Oakland Bay and Shelton Harbor Sediments

Industrial uses of Oakland Bay caused sediment contamination in Shelton Harbor and surrounding areas. Chemicals, wood waste, and waste water from timber and wood product manufacturing industries have been discharged into the bay.

Extensive research showed that contamination was most concentrated in Shelton Harbor, at the west end of the bay. To address that contamination, we defined a portion of the bay as the Shelton Harbor Sediment Cleanup Unit.

Through this cleanup work, Ecology has an opportunity to contribute to the success of a planned habitat restoration project in Shelton Harbor. We plan to dovetail restoration with the first stages of cleanup work in order to:

• Make both projects more efficient
• Ensure that the restoration project is built on a foundation that meets state cleanup standards.

Legal agreement for cleanup

In the summer of 2017, we made a legal agreement, called an agreed order, with the Simpson Timber Company to begin cleanup in Shelton Harbor. The 2017 Agreed Order requires Simpson to:

• Study the site and describe the types and extent of contamination (a remedial investigation)
• Plan and carry out an early partial cleanup called an interim action.
• Evaluate cleanup options through a feasibility study.
• Choose cleanup methods and present a draft cleanup plan.

We accepted public comments on the draft agreement. Read our responses to comments on the 2017 Agreed order.

Interim action

In spring of 2018, Ecology accepted comments on Simpson's Interim Action Plan and a State Environmental Policy Act (SEPA) Mitigated Determination of Nonsignificance. We received two responses, which did not lead to major changes. Read our response to the interim action plan comments.

In 2008 and 2009, with support from the Puget Sound Initiative, Ecology investigated the health of the sediments in Oakland Bay. Sediment contamination can impact plants and animals that live in or around the contaminated sediment. Some contaminants can have broader impacts when they move through the food chain.

We chose Oakland Bay because Shelton Harbor has a history of heavy industrial use and previous studies showed evidence of contamination. In addition, Oakland Bay is one of the most productive shellfish growing areas in the country.

We released a report on the Oakland Bay Sediment Characterization Study or public review and comment in 2010. The full text of the report is available by clicking the links below. The Sediment Investigation Report contains information about:

• Location and amount of chemicals and wood waste in the sediment
• Amount of sediment movement and deposition in Shelton Harbor and Oakland Bay
• Potential effects of sediment contamination on the health of creatures living on or in the sediment
• Possible sources of dioxin found in sediment

If we removed every contaminant in South Puget Sound, would the sediment, air, and water entering the harbor re-contaminate the area? An update to the rule that guides our cleanup work in sediment (Chapter 173-204) introduced the concept of background chemical concentration levels to address questions like this.

Regional background includes chemical concentrations in sediment from diffuse sources, like regional stormwater or atmospheric deposition that are not linked to a specific source or release.

In 2018, we completed a study of the regional background levels of two contaminants found in Oakland Bay and Shelton Harbor. The South Puget Sound Regional Background study uses existing data from areas surrounding Squaxin Island; south of Harstine Island; and five inlets, including Henderson Inlet, Budd Inlet, Eld Inlet, Totten Inlet and Oakland Bay.

The results of this study, in combination with our understanding of the risk that contaminants pose to human health and the environment, help us decide cleanup levels and inform cleanup decisions in the area.

• South Puget Sound Regional Background Fact Sheet
• South Puget Sound Regional Background Report

According to a health consultation from the Department of Health, even people who eat large amounts of shellfish from Oakland bay are very unlikely to see harmful health effects from the shellfish. The health assessment also determined that touching, breathing in, or accidentally eating contaminated sediment from Oakland bay is very unlikely to harm people’s health.

Read a fact sheet describing the health consultation.

Ecology's Water Quality Program is currently developing a plan to address water quality problems in Oakland Bay, including fecal coliform bacteria. 

The Oakland Bay Clean Water District is a multi-agency coordinated effort to restore the health of Oakland Bay. 

Other documents about Oakland Bay sediments 

• Dioxin in Surface Water Sources to Oakland Bay (Mason County), May 2013
  A study done to determine whether creeks that flow in to Shelton Harbor or Oakland Bay might be a source of dioxins.
• Budd Inlet and Oakland Bay Dioxins and Furans, September, 2014
  Results of a study that asked whether cleaner sediment is slowly accumulating on top of deeper, more contaminated sediment.
• Oakland Bay Sediment Dioxin Source Study, December 2014
  An analysis of the dioxin/furan chemical results in Oakland Bay sediments to help Ecology understand the sources and locations of the contaminants.

For information about human health, contact:

Len O'Garro
Washington Department of Health
Email: Lenford.O'Garro@doh.wa.gov
Phone: 360-236-3376