East Branch West Nishnabotna River IA 05-NSH-1823

Assessment Comments

2000 Biocriteria: Fish IBI= 35(fair); BM-IBI= 45(fair).

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the East Branch West Nishnabotna River (IA 05-NSH-0140-0), which extended 31 miles from its mouth to confluence with Lone Willow Creek in Audubon County, was split into two subsegments:  (1) mouth to confluence with unnamed outlet tributary from Prairie Rose Lake (IA 05-NSH-0140-1) and (2) from confluence with unnamed outlet tributary from Prairie Rose Lake to confluence with Lone Willow Creek in Audubon Co.  (IA 05-NSH-0140-2).   See above for previous Section 305(b) assessments for the original 31-mile stream segment.]

The assessment was based on data collected in 2000 approximately 4.5 miles northeast of Avoca as part of the DNR/UHL stream biocriteria project.  The 2000 Fish IBI score was 35 (fair) and the BM-IBI score was 45 (fair).  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.