Puget Sound Marine Sediment Baseline

Surface sediments from 381 stations were surveyed throughout the greater Puget Sound/southern Salish Sea area between 1997 and 2003. Data were summarized using Ecology's Sediment Quality Triad Index for a Sound-wide baseline characterization of the spatial extent, or area, of sediment quality on a 5-level scale from unimpacted to clearly impacted.

Findings 1997-2003

  • Unimpacted sediment conditions, as indicated by no contamination, no toxicity, and the presence of abundant and diverse benthic organisms, occurred in samples that represented 65% of the study area.
  • Sediments were likely unimpacted in 30% of the study area. That is, there were no strong indications of chemical contamination, toxicity, or biological effects. Continued surveillance of these areas is suggested because of their roles as critical habitat for numerous marine organisms.
  • Possibly, likely, or clearly impacted conditions were measured in about 3% of the study area depending on the combination and severity of contamination, toxicity, and/or biological effects. These conditions invariably occurred in samples collected in urbanized bays and industrial waterways, especially near Everett, Seattle, Tacoma, and Bremerton, where degraded conditions had been reported in previous studies.
  • In a few samples, representing 1% of the study area, the triad indications were inconclusive.

Relative to many other estuaries and marine bays along the U.S. coastline, Puget Sound sediments were ranked among the least contaminated and toxic.

2004-2014 Update

The entire Puget Sound sediment sampling frame is being resampled, region by region, between 2004 and 2014. Sound-wide sediment quality data generated during this period will be compared to the original (1997-2003) baseline data to determine changes in sediment quality over time. An update of the sound-wide Sediment Quality Triad Index calculations will be posted in 2015.


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.