Abstract Title

Session S-01B: PCBs in the Green/Duwamish Watershed

Proposed Abstract Title

Evaluation of PCB Congeners in Surface Waters from the Green River and its Major Tributaries

Keywords

Toxics

Location

Room 608-609

Start Date

30-4-2014 10:30 AM

End Date

30-4-2014 12:00 PM

Description

The Green River Basin is a source of PCBs to the Lower Duwamish Waterway (LDW) Superfund Site. Therefore, King County conducted a water quality assessment to examine relative differences of PCB concentrations in the Green River and four of its major tributaries. The study was designed to address the following questions: 1) How do the relative contributions of key contaminants differ between baseflow and storm event conditions? 2) What are the relative spatial differences in key contaminants in the Green River and its major tributaries? In 2011 and 2012, surface water samples were collected from four major tributaries to the Green River, as well as two main stem Green River locations: an upstream location at Flaming Geyser State Park, and a downstream location at Foster Links Golf Course. At each of the six locations, three composite baseflow and six composite storm event samples were collected. All samples were analyzed for arsenic, PAHs, PCB congeners and conventional parameters; however this presentation will focus only on PCB results. In most samples, PCB concentrations were higher during storm events than under baseflow conditions. PCB concentrations during storm events tended to be higher at the three most downstream locations. Under baseflow conditions, PCB concentrations were similar across the tributary basins and the main stem locations with the exception of one sample collected from Soos Creek. Additional data from sampling stations further upstream on the Green River, including above the Howard Hanson Dam were collected in 2013; these data will also be presented. Data from this study will be used as a line of evidence to evaluate upstream contaminant sources to the LDW, improve the understanding and nature of these inputs (e.g., influence of storm events), and inform future source control efforts in the watershed.

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Apr 30th, 10:30 AM Apr 30th, 12:00 PM

Evaluation of PCB Congeners in Surface Waters from the Green River and its Major Tributaries

Room 608-609

The Green River Basin is a source of PCBs to the Lower Duwamish Waterway (LDW) Superfund Site. Therefore, King County conducted a water quality assessment to examine relative differences of PCB concentrations in the Green River and four of its major tributaries. The study was designed to address the following questions: 1) How do the relative contributions of key contaminants differ between baseflow and storm event conditions? 2) What are the relative spatial differences in key contaminants in the Green River and its major tributaries? In 2011 and 2012, surface water samples were collected from four major tributaries to the Green River, as well as two main stem Green River locations: an upstream location at Flaming Geyser State Park, and a downstream location at Foster Links Golf Course. At each of the six locations, three composite baseflow and six composite storm event samples were collected. All samples were analyzed for arsenic, PAHs, PCB congeners and conventional parameters; however this presentation will focus only on PCB results. In most samples, PCB concentrations were higher during storm events than under baseflow conditions. PCB concentrations during storm events tended to be higher at the three most downstream locations. Under baseflow conditions, PCB concentrations were similar across the tributary basins and the main stem locations with the exception of one sample collected from Soos Creek. Additional data from sampling stations further upstream on the Green River, including above the Howard Hanson Dam were collected in 2013; these data will also be presented. Data from this study will be used as a line of evidence to evaluate upstream contaminant sources to the LDW, improve the understanding and nature of these inputs (e.g., influence of storm events), and inform future source control efforts in the watershed.