South Fork Maquoketa River IA 01-MAQ-58

Assessment Comments

Assessment remains based on 2005 IDNR/UHL biological monitoring data: FIBI = 48 (fair), BMIBI = 59 (good) and 2004 IDNR Fisheries bureau data: FIBI = 53 (good). Non-riffle habitat FIBI BIC = 44; artificial substrate BMIBI BIC = 52.

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 (2012) 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" due to the lack of information upon which to base an assessment.   The Class B(WW2)aquatic life uses are assessed (monitored) as "fully supporting" based on data collected in 2005 as part of the IDNR/UHL stream REMAP project and data collected in 2004 by IDNR Fisheries Bureau: Manchester Research Station.  

EXPLANATION:  The assessment of the Class B(WW2) aquatic life uses was based on data collected in 2005 as part of the IDNR/UHL stream REMAP project and data collected in 2004 by IDNR Fisheries Bureau: Manchester Research Station.   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 2005 FIBI score was 48 (fair) and the BMIBI score was 59 (good).   The 2005 Fisheries FIBI score was 53 (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 non-riffle habitat FIBI BIC for this ecoregion is 44 and the artificial substrate BMIBI BIC for this ecoregion is 52.   The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.

This aquatic life assessment is considered "monitored" because there were two or more samples collected from this segment in multiple years over a five-year period.   Because, however, these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).