Skip to main content
U.S. flag

An official website of the United States government

Here’s how you know

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

HTTPS

Secure .gov websites use HTTPS
A lock (LockA locked padlock) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

    • Environmental Topics
    • Air
    • Bed Bugs
    • Cancer
    • Chemicals, Toxics, and Pesticide
    • Emergency Response
    • Environmental Information by Location
    • Health
    • Land, Waste, and Cleanup
    • Lead
    • Mold
    • Radon
    • Research
    • Science Topics
    • Water Topics
    • A-Z Topic Index
    • Laws & Regulations
    • By Business Sector
    • By Topic
    • Compliance
    • Enforcement
    • Laws and Executive Orders
    • Regulations
    • Report a Violation
    • Environmental Violations
    • Fraud, Waste or Abuse
    • About EPA
    • Our Mission and What We Do
    • Headquarters Offices
    • Regional Offices
    • Labs and Research Centers
    • Planning, Budget, and Results
    • Organization Chart
    • EPA History

Breadcrumb

  1. Home
  2. Salish Sea

Listing of Contaminant Studies in the Salish Sea

The tables below include a listing of some of the scientific contaminant studies conducted in the Salish Sea.

  • Long-term monitoring studies use consistent methods to look at the same contaminants over time, measuring for changes in concentrations.
  • Contaminant-focused monitoring studies, or focal studies, collect information over a shorter period of time, to investigate more specific questions such as differences in contaminant levels associated with various land uses (e.g. urban, industrial, or forested areas). 

Salish Sea Long-term Contaminant Monitoring Studies
Contaminant Area Species Sample Type Period Reported Trend Author(s)
Metals Salish Sea Bivalve mollusks Soft tissue 1986-2007 Decline overall (a few urban sites of concern). Kimbrough, et al. (2008)
Metals Georgia Basin Freshwater fishes Tissue 2004-2012 No overall trends detected. ENKON (2012)
Metals Georgia Basin Peamouth chub Muscle; whole body samples 2004-2012 Stable ENKON (2012)
Metals Puget Sound Native mussels Tissue 2015-2018 Highest concentrations in urban bays. Langness, et al. (2020)
PCBs Salish Sea Harbor seal Blubber 1983-2003 Decline Ross, et al. (2013)
PCBs Salish Sea Bivalve molluscs Soft tissue 1986-2007 Decline Kimbrough, et al. (2008)
PCBs Puget Sound Pacific herring Whole-body samples 1994-2014 Decline (in a low-development basin), high concentrations and stable  (in an urbanized basin). West, et al. (2017)
PCBs Puget Sound English sole Skin-off muscle samples 1997-2015 Stable (in many basins; increasing in some). West, et al. (2017)
PCBs Georgia Basin River otters Scat 1998-2010 Decline Huang, et al. (2018)
PCBs Georgia Basin Peamouth chub Muscle, whole-body samples 2004-2012 Decline ENKON (2012)
PCBs Georgia Basin Largescale sucker Whole-body samples 2007-2013 Decline ENKON (2012)
PCBs Puget Sound Native mussels Soft tissue 2015-2018 Higher median concentrations over study. Langness, et al. (2020)
PBDEs Salish Sea Double-crested cormorant Eggs 1979-2012 Increase to to peak in 1994, then decrease after 2000. Elliott, et al. (2005)
Miller, et al. (2015a)
PBDEs Salish Sea Great blue heron Eggs 1983-2012 Increase to peak in 1994, then decrease. Elliott, et al. (2005)
Miller, et al. (2015a)
PBDEs Salish Sea Harbor seal Blubber 1983-2003 Decline Ross, et al. (2013)
PBDEs Puget Sound Pacific herring Whole-body samples 1994-2014 Decline West, et al. (2017)
PBDEs Puget Sound Bivalve molluscs Soft tissue 1996-2007 Stable overall. Kimbrough, et al. (2009)
PBDEs Puget Sound English sole Skin-off muscle samples 1997-2015 Decline overall. West, et al. (2017)
PBDEs Georgia Basin Peamouth chub Muscle, whole-body samples 2004-2012 Stable ENKON (2012)
PBDEs Georgia Basin Largescale sucker Whole-body samples 2007-2013 Stable ENKON (2012)
PBDEs Puget Sound Native mussels Soft tissue 2015-2018 Slightly lower over time. Langness, et al. (2020)
DDT Salish Sea Bivalve molluscs Soft tissue 1986-2009 Decline Kimbrough, et al. (2008)
Sericano, et al. (2014)
DDT Puget Sound Pacific herring Whole-body samples 1994-2014 Decline West, et al. (2017)
DDT Puget Sound English sole Skin-off muscle samples 1997-2015 Decline overall. West, et al. (2017)
DDT Georgia Basin Peamouth chub Muscle, whole-body samples 2004-2012 Stable ENKON (2012)
DDT Georgia Basin Largescale sucker Whole-body samples 2007-2013 Stable ENKON (2012)
DDT Puget Sound Native mussels Soft tissue 2015-2018 Higher median concentrations over study. Langness, et al. (2020)
PAHs Salish Sea Bivalve molluscs Soft tissue 1986-2007 Decline Kimbrough, et al. (2008)
PAHs Georgia Basin Peamouth chub Muscle 2007-2012 Detected during final phase of study. ENKON (2012)
PAHs Salish Sea Orca Scat 2010-2013 No trend; considered baseline data. Lundin, et al. (2018)
PAHs Puget Sound Native mussels Soft tissue 2015-2018 Slightly higher over time. Langness, et al. (2020)
Other (PCDEs, PCNs) Salish Sea Harbor seal Blubber 1983-2003 Decline Ross, et al. (2013)
Other (pesticides) Salish Sea Bivalve molluscs Soft tissue 1986-2007 Decline Kimbrough, et al. (2008)
Other (dioxins/furans) Georgia Basin Peamouth chub Muscle, whole-body samples 2004-2012 Decline in some areas. ENKON (2012)
Other (PFAS) Salish Sea Aquatic birds Egg 1990-2011 Species differences in concentrations;
higher concentrations in urban areas.
Miller, et al. (2015b)

Salish Sea Contaminant-focused Monitoring Studies
Contaminant Area Species Sample Type Period Finding Author(s)
Metals Georgia Basin English sole Muscle; whole body samples 2007 Some metal concentrations elevated at sites. Nautilis (2009)
Metals Puget Sound Chinook salmon Composite tissues 2013 Metals exposure varies greatly among locations. O'Neill, et al (2015)
Metals Puget Sound Harbor seals Liver 2009-2012 Age-related effects; regional differences. Ashley, et al. (2020)
Metals Georgia Basin Pacific herring Muscle 2016 Different lead uptake than in other parts of B.C. Li, et al. (2020)
PCBs Georgia Basin English sole Muscle, whole-body samples 2007 Variation among sites. Nautilis (2009)
PCBs Georgia Basin Stellar's sea lions Blubber 2005-2006 Confirmed biomagnification between life stages. Alava, et al. (2012)
PCBs Georgia Basin Plankton Whole-body samples 2005-2006 Seasonal differences in uptake. Frouin, et al. (2013)
PCBs Puget Sound Chinook salmon Composite tissues 2013 PCB concentrations elevated in more developed areas. O'Neill, et al. (2015)
PCBs Salish Sea Orca Blubber, scat 2010-2013 Decline in concentration as Chinook salmon prey abundance increased. Lundlin, et al. (2016)
PCBs Puget Sound Steelhead smolts Gutted whole-body samples 2014 PCB concentrations rose with smolt length. Chen, et al. (2018)
PCBs Puget Sound Chinook salmon Gutted whole-body samples 2016 Differences between hatchery-origin and wild fish, differences among collection sites. O'Neill, et al. (2020)
PBDEs Georgia Basin English sole Muscle, whole-body samples 2007 Spatial pattern with elevated concentrations at one site. Nautilis (2009)
PBDEs Georgia Basin Stellar's sea lions Blubber 2005-2006 Confirmed biomagnification between life stages. Alava, et al. (2012)
PBDEs Georgia Basin Plankton Whole-body samples 2005-2006 Seasonal differences in uptake. Frouin, et al. (2013)
PBDEs Puget Sound Chinook salmon Composite tissue 2013 PBDEs elevated in a few locations. O'Neill, et al. (2015)
PBDEs Salish Sea Orca Blubber, scat 2010-2013 Decline in concentration as Chinook salmon prey abundance increased. Lundlin, et al. (2016)
PBDEs Puget Sound Steelhead smolts Gutted whole-body samples 2014 PBDE concentrations showed relationship to location, not smolt length. Chen, et al. (2018)
PBDEs Puget Sound Chinook salmon Gutted whole-body samples 2016 Differences between hatchery-origin and wild fish, differences among collection sites with PBDEs elevated in wild fish near waste water treatment discharges. O'Neill, et al. (2020)
DDT Georgia Basin English sole Muscle, whole-body samples 2007 Some concentrations elevated at sites, decreased compared to historic studies. Nautilis (2009)
DDT Puget Sound Chinook salmon Composite tissue 2013 DDT concentrations quite low with slight elevation in more developed areas. O'Neill, et al. (2015)
DDT Salish Sea Orca Blubber, scat 2010-2013 Decline in concentration as Chinook salmon prey abundance increased. Lundlin, et al. (2016)
DDT Puget Sound Steelhead smolts Gutted whole-body samples 2014 DDT concentrations rose with smolt length. Chen, et al. (2018)
DDT Puget Sound Chinook salmon Gutted whole-body samples 2016 Concentrations related to fish size and origin. O'Neill, et al. (2020)
PAHs Georgia Basin English sole Muscle, whole-body samples 2007 Low concentrations detected. Nautilis (2009)
PAHs Puget Sound Chinook salmon Composite tissue 2013 PAHs elevated in more developed areas. O'Neill, et al. (2015)
PAHs Puget Sound Butter clams Homogenized tissue No date Variability at different beaches but related to concentrations detected for site pore water. Minick, et al. (2019)
PAHs Puget Sound Pacific herring Embryos 2013-2015 Embryos incubating near sources have increased concentrations.  West, et al. (2019)
Microplastics Georgia Basin Manila clams Soft tissue No date No difference in counts between aquaculture sites and non-aquaculture sites. Davidson and Dudas (2016)
Microplastics Georgia Basin Chinook salmon juveniles Stomach contents 2015 No relationship between microplastic content of fish and the ambient concentration in water. Collicutt, et al. (2019)
Microplastics Salish Sea Pacific sand lance Stomach contents 2015-2016 No fibers in first study year but they were present in the second. Hipfner, et al. (2018)
Microplastics Salish Sea Pacific herring Stomach contents 2015-2016 No fibers in first study year but they were present in the second. Hipfner, et al. (2018)
Microplastics Georgia Basin Pacific oysters Soft tissue 2016 No difference in counts between aquaculture sites and non-aquaculture sites. Covernton, et al. (2019)
Microplastics Salish Sea Pacific oysters Soft tissue 2018 While low amounts of microplastics were found, the polymer sources were highly variable. Martinelli, et al. (2020)
Other (dioxins/furans) Georgia Basin English sole Muscle, whole-body samples 2007 Spatial pattern with elevated concentrations on eastern sites. Nautilis (2009)
Other (150 CECs) Puget Sound Chinook salmon juveniles Whole-body samples 2014 CECs in juvenile Chinook salmon detected at a greater frequency and higher concentrations than staghorn sculpin. Meador, et al. (2016)
Other (150 CECs) Puget Sound Staghorn sculpins Whole-body samples 2014 Comparison between 2 effluent sites showed similar concentrations and frequencies of occurrence for detected CECs. Meador, et al. (2016)
Other (pharmaceuticals, personal care products) Georgia Basin Horse mussel Soft tissue 2015 Concentrations declined with distance from municipal wastewater effluent diffuser. Krogh, et al. (2017)
Other (pharmaceuticals, personal care products) Georgia Basin Benthic biota Homogenized samples 2015 2 samples of 60 each had measurable concentrations of one of 12 analytes; most compounds not detected. Krogh, et al. (2017)
Other (alkylphenols, pharmaceuticals, PFOSA, pesticides) Salish Sea Bay mussels Composite site samples 2012-2013 Confirmed exposure to a wide range of emerging contaminants, at low concentrations. James, et al. (2020) 

Salish Sea

  • Executive summary
  • About this report
  • Air quality
  • Chinook salmon
  • Freshwater quality
  • Marine species at risk
  • Marine water quality
  • Shellfish beaches
  • Southern Resident Killer Whales
  • Stream flow
  • Swimming beaches
  • Toxics in the food web
  • Acknowledgements
Contact us about the Health of the Salish Sea Report
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on February 21, 2025
  • Assistance
  • Spanish
  • Arabic
  • Chinese (simplified)
  • Chinese (traditional)
  • French
  • Haitian Creole
  • Korean
  • Portuguese
  • Russian
  • Tagalog
  • Vietnamese
United States Environmental Protection Agency

Discover.

  • Accessibility Statement
  • Budget & Performance
  • Contracting
  • EPA www Web Snapshot
  • Grants
  • No FEAR Act Data
  • Plain Writing
  • Privacy
  • Privacy and Security Notice

Connect.

  • Data
  • Inspector General
  • Jobs
  • Newsroom
  • Regulations.gov
  • Subscribe
  • USA.gov
  • White House

Ask.

  • Contact EPA
  • EPA Disclaimers
  • Hotlines
  • FOIA Requests
  • Frequent Questions
  • Site Feedback

Follow.