Bear Creek IA 02-CED-517

Assessment Comments

Assessment based on results of IDNR/UHL biological (biocriteria) monitoring in 2001 and 2010: FIBI = 44 (fair), 52, 63 (good), BMIBI = 73, 70 (good), 53 (fair) and IDNR Fisheries Bureau fish sampling in 2005: FIBI = 51 (good). Non-riffle habitat FIBI BIC = 44, natural substrate BMIBI BIC = 70 and 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.]

[Note:  Due to the completion and approval of two use attainability analyses, portions of this assessment segment are now designated for Class A3 (children’s recreation) use while the remainder of the segment remains presumptively designated for Class A1 (primary contact recreation) use.   Because (1) the water quality criteria to protect Class A1 and A3 uses are identical and (2) incorporation of the new Class A3 designations would require four splits in this assessment segment, the entire segment (IA 02-CED-0231_0) will be assessed as a Class A1 (primary contact recreation) segment for the 2012 305(b)/303(d) cycle.]

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 (evaluated) as "fully supported" based on results of IDNR/UHL biological (biocriteria) sampling in 2001 and 2010 and one IDNR Fisheries Bureau fish sampling in 2005.  

EXPLANATION:  The Class B(WW2) aquatic life uses are assessed (evaluated) as “fully supporting” based on biological data collected in 2001 and 2010 as part of the IDNR/UHL stream biocriteria project and on fish data collected by the IDNR Fisheries Bureau in 2005.   The 2001 FIBI scores were 44 (fair) and 52 (good); the BMIBI scores were 73 (good) and 70 (good).   The 2005 Fisheries Bureau FIBI score was 51 (good).   The 2010 FIBI score was 63 (good) and the BMIBI score was 53 (fair).   The aquatic life use support was assessed (evaluated) as fully supported (=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 non-riffle habitat FIBI BIC for this ecoregion is 44, the natural substrate BMIBI BIC (2001 BMIBI samples) for this ecoregion is 70 and the artificial substrate BMIBI BIC for this ecoregion is 52 (2010 BMIBI sample).   This segment passed the FIBI BIC 4/4 times and passed the BMIBI BIC 3/3 times in the last 10 years.  

This aquatic life assessment is now considered "evaluated" 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”.    This segment had multiple samples collected in the previous 10 years (2001-2010); however, the multiple samples were not collected during a five-year period.   Despite this change in assessment methodology and type, this waterbody remains in IR Category 2a.