Elk Run IA 02-CED-544

Assessment Comments

Assessment based on results of IDNR/UHL biological (biocriteria) monitoring in 1999: FIBI = 73 (excellent), BMIBI = 63 (good). Non-riffle FIBI BIC = 44, natural substrate BMIBI BIC = 70.

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses are assessed (evaluted) as "fully supported / threatened" (minor impacts) based on results of IDNR/UHL biological (biocriteria) sampling in 1999.   This is the same assessment as that developed for the 2004 reporting cycle except the data are now too old for the assessment to be considered monitored; therefore, this is an evaluated assessment..

EXPLANATION:  This assessment was based on 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 (FIBI) and a benthic macroinvertebrate index (BMIBI).   The indicies rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 1999 FIBI score was 73 (excellent) and the BMIBI score was 63 (good).   The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports.  The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The non-riffle site FIBI BIC for this ecoregion is 44 and the natural substrate BMIBI BIC for this ecoregion is 70.   This site passed the FIBI BIC and passed the BMIBI BIC using the UAV of 8 points.