Central Sound Marine Sediments Data Summaries, Findings, Publications

Central Sound

The following table contains links to data summaries. (Click on X to open files. Zip files will need to be extracted into another folder. Shaded boxes indicate summaries not yet available.)

Year Sampled Station Locations Physical Chemical Toxicity Benthic Invertebrates Sediment Quality Triad Indicators
1998-1999 * * * * * *
2008-2009 X X X X X X

* Available upon request.


The Central Sound Sediment Quality Triad Index (PDF) offers a one-page summary of these findings.

Puget Sound Marine Sediment Indicators is a webpage that describes the Sediment Quality Triad Index, a method to rate the health of marine sediments.


Findings 2008-2009

All our studies assess sediment quality by evaluating chemistry, toxicity, and benthic (sediment-dwelling) invertebrate community structure. Results are compared with those from similar surveys, conducted with the same methods, to determine changes in sediment quality.

  • Overall sediment quality in Central Sound declined over this 10-year period, and significant changes (both positive and negative) in several individual parameters and indices were detected.
    • Concentrations of lead, mercury, silver, and tin decreased significantly.
    • Concentrations of some polycyclic aromatic hydrocarbons (PAHs) decreased significantly; concentrations of other PAHs remained unchanged.
    • Toxicity increased in severity and spatial extent.
    • Increase in adversely affected benthic invertebrate communities.

Results are rolled up into the Sediment Quality Triad Index, which categorizes sediment quality on a 5-level scale from unimpacted to clearly impacted.  The triad index combines information on measures of exposure (sediment contamination), response (toxicity), and biological effects (benthic invertebrates).

  • Decrease in unimpacted sediment quality and increase in likely impacted sediment quality.


Partridge, V., S. Weakland, Dutch, M., E. Long, and K. Welch. 2013. Sediment Quality in Central Puget Sound, Changes over a 10-Year Period. Washington State Department of Ecology Publication 13-03-021.

Quality Assurance Project Plan

Dutch, M., V. Partridge, S. Weakland, K. Welch, and E. Long. 2009. Quality Assurance Project Plan: The Puget Sound Assessment and Monitoring Program Sediment Monitoring Component. Washington State Department of Ecology Publication 09-03-121. 98 pp.