Assessment Comments
Assessment based on results of IDNR/UHL biological (biocriteria) monitoring in 2002: Fish IBI= 12 (poor), BM-IBI= 71 (good).
Basis for Assessment
SUMMARY: The Class B(LR) aquatic life uses are assessed (evaluated) as "partially supported" based on results of IDNR/UHL biological (biocriteria) sampling in 2002.
EXPLANATION: The assessment was based on data collected in 2002 as part of the DNR/UHL stream biocriteria project. The 2002 Fish IBI score was 12 (poor) and the BM-IBI score was 71 (good). The aquatic life use support was assessed as partially supporting (=PS), based on a comparison of the F-IBI and BM-IBI scores with biological assessment criteria established for previous Section 305(b) reports. The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001. Because the fish sampling conditions were considered as less than optimum due to water depth and turbidity, and because the sample site watershed size is larger than the reference site watershed calibration range, the assessment was rated as "evaluated" (lower confidence assessment) rather than "monitored" (higher confidence assessment). For this assessment, the drainage area for the segment (just over 500 mi2) exceeds the maximum drainage area cutoff (500 mi2) that IDNR has established for use of BMIBI and FIBI data. Therefore, IDNR considers the aquatic life use impairments indicated by these data as “evaluated” assessments that are not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).
