Abstract Title

Session S-10D: Cross-Habitat Linkages and Landscape Scale Approaches to Ecosystem Management

Proposed Abstract Title

Influence of the Duwamish River on water quality in Elliott Bay, Seattle, WA

Presenter/Author Information

Wendy Eash-LoucksFollow

Keywords

Species and Food Webs

Location

Room 6C

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

Elliott Bay, an urbanized bay surrounded by the city of Seattle, WA within the Puget Sound Central Basin, receives its greatest influx of fresh water from the Lower Duwamish River, located in the southeast corner of the bay. As the river enters the bay, the net flow is counterclockwise along the Seattle waterfront. The Lower Duwamish Waterway (LDW), which extends from the Upper Turning Basin downstream to the tip of Harbor Island, has been extensively modified over the past 100 years. The LDW is highly industrialized, receives heavy vessel traffic, and contains numerous combined sewer overflow and stormwater outfalls. River discharge can have a substantial impact on water quality in Elliott Bay, particularly physical parameters such as temperature, salinity, and turbidity. Water quality parameters were examined both spatially and temporally to determine influences of the Duwamish River on Elliott Bay water quality. Sampling has occurred in Elliott Bay for more than 30 years, and the Duwamish River influence can be seen in the seasonally-variable freshwater lens captured in monthly samples. Continuous monitoring at a mooring station installed in 2008 on the Seattle waterfront has demonstrated the correlation between river discharge and surface salinity as well as turbidity. Surface bacteria concentrations at ambient monitoring sites near the Seattle waterfront are significantly higher than those at ambient and outfall stations throughout the bay, indicating that the river has a large impact on both physical and biological conditions in Elliott Bay, particularly along the Seattle waterfront. Both the Duwamish River and Elliott Bay are listed as impaired waters for bacteria, dissolved oxygen, chemical contaminants, and ammonia on Ecology’s 303(d) list; therefore, it is essential to understand the linkage between the freshwater and marine systems in order to determine physical, chemical, and biological effects of the linkage as well as sources and fates of contaminants.

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May 1st, 5:00 PM May 1st, 6:30 PM

Influence of the Duwamish River on water quality in Elliott Bay, Seattle, WA

Room 6C

Elliott Bay, an urbanized bay surrounded by the city of Seattle, WA within the Puget Sound Central Basin, receives its greatest influx of fresh water from the Lower Duwamish River, located in the southeast corner of the bay. As the river enters the bay, the net flow is counterclockwise along the Seattle waterfront. The Lower Duwamish Waterway (LDW), which extends from the Upper Turning Basin downstream to the tip of Harbor Island, has been extensively modified over the past 100 years. The LDW is highly industrialized, receives heavy vessel traffic, and contains numerous combined sewer overflow and stormwater outfalls. River discharge can have a substantial impact on water quality in Elliott Bay, particularly physical parameters such as temperature, salinity, and turbidity. Water quality parameters were examined both spatially and temporally to determine influences of the Duwamish River on Elliott Bay water quality. Sampling has occurred in Elliott Bay for more than 30 years, and the Duwamish River influence can be seen in the seasonally-variable freshwater lens captured in monthly samples. Continuous monitoring at a mooring station installed in 2008 on the Seattle waterfront has demonstrated the correlation between river discharge and surface salinity as well as turbidity. Surface bacteria concentrations at ambient monitoring sites near the Seattle waterfront are significantly higher than those at ambient and outfall stations throughout the bay, indicating that the river has a large impact on both physical and biological conditions in Elliott Bay, particularly along the Seattle waterfront. Both the Duwamish River and Elliott Bay are listed as impaired waters for bacteria, dissolved oxygen, chemical contaminants, and ammonia on Ecology’s 303(d) list; therefore, it is essential to understand the linkage between the freshwater and marine systems in order to determine physical, chemical, and biological effects of the linkage as well as sources and fates of contaminants.