Publication Summary

In November 1988 the Washington State Department of Ecology began a Sediment Trap Monitoring Program in the Nearshore/Tideflats area of Commencement Bay. The program was aimed at evaluating the effectiveness of source control efforts designed to reduce the input of problem chemicals to Thea Foss Waterway. The primary component of this program consisted of a quarterly collection of settling particulate matter (SPM) with the use of moored sediment traps. In-place bottom sediments, current velocity measurements and water column profile data have also been collected periodically as part of the program. Based on the results from Thea Foss Waterway, sediment trap monitoring was expanded in July 1990 to include Hylebos and Sitcum Waterways.

In November 1988 the Washington State Department of Ecology began a Sediment Trap Monitoring Program in the Nearshore/Tideflats area of Commencement Bay. The program was aimed at evaluating the effectiveness of source control efforts designed to reduce the input of problem chemicals to Thea Foss Waterway. The primary component of this program consisted of a quarterly collection of settling particulate matter (SPM) with the use of moored sediment traps. In-place bottom sediments, current velocity measurements and water column profile data have also been collected periodically as part of the program. Based on the results from Thea Foss Waterway, sediment trap monitoring was expanded in July 1990 to include Hylebos and Sitcum Waterways.

This report presents an update of SPM and bottom sediment monitoring data collected from Hylebos, Sitcum and Thea Foss Waterways between June 1991 and June 1995. Information on the distribution of contaminants, trends in contaminant levels, estimated sedimentation and bottom sediment resuspension rates, and comparisons with the Commencement Bay "Sediment Quality Objectives" is discussed. Recommendations for follow-up work are also presented.

Link to EIM data for User Study ID DNOR0005