South Fork Iowa River IA 02-IOW-748

Assessment Comments

Assessment based on 2003 REMAP data: FIBI = 73 (excellent), BMIBI = 73 (good). FIBI BIC = 53; BMIBI BIC = 62.

Basis for Assessment

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 73 (excellent) and the BMIBI score was 73 (good).   The aquatic life use support was assessed 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 FIBI BIC for this ecoregion is 53 and the BMIBI BIC for this ecoregion is 62.