Rock Creek IA 02-CED-586

Assessment Comments

Assessment is based on results on 1996 biocriteria sampling: 16 spp.; 5 fams; Fish IBI=54 (good); BM IBI=55 (fair).

Basis for Assessment

Assessment was based on data collected in August 1996 approximately 0.25 mi E of Rock Creek 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 (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) to 100 (maximum).

The F-IBI score was 54 (good) and the BM-IBI score was 55 (fair).   The aquatic life use support was assessed as partially supported (=PS), based on a comparison of the F-IBI and BM-IBI scores with biological assessment criteria established specifically for the 2000 Section 305(b) report.   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-1998.