Pine Creek IA 01-WPS-386

Assessment Comments

Assessment based on 2003 and 2011 IDNR/SHL biological sampling data: FIBI = 67, 69 (good); BMIBI = 76, 85 (excellent). Non-riffle habitat FIBI BIC = 44; natural substrate BMIBI BIC = 70.

Basis for Assessment

[Note:  Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(LR) aquatic life uses.   Due to changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008, this segment is now presumptively designated for Class A1 (primary contact recreation) uses.   The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses).   Thus, for the current assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]

SUMMARY:  The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment.   The Class B(WW2) aquatic life uses are assessed (evaluated) as “fully supporting” (IR 2a) based on results of IDNR/SHL biological sampling in 2003 and 2011.  

EXPLANATION:  The assessment of the Class B(WW2) aquatic life uses was based on data collected in 2003 and 2011 as part of the IDNR/SHL 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 2003 FIBI score was 69 (good) and the BMIBI score was 76 (excellent).   The 2011 FIBI score was 67 (good) and the BMIBI score was 85 (excellent).   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 non-riffle habitat FIBI BIC for this ecoregion is 44 and the natural substrate BMIBI BIC for this ecoregion is 70.   This segment passed the FIBI BIC 2/2 times and passed the BMIBI BIC 2/2 times in the last 10 years.   The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008.  

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 10 years (2003-2012); however, the multiple samples were not collected during a five-year period.