Publication Summary

From 1997-1999, sediments were collected throughout Puget Sound as part of a joint monitoring program conducted by the Washington State Department of Ecology and the National Oceanic and Atmospheric Administration. Analyses were performed to quantify concentrations of potentially toxic chemicals, responses in laboratory toxicity tests, and the structure of benthic infauna communities in sediments. Degraded sediment conditions occurred in samples that represented about 1%, high quality in about 68%, and intermediate conditions in about 31% of the total study area. Quality is also compared between six Puget Sound regions, and to estuaries nationwide. Relative to many other estuaries and marine bays along the U.S. coastline, Puget Sound sediments were ranked among the least contaminated and toxic.

From 1997-1999, surficial sediments were collected from 300 randomly chosen locations throughout Puget Sound as part of a joint monitoring program conducted by the Washington State Department of Ecology and the National Oceanic and Atmospheric Administration. The study was designed to provide information on the severity, spatial patterns, and spatial extent of contamination, toxicity, and degraded benthos and to identify the relationships among these measures of sediment quality. Analyses were performed to quantify concentrations of numerous potentially toxic chemicals, responses in laboratory toxicity tests, and the structure of benthic infauna communities in sediments. Results for the 2363 km2 survey area are summarized in this report.

Degraded conditions, as indicated with a combination of relative high chemical concentrations, statistically significant responses in one or more tests of toxicity, and adversely altered benthos, occurred in samples that represented about 1% of the total area. These conditions invariably occurred in samples collected within urbanized bays and industrial waterways, especially near the urban centers of Everett, Seattle, Tacoma, and Bremerton, where degraded conditions had been reported in previous studies. Sediments with high quality (as indicated by no elevated chemical concentrations, no significant responses in the toxicity tests, and the presence of abundant and diverse infauna and or pollution sensitive taxa) occurred in samples that represented a majority, 68%, of the total study area. Sediments in which results of the three kinds of analyses were not in agreement were classified as intermediate in quality and represented about 31% of the total area. This relatively large area with intermediate sediment quality is suggested as in most need of continued surveillance because of the heterogeneity and transitional nature of the sediments.

Sediment quality is also compared between six Puget Sound regions, and to estuaries nationwide. Relative to many other estuaries and marine bays along the U.S. coastline, Puget Sound sediments were ranked among the least contaminated and toxic.