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Commencement Bay is part of Puget Sound, a large waterway carved out by glaciers over several Ice Ages.  The Bay is surrounded by the City of Tacoma on three sides. The Puyallup River, which begins at Mount Rainier, flows into Commencement Bay, creating a large delta area, or tideflats.  The Hylebos Creek flows into the northeast end of the bay.

The Puyallup Tribe lived on the shores of Commencement Bay for thousands of years.  The tribe had several settlements along the Puyallup River delta by the time Euro-Americans arrived in the mid-1800s1.  Industrial growth began with sawmills for the plentiful, nearby timber.  In 1873, Commencement Bay became the western terminus of the Northern Pacific Railroad, driving further development. 

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A Changing Environment and a Toxic Legacy

Over the past 150 years, Commencement Bay has seen many changes. Development has meant filling in the tideflats to create industrial land, and dredging out waterways for boats and ships. This has dramatically changed the environment and reduced habitat for native species. Many of the industries that operated on the Bay also created long-term pollution issues. A large part of the problem is that much of the contamination happened before federal and state pollution laws were created.

Some of the pollution sources include:

  • The former Tacoma Asarco copper smelter produced slag, laden with toxic metals such as arsenic. This slag was used for road bed material in log sort yards and as fill on many other types of properties.

  • Sawmills and pulp mills created woodwaste. Some of this woodwaste, mixed with Asarco slag, was used as fill across the tideflats.

  • Refineries, tank farms, pipelines, and underground storage tanks have leaked petroleum products into soil, groundwater, and sediments. Petroleum contains hundreds of toxic chemicals that harm both humans and wildlife.

  • Coal gasification plants turned coal into energy-producing gas and useful byproducts, but left a mix of tar and chemical contamination.

  • Chemical plants, foundries, metal platers, and many other types of industries released toxins into the environment. These toxins include solvents such as perchloroethylene, dangerous metals such as chromium, and poly-chlorinated biphenyls (PCBs), which can cause a wide range of health problems, including cancer.

  • Older landfills in the tideflats have leaked many toxic substances into soil and groundwater. The Port of Tacoma is working to clean up the Tacoma Tideflats Landfill. They have already restored some of the land to natural habitat, creating Gog-le-hi-te Wetlands Park.

  • Boat yards and shipping create their own environmental problems. Many boats are coated with toxic tributyl tin (TBT). TBT can get into the environment when this coating flakes off of a boat, or during sandblasting when a boat is being repainted. Petroleum spills from boats also pose a risk to the bay.

  • Railroads can be sources of contamination, from petroleum spills and from arsenic-laden slag used to build railroad beds.

  • Some of the most difficult pollution to control comes from Tacoma’s hundreds of storm drains that empty directly into the bay.  Pollutants can include spilled oil and petroleum, lawn pesticides and fertilizers, pet waste, and more.  Ecology has resources for how to help protect our waters.

1. Tacoma Thumbnail History,

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Becoming a Superfund Site

In the early 1980s, Ecology staff began finding evidence of widespread contamination in Commencement Bay sediments.  It was clear that many upland sources were contributing to the pollution, and that major cleanup work would be needed to restore the bay.

In 1981, Commencement Bay was placed on the Superfund  program’s national interim priorities list—the top 115 priority hazardous waste sites in the country.  At that time, it was Washington’s highest priority site.  EPA and Ecology then worked out the Ecology—EPA Cooperative Agreement, giving Ecology the lead role in the investigation. 

In December of 1983, the Commencement Bay Nearshore/Tideflats  site was officially added to the National Priorities List (NPL).  The “site” included four main areas: the Asarco Smelter site and Ruston/North Tacoma Study Area; Tacoma Tar Pits; and the Tideflats Area. The first steps in the Superfund cleanup process included:

  • Remedial Investigation (1985) – Looked at nature and extent of contamination, and risks to human health and the environment.
  • Feasibility Study (1988) – Evaluated possible options for cleanup.
  • Record of Decision (1989) – This EPA document describes the selected cleanup remedies—site use restrictions, source control, natural recovery, sediment cleanup, and monitoring.

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Early Efforts: Source Control

Under EPA’s cleanup plan for Commencement Bay, Ecology was responsible for source identification and source control. Ecology inspectors first tried to identify all possible pollution sources around Commencement Bay. They went “door-to-door” in the tideflats, talking to facility owners, researching historical land uses, and taking environmental samples.

The next step was to try to reduce or eliminate all toxic releases to Commencement Bay before EPA began sediment cleanup. Any remaining toxic sources would only re-contaminate the cleanup area. Ecology worked with facility owners and operators to improve their chemical management and disposal practices.  Ecology also gave grant funding to the City of Tacoma to help manage pollution in stormwater.

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Cleaning Up Sediments

As Ecology identified sources and began source control, EPA planned for sediment cleanup. Sediment cleanup can involve:

  • Dredging up contaminated sediments and containing them in a disposal area;
  • Capping them in place with a layer of clean sediment; or
  • Allowing for natural recovery, where pollutants break down over time or disperse, or new sediments cover over contamination.

Commencement Bay was the first Superfund site in the nation to begin delisting cleaned up waterways. After 15 years of monitoring, St. Paul Waterway was taken off the National Priorities list in 1996. Sediment cleanup information is available for all of the waterways within the Superfund site.

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Where We Are Today

Today, Commencement Bay is a cleaner and healthier environment than in 1981, when it became a Superfund site. However, there is still much work to be done. Sediments continue to be monitored and work is ongoing at upland cleanup sites across the tideflats. Please visit the Cleanup Projects page for more information about upland cleanup sites. The City of Tacoma has taken the lead on a number of habitat restoration  projects around the bay, through an agreement with EPA.  Perhaps most importantly, agencies and the public are working together to help prevent future contamination. Please visit the Urban Waters Initiative page to learn more about preventing pollution.

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