Pratt Creek IA 02-CED-522

Assessment Comments

Assessment based on results of IDNR/UHL biological (biocriteria) monitoring in 2000: FIBI = 53 (good), BMIBI = 66 (good). Non-riffle site FIBI BIC = 44 and artificial substrate BMIBI BIC = 52.

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses are assessed (monitored) as "fully supported" based on results of IDNR/UHL biological (biocriteria) sampling in 2000.  

EXPLANATION:  This assessment was based on data collected in 2000 as part of the DNR/UHL stream biocriteria 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 that were 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 2000 FIBI score was 53 (good) and the BMIBI score was 66 (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 non-riffle site FIBI BIC for this ecoregion is 44 and the artificial substrate BMIBI BIC for this ecoregion is 52 .