Derivation of a Local Chloride Threshold for Wadeable Streams

Doohaluk, Deanna

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https://hdl.handle.net/2142/114145 Copy

Description

Title

Derivation of a Local Chloride Threshold for Wadeable Streams

Author(s)

Doohaluk, Deanna

Issue Date

2022-04-28

Keyword(s)

• road chemicals
• chloride

Abstract

Our derivation of a protective chloride threshold was based on first identifying the most chloride sensitive fish species and macroinvertebrate taxa from field data and the derivation of “weighted-mean” chloride values for each species/taxa. Low chloride weighted averages (i.e., sensitive) means that chloride sensitive taxa are more often absent at sites with high chloride concentrations and more often present at sites with low chloride concentrations relative to other species or taxa. Although a correlative approach, the large sample sizes used makes it more robust. A 20th percentile cutoff was used to identify sensitive species.   Fish were found to be more sensitive than macroinvertebrates so a chloride sensitive fish index of biointegrity (fIBI) was created. We derived the General Use chloride threshold as the 75th percentile chloride values at sites meeting the States fIBI threshold that also had > 25th percentile of sensitive fish chloride species. For wadeable streams in NE Illinois the General Use threshold generated was 120 mg/L. We also derived an Excellent category threshold using the same approach for sites.   FIT scores were used to test for variability around these thresholds. For chloride the FIT score was relatively strong.

Series/Report Name or Number

2022 Emerging Contaminants in the Environment Conference (ECEC22)

Type of Resource

• text
• still image

Language

en

Permalink

• https://youtu.be/mm9Evv21VSA
• http://hdl.handle.net/2142/114145

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