Oakland Bay and Shelton Harbor Sediments


Ecology held a public comment period from February 15 to March 19, 2018 for the Shelton Harbor Interim Action Plan (IA) and State Environmental Policy Act (SEPA) Mitigated Determination of Nonsignificance determination.

Ecology received two comment letters, which did not lead to substantive changes. 

The comments and their responses are available now in the Responsiveness Summary.   To view an electronic copy of the responsiveness summary, click the following link:

Responsiveness Summary

If you have any questions regarding this cleanup site, please contact:

Joyce Mercuri, Cleanup Project Manager 

Email: Joyce.Mercuri@ecy.wa.gov 
Phone: 306-407-6260
Mailing Address: Washington Department of Ecology, PO Box 47775, Olympia, WA  98504 



We are working with Simpson Timber Company to clean up contamination from historic industrial activities in Shelton Harbor. A plan to clean up part of the site, called an Interim Action Plan, is available for public comment. The Interim Action Plan:

·       Describes the nature and extent of contamination at the Shelton Harbor sediment cleanup unit - the area addressed by the interim action.

·       Evaluates different cleanup options for portions of the site.

·       Proposes cleanup actions to protect people and the environment from contamination in the interim action areas.

We also reviewed information about the cleanup activities to see if they will have negative impacts on people or the environment. State Environmental Policy Act (SEPA) documents explain this review and are also available for public comment.

For more detailed information, click the link below to review a fact sheet or the Interim Action Work Plan. You can submit written comments to Joyce Mercuri by
email or mail from February 15th through March 19th.

Oakland Bay and Shelton Harbor Sediments Study Site
Please click on the photo for a larger view


In the summer of 2017, we made a formal legal agreement, called an agreed order, with the Simpson Timber Company (Simpson) to begin cleanup in Shelton Harbor. You can click the link below to read the document. The new agreed order requires Simpson to:

  • Describe the types and extent of contamination in Shelton Harbor through a remedial investigation.
  • Develop and carry out a partial cleanup plan called an interim action.
  • Evaluate cleanup options through a feasibility study.
  • Choose cleanup methods through a draft cleanup plan.

You can find the agreed order and a copy of the comments we received and our responses to them in the links below.


Extensive research into sediment contamination in Oakland Bay showed that contamination was most concentrated in Shelton Harbor. To address that contamination, we have defined a portion of the bay, the Shelton Harbor Sediment Cleanup Unit.

The Oakland Bay Sediment Investigation, detailed below, showed contamination from dioxin, excessive wood waste, and cPAHs (carcinogenic polycyclic aromatic hydrocarbons) in the harbor. The highest concentrations of these contaminants are in Shelton Harbor, at the western end of Oakland Bay.

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.


In 2008 and 2009, with support from the Puget Sound Initiative, Ecology’s Toxics Cleanup Program 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.

Ecology 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.

Industrial uses of Oakland Bay resulted in 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 Oakland Bay.


A report on the Oakland Bay Sediment Characterization Study was released for public review and comment in December 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.



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, or the full DOH health consultation report.



March 23, 2011

December 2010



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.


Ecology's Water Quality Program is currently developing a plan to address water quality problems in Oakland Bay, including fecal coliform bacteria.  For more information about this work visit http://www.ecy.wa.gov/programs/wq/tmdl/oakland_bay/index.html.

The Oakland Bay Clean Water District is a multi-agency coordinated effort to restore the health of Oakland Bay.  To learn more, visit: The Oakland Bay Clean Water District web site.

Other documents about Oakland Bay sediments 




For information about human health, contact:

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


Map showing site location as Mason County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 18051

Cleanup Site ID: 13007

Shelton, Mason County

Status: Cleanup Started   Get definitions of Status terminology

Joyce Mercuri
Project Manager
(360) 407-6260

Sheila Coughlan
Public Involvement Coordinator
(360) 407-6255

Document Repositories:

Southwest Regional Office
300 Desmond Dr SE
Lacey, 98503-1274

Shelton Library
710 W. Alder St.
Shelton, 98584