image:Sailboat on Puget Sound


North Olympic Peninsula Regional Background Study

Located on the Strait of Juan de Fuca on the North Olympic Peninsula, Port Angeles Harbor is one of seven bays identified by the Puget Sound Initiative for priority cleanup.  In the 2013 revision of the Sediment Management Standards (SMS) rule, Chapter 173-204 WAC, Ecology developed the concept of regional background. 

On April 27, 2016 Ecology rolled out Final North Olympic Peninsula Regional Background Sediment Characterization Study. The chemical concentration levels developed in this study will be used to establish the upper cap for sediment cleanup levels, inform cleanup decisions, and identify potential areas of sediment contamination that may require cleanup in the future. 

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

The North Olympic Peninsula regional background study extends from Port Angeles Harbor in the west to Port Townsend Bay in the east (see map below). The study will help us set future cleanup levels in this region. We will compare regional background chemicals with chemical levels in Port Angeles Harbor. This will help us evaluate options for cleaning up the harbor. In the future, we may also use these regional background levels for comparisons with Port Townsend Bay and other bays along the north Olympic Peninsula.

Learn more! Technical workshops in Port Angeles and Port Townsend April 27th, 2016

Ecology staff will be available to discuss this study and answer questions. Workshops will include a presentation, question and answer session, and open house.

Port Angeles
5:30 – 7:00 PM
Elwha Klallam Heritage Training Center
401 East First Street, Port Angeles

Port Townsend
11:30 AM - 1:00 PM
Fort Worden Seminar Room
200 Battery Way, Port Townsend

Regional background data and reports:

Regional Background Study Area

Photo:  North Olymic Regional Background Study Area
      North Olympic Regional  Background Study Area

Why we did not initially sample in Port Angeles Harbor:

  • Sediment contamination in the harbor is from identifiable source areas in both the eastern and western harbor. The source areas influence most of the harbor.
  • Investigations of this contamination for cleanup are underway and study areas cover most of the harbor. The remaining area is too small to allow for complete regional background sampling and has a much coarser sediment particle size than most of the harbor.
  • When combined sewer overflows (CSOs) in Port Angeles drained into the harbor, they likely carried material containing dioxins/furans from hog fuel boilers from upland areas into the harbor. Because these dioxins/furans were from point sources, not urban diffuse sources, this contribution is not part of regional background.
  • The City of Port Angeles is working on a CSO improvement project to eliminate discharge events by routing the CSOs to the waste water treatment plant. Once completed, the project is expected to eliminate or greatly reduce upland dioxins/furans and other urban contaminants entering the harbor from street runoff.

For these reasons we did not initially collect samples or use existing data from Port Angeles Harbor to develop regional background.

We took samples in Dungeness Bay, Sequim Bay, Discovery Bay, and Port Townsend Bay. We used these bays because:

  • Areas with contamination due to a known source, like Port Angeles Harbor, cannot be used.  Sampling in another geographic area is allowed under the revised Sediment Management Standards.  (WAC 173-204-560 (5) (d) and (f))
  • These bays are nearby and similar to Port Angeles Harbor. They have a wide range of sediment particle sizes necessary for calculating regional background.
  • These four bays are potentially impacted by many of the same non-point pollution sources as Port Angeles Harbor. Some of the results may be representative of natural background, rather than regional background. If so these results will not be included in regional background calculations (see “Challenges” below). Understanding natural background is necessary for establishing regional background.
  • The bays represent a large enough area to allow us to collect enough samples to compare sediment contaminant concentrations for each of the bays or a combination of bays.

For these reasons we collected sediment samples in Dungeness Bay, Sequim Bay, Discovery Bay, and Port Townsend Bay to develop regional background values for the north Olympic Peninsula.


  • The data distribution and calculated values for Dungeness Bay were similar to and for most chemicals of concern were lower than that for Natural Background. As a result, we removed Dungeness Bay from the regional background data set and recalculated the background values.
  • The second challenge was the carcinogenic Polycyclic Aromatic Hydrocarbons (cPAH) value for the north Olympic Peninsula was low and did not represent the industrial history and population growth of the Harbor. The watersheds of the NOP embayments are less developed and industrialized than Port Angeles Harbor, and their sediments provided regional background concentrations that were disproportionately lower for chemicals assumed to have significant urban contributions. As a result, we decided to calculate a separate Port Angeles cPAH value including Port Angeles Harbor data, given the justification that upland nonpoint PAH sources have often been found to significantly impact sediments in urbanized areas.

Additional Resources

Acronyms used by the Toxic Cleanup Program
Cleanup Process: Major Steps & Definitions

Data Submittal Requirements for All Cleanup Sites

Facility/Site Database

Toxics Cleanup publications

2013 SMS Rule, Chapter 173-204 WAC
2013 SMS Rulemaking
Bellingham Bay Regional Background Study

Page last updated April 11, 2016

Photo: Orca


Final Regional Background report now available  


Clallam & Jefferson counties

Project Manager
Peter Striplin

Public Involvement Coordinator
Megan MacClellan

Repository Locations:

Port Angeles Library
2210 South Peabody Street
Port Angeles, WA 98362

Port Townsend Library
1220 Lawrence Street
Port Townsend, WA 98368
(360) 385-3181

Washington State Department of Ecology
Southwest Regional Office

300 Desmond Drive
Lacey, WA 98516

Please call Susan Baxter at (360) 407-6365 or e-mail for an appointment.