Publication Summary

This is the study plan for tracking short-term movements of suspended sediments in the Lower Duwamish Waterway.

A recent sediment transport model predicts that nearly all the yearly sediment load entering the Lower Duwamish Waterway (LDW) comes from the Green River. About one-half is predicted to be deposited within the LDW. However, the accumulation of sediment and sediment-associated contaminants differs by reach, water depth, settling velocity, and other factors.

This 2009 study will use artificial sediment particles with a "dual-signature" (fluorescent and magnetic) to identify short-term sediment transport pathways and patterns of sediment accumulation. The tracer particles, manufactured to mimic native sediments, will be released into the LDW and later recovered from the water column and surface sediments.

The mass and particle size distribution of the tracer particles recovered from various locations in the LDW will be described and can be compared to model predictions. Results may also be used to make inferences about patterns of transport and areas accumulating contaminants associated with incoming suspended sediments.

Each study conducted by the Washington State Department of Ecology must have an approved Quality Assurance Project Plan. The plan describes the objectives of the study and the procedures to be followed to achieve those objectives. After completion of the study, a final report describing the study results will be posted to the Internet.