Soap Creek IA 04-LDM-1032

Assessment Comments

Assessment based on 2002 and 2010 IDNR/UHL biological monitoring data: FIBI = 34 (fair) and 51 (good), BMIBI = 46 (fair). FIBI BIC = 33; BMIBI BIC = 41.

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 remain assessed (evaluated) as "fully supported" based on results of IDNR/UHL biological (biocriteria) sampling in 2002 and 2010.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.  

EXPLANATION:  The presumptive Class B(WW1) aquatic life uses are assessed (evaluated) as “fully supporting” based on biological data collected in 2002 and 2010 as part of the IDNR/UHL stream biocriteria project.   The 2010 FIBI score was 51 (good) and the BMIBI score was unavailable.   The 2002 FIBI score was 34 (fair) and the BMIBI score was 46 (fair).   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 FIBI BIC for this ecoregion is 33 and the BMIBI BIC for this ecoregion is 41.   This segment passed the FIBI BIC 2/2 and BMIBI BIC 1/1 times in the past nine years.  

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology.   IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a five-year period to be considered “monitored”.   This segment had multiple samples collected in the previous nine years (2002-2010); however, the multiple samples were not collected during a five-year period.   Despite this change in assessment methodology and type, this waterbody remains in IR Category 2a.