Boone River IA 04-UDM-1257

Assessment Comments

Assessment based on 2003 IDNR/UHL stream REMAP biological sampling data: FIBI = 32 (fair). Non-riffle habitat FIBI BIC = 32.

Basis for Assessment

[Note:  Prior to the current (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 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf) and due to the results of an Use Attainability Analysis in 2007, this segment is also now 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/EXPLANATION:  The Class A1 (primary contact recreation) uses are "not assessed" due to the lack of information upon which to base an assessment.

The assessment of the Class B(WW1) aquatic life uses was based on data collected in 2003 as part of the DNR/UHL stream REMAP 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 fish species collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (FIBI).   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 32 (fair).   The aquatic life use support was assessed (evaluated) as Fully Supporting (=FS), based on a comparison of the FIBI score 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 non-riffle habitat FIBI BIC for this ecoregion is 32.
This reason IDNR considered this assessment evaluated, rather than monitored, is because a benthic macroinvertebrate sample was collected at the sampling site; however, the artificial substrates were not colonized enough to calculate a BMIBI.   While low benthic macroinvertebate colonization does not automatically equate to impairment or a water quality problem, it does mean follow-up sampling should be explored.