Publication Summary

During the spring of 2007, the Department of Ecology (Ecology) conducted toxics monitoring from 14 City of Spokane storm drains discharging to the Spokane River. Ecology measured polybrominated diphenylether flame retardants (PBDEs) in stormwater as well as dioxins/furans, total organic carbon, and grain size in sediments from stormwater manholes.

The concentrations of both PBDEs and dioxin/furans appear to be typical for urban areas in Washington State, based on the little data available for comparisons. These 2007 data will be used by Ecology′s Urban Waters Initiative for further source tracing efforts.

Historically, concentrations of polybrominated diphenylether flame retardants (PBDEs) and dioxins in fish from the Spokane River have been elevated. These high levels spurred sampling during 2007 of water and sediment from 14 City of Spokane storm drains discharging directly to the river.

Stormwater samples from manholes were collected during 3 storm events and measured for PBDEs. In addition, 7 sediment samples were collected during a dry period and measured for dioxin/furans, total organic carbon (TOC), and grain size. These samples were collected opportunistically, alongside other samples taken for the Spokane River PCB TMDL Stormwater Loading Analysis by Parsons and Terragraphics.

PBDEs were detected in 7 of 14 stormwater samples, with concentrations ranging from 0.002 to 0.023 ug/L. Dioxin/furans were detected in 7 of 14 sediment samples with concentrations ranging from 0.065 to 17.7 ng/Kg TEQ.

The data collected will be used to help prioritize storm-drain systems for further source -tracking efforts.

Link to EIM data for User Study ID BRWA0004