Bioassessment and Biocriteria Program Status for Illinois: Streams and Wadeable Rivers
State Program Contact
Water Quality Standards
The link to Illinois' WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
Water Quality Standards Regulations: Illinois
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Designated Aquatic Life Uses
The following Aquatic Life Uses (ALU) represent at least three different levels of potential biological condition. General Use and Upper Dresden Island Pool ALU represent biological condition consistent with the “balanced indigenous populations” aquatic-life goal of the Clean Water Act.
- General Use
- Upper Dresden Island Pool ALU
- Chicago Area Waterway System ALU A
- Chicago Area Waterway System and Brandon Pool ALU B
- Indigenous ALU (South Fork South Branch Chicago River only)
__X__ No criteria
What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates and fish
Are bioassessments used to support 303(d) listings?
Yes. Listing methodology: Integrated Water Quality Report and 303d Lists
How are assemblages used to make impairment decisions?
Each are applied independently
Other uses of biocriteria or bioassessment within the water quality program:
Refining ALU, TMDL development and assessment, antidegradation, non-point source assessments, 305(b) surface water condition assessments, and evaluation of discharge permit conditions.
Technical Support Information and Documents:
Illinois fish and macroinvertebrate biological indexes represent a measure of similarity to/dissimilarity from the expected least-disturbed biological condition that best pertains to the site being assessed.
Stressor identification/causal analysis approach:
Water chemistry and physical habitat are measured or otherwise assessed at the time of biological sampling.
Technical reference material:
Integrated Water Quality Report and 303d Lists