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Urban Waters Initiative
Marine Sediment Monitoring for Ecology's Urban Waters Initiative
Elliott Bay/Lower Duwamish and Commencement Bay
Environmental Management Application
As part of Ecology's
Urban Waters Initiative,
the Environmental Assessment Program (EAP) is conducting baseline and 5-year follow-up monitoring
of sediments in
Elliott Bay
(including the adjoining waterways of the lower Duwamish River) and
Commencement Bay. EAP's sediment monitoring team will assess
sediment quality and provide environmental managers with information on the
bay-wide extent of sediment contamination, changes in sediment quality over time, and the long-term effectiveness of the collective toxics management efforts in these urban bays.
Background
Through the Urban Waters Initiative, Ecology’s Toxic Cleanup, Hazardous Waste, and Water Quality Programs have aligned their source control and cleanup efforts in
Elliott Bay/lower Duwamish and Commencement Bay to reduce toxic chemical pollution from stormwater
runoff and other sources. These actions are meant to reduce
toxics entering the bays and prevent re-contamination of
sediments at sites that have been cleaned up or are in the
process of being cleaned up.
Sediment Monitoring Goals and Objectives
Sediment quality data are being collected and analyzed to:
- Provide a baseline: Provide a current “bay-scale” baseline sediment quality assessment prior to Ecology’s Urban Waters Initiative source control and cleanup activities.
- Compare to the past:: Compare the current bay-scale
sediment quality assessment with past data to determine whether sediment
conditions have changed in the past 10 years. In other words, has
sediment quality throughout the bay improved, deteriorated, or stayed the
same?
- Monitor Effectiveness: Evaluate the effectiveness of collective source control and cleanup actions in each embayment
at 5-year monitoring intervals on an ongoing basis. Effectiveness monitoring data can be used as performance measures in adaptive management strategies developed for Puget Sound.
- Provide perspective: Compare and relate site-specific sediment quality data to that of the whole bay,
and compare bay-scale sediment quality to the larger-scale regional and Puget Sound-wide sediment quality
assessed as part of the Puget Sound Assessment and Monitoring Program (PSAMP).
Sampling Design
The embayment-scale sediment monitoring surveys conducted for the Urban Waters Initiative were “nested” within the
larger-scale regional
sediment monitoring surveys designed for PSAMP.
Study areas were defined for both Elliott Bay/lower Duwamish (2007) and Commencement Bay (2008) within the
PSAMP Central Puget Sound Region. Sample sites were
selected using a probability-based random stratified sampling design.
Thirty random stations in each bay previously sampled for the
PSAMP/NOAA partnership in 1998 and 1999 were chosen for sampling. Sampling in these two embayments will be repeated at 5-year intervals to recharacterize
the sediments and assess changes over time.
Sediment quality indicators measured include sediment chemistry (metals, PAHs, PCBs, pesticides, and other organic contaminants), toxicity, and sediment-dwelling invertebrate communities (benthos). The results are combined into the Sediment Quality Triad Index (SQTI) to depict sediment quality on a scale from high to degraded.
Ecology has now expanded this monitoring program to include the Bainbridge Basin (Sinclair and Dyes Inlets, sampled in 2009), Bellingham Bay (2010),
Budd Inlet (2011), and Everett Harbor/Port Gardner (2012).
Analysis
Sediment baseline data have been generated for Elliott Bay
and Commencement Bay, and analyzed to determine the incidence
(number and % of stations) and spatial extent (amount and % of
area) of chemical contamination, toxicity, and affected benthos within each embayment. These values
are being compared with those in the larger region and Puget Sound-wide. Statistical comparisons of sediment
conditions between years are being conducted to provide evidence of change in measured parameters over time, i.e., “Are levels of contaminants, toxicity,
and indicators of benthic community health increasing, decreasing, or remaining unchanged within the embayment?”
Findings
Elliott Bay and adjoining waterways
Analyses of the 2007 sediment monitoring data from Elliott
Bay have been completed and are contained in a
new Ecology
Report. A
four-page summary of the report and a
focus
sheet summarizing the changes are also available.
Commencement Bay
Analyses of the 2008 sediment monitoring data from Commencement Bay are in progress. Preliminary results suggest that most, but not all, of the sediment quality indicators measured showed improvements in sediment quality bay-wide between 1999 and 2008. Specifically:
Summaries of other studies of chemical contamination in Elliott Bay/lower Duwamish,
and Commencement Bay
Chemical concentration data from sediment, water, and tissue
samples collected from Elliott and Commencement Bays were downloaded from
Ecology’s Environmental Information Management System (EIM) and compiled into a GIS-linked Urban Waters Initiative database. Other summarized results were compiled from various local, state, and national natural resource agency publications, as well as from peer reviewed journals.
These sediment data were examined, summarized, compared to Washington State Sediment Quality Standards and Puget Sound average ambient values, and displayed on spatial distribution maps. Summaries of the chemical concentrations in biota taken from the literature are also listed.
Elliott Bay/lower Duwamish
Commencement Bay
Urban Waters Database
Data
Raw data can be obtained by downloading the compressed Microsoft Access
sediment monitoring database, or by contacting Sandra
Weakland
sgei461@ecy.wa.gov.
