Mad Creek IA 01-NEM-1902

Assessment Comments

Assessment based on 2004 REMAP data: FIBI = 48 (fair), BMIBI = 71 (good). FIBI BIC = 36; BMIBI BIC = 51.

Basis for Assessment

SUMMARY:  This evaluated biological assessment was based on data collected in 2004 as part of the DNR/UHL stream REMAP 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 48 (fair) and the BMIBI score was 71 (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 35 and the BMIBI BIC for this ecoregion is 51.

This assessment is considered “evaluated” (of lower confidence) due to the lack of a biological assessment protocol for headwater streams.   Prior to the changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008, this stream was classified only for general uses due to the inability of the stream to support a viable aquatic community at low-flow conditions.   IDNR’s existing biological assessment protocol, however, was calibrated to aquatic life reference conditions in larger wadeable streams with perennial flow.