Presentation Abstract

Water-quality problems in urban and suburban streams are commonly blamed on stormwater pollution -- but actual stormflow pollutant data are much more limited. We analyzed 18 years (1993-2010) of stormflow metals concentrations from 33 stream stations across King County. We tested for long-term trends, compared stormflow and baseflow concentrations, and assessed aquatic and human-health toxicity. Five metals had long-term trends, all beneficial. Lead, nickel, and zinc concentrations have decreased over time. Calcium and magnesium concentrations have increased, which can reduce the adverse effects of toxic metals. In comparison to baseflow, 13 metals had discernably higher concentrations in stormflow (during 2001-2003 when metals were measured in baseflow). We assessed toxicity using state and federal regulatory water quality standards (WQSs), plus non-regulatory salmonid-specific screening values (SSVs). For aquatic toxicity, several samples were above WQSs for copper or lead, and 84% of streams had samples above the mercury chronic WQS. Ratios to WQSs were

Session Title

Stormwater Characterization and Management Using a Watershed Approach

Conference Track

SSE3: Fate, Transport, and Toxicity of Chemicals

Conference Name

Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)

Document Type

Event

SSEC Identifier

SSE3-375

Start Date

6-4-2018 10:30 AM

End Date

6-4-2018 10:45 AM

Type of Presentation

Oral

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)

Runoff--Washington (State)--King County; Runoff--Environmental aspects--Washington (State)--King County; Water--Pollution--Washington (State)--King County

Geographic Coverage

King County (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

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Apr 6th, 10:30 AM Apr 6th, 10:45 AM

Is stormwater harming our streams? Long-term monitoring of metals in stream stormflow

Water-quality problems in urban and suburban streams are commonly blamed on stormwater pollution -- but actual stormflow pollutant data are much more limited. We analyzed 18 years (1993-2010) of stormflow metals concentrations from 33 stream stations across King County. We tested for long-term trends, compared stormflow and baseflow concentrations, and assessed aquatic and human-health toxicity. Five metals had long-term trends, all beneficial. Lead, nickel, and zinc concentrations have decreased over time. Calcium and magnesium concentrations have increased, which can reduce the adverse effects of toxic metals. In comparison to baseflow, 13 metals had discernably higher concentrations in stormflow (during 2001-2003 when metals were measured in baseflow). We assessed toxicity using state and federal regulatory water quality standards (WQSs), plus non-regulatory salmonid-specific screening values (SSVs). For aquatic toxicity, several samples were above WQSs for copper or lead, and 84% of streams had samples above the mercury chronic WQS. Ratios to WQSs were