Chequest Creek IA 04-LDM-1030

Assessment Comments

Assessment based on 2003 biocriteria data: FIBI = 45 (fair), BMIBI = 59 (good). FIBI BIC = 33; BMIBI BIC = 41.

Basis for Assessment

[Note:  Prior to the current (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 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), 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 (2008) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]

SUMMARY/EXPLANATION:  The presumptive Class A1 (primary contact recreation) uses are "not assessed" due to the lack of information upon which to base an assessment.  

The Class B(WW2) aquatic life uses remain assessed (monitored) as "fully supported" based on results of 2003 biological monitoring conducted as part of the IDNR/UHL stream biocriteria project.   These data are less than five years old and, according to IDNR's methodology for Section 305(b) assessments, are thus appropriate for characterizing current water quality conditions.

The assessment was based on data collected in 2003 as part of the DNR/UHL stream biocriteria project.  The 2003 FIBI score was 46 (fair) and the BMIBI score was 59 (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 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.