Floyd River IA 06-FLO-1554

Assessment Comments

Assessment is based on occurrence of fish kills in May 1997 and September 1998 (see attached document for details), and 1999 Biocriteria: Fish IBI= 32(fair), BM-IBI= 61(good).

Basis for Assessment

The assessment was based on the occurrence of fishkill events in 1997 and 1998, and data collected in 1999 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 1999 Fish IBI score was 32 (fair) and the BM-IBI score was 61 (good).  The aquatic life use support 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 2002 Section 305(b) report.  The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001.