Little Maquoketa River IA 01-TRK-131

Assessment Comments

Assessment based on 2008 and 2012 IDNR/SHL biological sampling data: FIBI = 66, 67 (both good), BMIBI = 62, 70 (both 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, a portion of this segment is also now presumptively designated for Class A1 (primary contact recreation) uses and a portion is presumptively designated for Class A2 (secondary 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 and presumptive Class A2 (secondary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment.   The Class B(WW-1) aquatic life uses are assessed (monitored) as "fully supported" (IR 2a) based on results of IDNR/SHL biological sampling in 2008 and 2012.   Fish consumption uses remain "not assessed" (IR 3a) due to the lack of fish contaminant monitoring in this stream segment.  

EXPLANATION:  The presumptive Class A1 and Class A2 uses remain "not assessed" due to the lack of data for indicator bacteria upon which to base an assessment.  

The aquatic life uses are assessed (monitored) as "fully supporting" based on data collected in 2008 and 2012 as part of the IDNR/UHL stream biological monitoring 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 2008 FIBI score was 67 (good) and the BMIBI score was 70 (good).   The 2012 FIBI score was 66 (good) and the BMIBI score was 62 (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 2/2 times and passed the BMIBI BIC 2/2 times in the last five years.   The biological impairment criteria were determined from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008.  

This aquatic life assessment is now considered "monitored" 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”.  

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