Event Title

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

Presentation Abstract

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.

Session Title

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

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Location

Room 6C

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

This document is currently not available here.

Share

COinS
 
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.