Whidbey Basin Marine Sediment Data Summaries, Findings, Publications

Whidbey Basin

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
1997 * * * * * *
2007 X X X X X X

*Available upon request.


The Whidbey Island 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 2007

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.

  • In 2007 concentrations of two chemicals (hexachlorobenzene, dibenzofuran) at two stations exceeded the Washington Sediment Quality Standards (SQS), indicating that organisms living in these sediments could be harmed. Those two stations together represented 2.4% of the total area of the region.
  • The proportion of area exceeding SQS decreased from 9.1% (1997) to 2.4% (2007).
  • Two samples in 2007 had toxic responses in the sea urchin fertilization toxicity tests. The “toxic” samples were from Everett Harbor and Saratoga Passage and represented 3.3 % of the study area.
  • The amount of area with toxic sediments decreased from 6% (1997) to 3.3% in (2007).
  • Fifty-three percent of the study area in 2007 had adversely affected benthos.
  • The amount of area with adversely affected benthic invertebrate communities also decreased, from 69% (1997) to 53% (2007).

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).

  • The majority of the area (94.4%) in 2007 had unimpacted or likely unimpacted sediment quality.
  • No samples in 2007 had clearly impacted sediment quality.
  • The proportion of area with unimpacted or likely unimpacted sediment quality remained unchanged from 1997 to 2007.



Partridge, V., S. Weakland, M. Dutch, E. Long, and K. Welch. 2013. Sediment Quality in the Whidbey Basin, Changes from 1997 to 2007. Washington State Department of Ecology Publication 13-03-003. 8 pp.

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.