Long-term trends in water quality indicate fecal coliform contamination has decreased but persists at many stations along the Duwamish River
Presentation Abstract
The Duwamish River flows through greater Seattle, WA, and like many urban rivers, has historically been affected by myriad sources of pollution. Improvements to sewage and stormwater conveyance and treatment systems in the last 50 years have led to overall improvements in water quality, but some measures continue to exceed water quality standards. As part of a water quality assessment of the Duwamish River, we are examining current conditions and trends using monitoring data from multiple ambient stations. Water samples have been taken monthly, with measures of some parameters dating back to the early 1990s. Several stations are in areas that receive untreated stormwater and/or discharges of untreated sewage via combined sewer outflows (CSOs), and because of this, we are particularly interested in indicators of untreated water, such as fecal coliform. Although bacteria data are highly variable, long-term trends indicate mean and maximum concentrations of fecal coliform have declined at several stations and are now typically within water quality standards. Water quality improvements may be due in part to the ongoing upgrades of sewer infrastructure (e.g., controls of CSOs). However, evaluating effectiveness of those upgrades is difficult because there are natural as well as anthropogenic sources of fecal coliform, and bacteria counts can be affected by numerous environmental factors including salinity, which is dynamic in the tidally-influenced lower section of the river. High fecal coliform counts at stations upstream of CSOs indicate there are likely many sources contributing fecal coliform contamination throughout the river.
Session Title
Session S-04B: Water Quality I
Conference Track
Toxics
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
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Enterobacteriacease--Washington (State)--Duwamish River; Sewage--Environmental aspects--Washington (State)--Duwamish River; Water--Pollution--Washington (State)--Duwamish River
Geographic Coverage
Salish Sea (B.C. and Wash.); Duwamish River (Wash.)
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
Long-term trends in water quality indicate fecal coliform contamination has decreased but persists at many stations along the Duwamish River
Room 6C
The Duwamish River flows through greater Seattle, WA, and like many urban rivers, has historically been affected by myriad sources of pollution. Improvements to sewage and stormwater conveyance and treatment systems in the last 50 years have led to overall improvements in water quality, but some measures continue to exceed water quality standards. As part of a water quality assessment of the Duwamish River, we are examining current conditions and trends using monitoring data from multiple ambient stations. Water samples have been taken monthly, with measures of some parameters dating back to the early 1990s. Several stations are in areas that receive untreated stormwater and/or discharges of untreated sewage via combined sewer outflows (CSOs), and because of this, we are particularly interested in indicators of untreated water, such as fecal coliform. Although bacteria data are highly variable, long-term trends indicate mean and maximum concentrations of fecal coliform have declined at several stations and are now typically within water quality standards. Water quality improvements may be due in part to the ongoing upgrades of sewer infrastructure (e.g., controls of CSOs). However, evaluating effectiveness of those upgrades is difficult because there are natural as well as anthropogenic sources of fecal coliform, and bacteria counts can be affected by numerous environmental factors including salinity, which is dynamic in the tidally-influenced lower section of the river. High fecal coliform counts at stations upstream of CSOs indicate there are likely many sources contributing fecal coliform contamination throughout the river.
