Abstract Title

Session S-04B: Water Quality I

Presenter/Author Information

Kate MacNealeFollow

Keywords

Toxics

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

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.

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

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.