Assessment Comments

Assessment is based on results of IDNR/UHL ambient monthly monitoring near Colfax from 2002-04 and the results from 2003 REMAP data: FIBI = 30 (fair), BMIBI = 57 (good). Non-riffle FIBI BIC = 32; BMIBI BIC = 62.

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses are assessed (evaluated) as "fully supported" based on results of ambient chemical/physical water quality monitoring and the biological monitoring results from a 2003 REMAP site.   The sources of data for this assessment are (1) results of IDNR/UHL monthly ambient monitoring conducted from 2002 through 2004 on Indian Creek at a bridge 4.8 miles north of Colfax and 1.8 miles east of Green Castle in Jasper County (station 10500001) and (2) IDNR/UHL biological (REMAP) monitoring near Mingo in 2003.

EXPLANATION:  Results of monitoring at the IDNR station show no violations of Class B(LR) criteria for dissolved oxygen, pH, or ammonia nitrogen (maximum value = 0.50 mg/l) in the 36 samples analyzed during the 2002-2004 assessment period, no violations of Class B(LR) chronic criteria for pesticides in the seven samples analyzed or for toxic metals in the 10 samples analyzed.   This assessment is consistent with the assessment developed for the previous (2004) Section 305(b) reporting cycle.

Additionally, the assessment was based on data collected in 2003 as part of the DNR/UHL stream REMAP project.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data.   The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2003 FIBI score was 30 (fair) and the BMIBI score was 57 (good).   The aquatic life use support was assessed (evaluated) as fully supporting (= FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports.  The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The non-riffle FIBI BIC for this ecoregion is 32 and the BMIBI BIC for this ecoregion is 62.   The assessment is considered FS-evaluated because both the FIBI and BMIBI scores met the respective BICs with the use of the UAVs (used on single samples): FIBI = 7 and BMIBI = 8.