Dibble Creek IA 01-TRK-203

Assessment Comments

Assessment is based on results of IDNR/UHL biological (biocriteria) sampling in 2004: FIBI = 45 (fair), BMIBI = 60 (good). FIBI BIC = 52; BMIBI BIC = 61.

Basis for Assessment

SUMMARY:  This evaluated biological assessment was based on data collected in 2004 as part of the DNR/UHL stream biocriteria project.   A series of biological metrics that 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 2004 FIBI score was 45 (fair) and the BMIBI score was 60 (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 from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The FIBI BIC for this ecoregion is 52 and the BMIBI BIC for this ecoregion is 61.   Even though this site passed both the FIBI and BMIBI BICs, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it is a small general use stream and doesn’t fall in the calibrated watershed size.