Bear Creek IA 03-SSK-959

Assessment Comments

1997 bioassessments (spp./fam.): dstr Roland WWTP, 12/4; upstr Roland WWTP, 11/4. 1997 Biocriteria: upstream/downstream Fish IBI= 25(poor)/35(fair), BM-IBI= 58(good)/44(fair).

Basis for Assessment

The assessment was based on data collected in 1997 as part of the DNR/UHL stream biocriteria development 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 (F-IBI) and a benthic macroinvertebrate index (BM-IBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum)-100 (maximum).  

The F-IBI score upstream/downstream of the Roland wastewater treatment plant was 25(poor)/35(fair), and the BM-IBI score was 58(good)/44(fair).   The aquatic life use support status was assessed as partially supporting (=PS), based on a comparison of the F-IBI and BM-IBI scores with biological assessment criteria established specifically for the 2000 Section 305b report (IDNR 2000).   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-1998.