Long Creek IA 02-IOW-660

Assessment Comments

Assessment is based on results of IDNR/UHL biological (biocriteria) monitoring in 2001: FIBI = 58 (good), BMIBI = 53 (fair). FIBI BIC = 36, BMIBI BIC = 51.

Basis for Assessment

[Note:  Prior to the current (2008) Section 305(b) cycle, this river 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) and due to the completion of a Use Attainability Analysis, 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(WW2) uses).]

SUMMARY:  The Class A1 (primary contact recreation) uses are "not assessed" due to the lack of information upon which to base an assessment.   The Class B(WW-2) aquatic life uses are assessed (evaluated) as "fully supported" based on results of IDNR/UHL biocriteria monitoring in 2001.   The 2001 sampling data are now greater than five years old; therefore, this assessment is now considered "evaluated" instead of "monitored".

EXPLANATION:  The assessment of the Class B(WW2) aquatic life uses remains based on data collected in 2001 as part of the IDNR/UHL stream biocriteria project.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria 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 2001 FIBI score was 58 (good) and the BMIBI score was 53 (fair).  The aquatic life use support was assessed (evaluated) 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 36 and the BMIBI BIC for this ecoregion is 51.