Assessment Comments

Assessment based on 2007, 2010 and 2011 IDNR/UHL biological monitoring data: FIBI = 51, 59 and 63 (good); BMIBI = 64, 69 and 72 (good). FIBI BIC = 52, BMIBI BIC = 61.

Basis for Assessment

[Note:  Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(WW) aquatic life uses, including fish consumption uses.   Due to changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008, this segment is also now presumptively designated for Class A1 (primary contact recreation) uses.   This segment remains designated for warmwater aquatic life use (now termed Class B(WW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).]  

SUMMARY:  The presumptive Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment.   The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported" based on results of IDNR/UHL biological (biocriteria) sampling in 2007, 2010 and 2011.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.  

EXPLANATION:  This Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported" based on biological data collected in 2007, 2010 and 2011 as part of the IDNR/UHL stream biocriteria project.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biological 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 2007 FIBI score was 51 (good) and the BMIBI score was 72 (good).   The 2010 FIBI score was 63 (good) and the BMIBI score was 64 (good).   The 2011 FIBI score was 59 (good) and the BMIBI score was 69 (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 FIBI BIC for this ecoregion is 52 and the BMIBI BIC for this ecoregion is 61.   This segment passed the FIBI BIC 2/3 times and passed the BMIBI BIC 3/3 times in the last four years.   The biological impairment criteria were determined from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2004.  

This assessment is considered "monitored" because there were two or more samples collected from this segment in multiple years from 2006-2011.  

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.