailed cleanup design plan for the 117-acre, mile-long Swan Island Basin. These parties are committed to maintaining a clean, safe place to continue the region’s history of living-wage industrial work. The plan is expected in 2026 and cleanup activities will occur after that. The party or parties that will conduct the cleanup activities have not yet been identified. The remedial design process includes conducting a pre-design sampling investigation and preparing a report to describe the current extent of contamination. This report will help the U.S. Environmental Protection Agency (EPA) determine the most effective cleanup plan for the Swan Island Basin Project area, as required by the EPA’s 2017 Record of Decision (cleanup plan) for the Portland Harbor Superfund Site.

FAQs

1. What is the Swan Island Basin?

The Swan Island Basin is a 117-acre, mile-long in-water area on the east side of the Willamette River located north of downtown Portland.  The Swan Island Basin and surrounding upland areas (Mocks Bottom and Swan Island) have been a major industrial location for commerce since the1920s.  Originally an island with channels on both sides, Swan Island was connected to the east side of the Willamette in the 1920s by filling part of the east channel to create a causeway.  Swan Island was the original site of the Portland airport until the 1940s.  During World War II, at the request of the U.S. government, a major shipyard was constructed with worker housing to support the war effort.  After the war, Swan Island and the adjacent Mocks Bottom area became a major center in Portland for ship repair, industrial distribution, warehousing, commercial and manufacturing activities.

2. What is a Remedial Design and why is it necessary?

The Swan Island Basin Project Area is a part of the Portland Harbor Superfund Site. In 2017, the U.S. Environmental Protection Agency (EPA) issued a cleanup plan (Record of Decision) that includes the Swan Island Basin Project Area. The current step in the cleanup process is the preparation of a detailed Remedial Design, including pre-design sampling and the preparation of a report. This report will describe the current extent of contamination and will be used to help identify the most effective cleanup technologies in a manner consistent with the 2017 Record of Decision. The evaluation and application of cleanup technologies to specific areas of the Swan Island Basin will be documented in a series of design reports that will comprise the detailed remedial design. The Remedial Design process began in 2021 and is expected to take approximately five years.

3. What activities caused the contamination?

Historical industrial, commercial, military, and municipal activities dating back to the 1920s resulted in releases of contaminants to the sediments within the Swan Island Basin Project Area.  Historical sources associated with the existing contamination include shipbuilding, vessel repair, and dismantling; chemical blending and storage; metal recycling and fabrication; electrical equipment; placement of contaminated dredge material; and discharge of stormwater from industrial, commercial, and transportation land uses.  

4. What are the risks to human health and the environment from contamination in the area?

Based on ecological and human health risk assessments, the risks to humans are mainly from the consumption of resident Willamette River fish (bass, carp) over a 30-year period.  Risks to ecological health are mainly to benthic critters in the sediments such as worms and crayfish.  The primary contaminants of concern for the Swan Island Basin Project Area are polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dioxins and furans, and DDx (product of the pesticide DDT).  

5. Who is overseeing the Remedial Design and who is conducting the work?

EPA oversees the cleanup process within the river (water and sediments) and the Oregon Department of Environmental Quality (DEQ) oversees the cleanup of upland properties and regulates pollution sources to the river that may pose a risk of recontamination of the sediments after cleanup.  A group of 11 potentially responsible parties (both government and private) have voluntarily stepped up to fund the Remedial Design within the Swan Island Basin Project Area.  The party or parties that will conduct the subsequent cleanup activities have not yet been identified. 

6. What happens in the Remedial Design process?

EPA’s Record of Decision determined that clean up actions are needed to reduce the risks from contamination in the Swan Island Basin Project Area. The Remedial Design will more precisely determine the location of the contamination (sampling of sediments), evaluate the potential for recontamination (sampling of stormwater and riverbanks) and will include geotechnical, structural, chemical, and biological evaluations to help determine the technologies (dredging, capping, natural recovery) that should be used to reduce risks within the Swan Island Basin Area. Construction of the remedy depends on the detailed design that will be developed over the next few years.

7. What types of sampling has taken place to determine the Remedial Design?

Environmental samples of river water, stormwater, river bottom sediments, and riverbank soil will provide the database for analysis of the most appropriate remedial design. The analysis and evaluation of all collected environmental samples is ongoing and the final design report will be completed around the end of 2026.

8. What technologies will be evaluated in the remedial design?

There are several technologies used to lower risks from sediment contamination, including capping, dredging, and expediting the natural recovery of the area over time.  All technologies will be evaluated in the remedial design process before the final design is selected.  The final design for the cleanup is expected to use a combination of technologies. 

9. Will the Remedial Design process include public involvement?

Yes. The federal Superfund law requires public involvement to be conducted by EPA for the Portland Harbor Superfund Site. The parties preparing the Remedial Design Report for the Swan Island Basin Area Project will work with EPA to keep the community informed and up to date about the remedial design progress, and how the remedial design will reduce contamination risks at the site.

10. When will actual cleanup of the contamination at Swan Island take place?

Once the remedial design is complete, cleanup activities will be performed under an agreement that will be negotiated between potentially responsible parties and the United States. The Portland Harbor Superfund Site contains many areas that will require cleanup, so the sequencing of cleanup work will be planned to avoid recontamination.  The cleanup will also need to be planned to limit impacts to migrating fish and recreational activities, and to minimize disruptions to harbor businesses and public access.

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