Odebolt Creek IA 06-LSR-1592

Assessment Comments

Assessment remains based on results of IDNR/UHL biological (biocriteria) sampling in 1997: FIBI = 42 (fair), 34 (fair), FIBI ave = 38; BMIBI = 58 (good), 59 (good), BMIBI ave = 58.5. FIBI BIC = 31, BMIBI BIC = 54.

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:  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 (evaluted) as "fully supported" based on results of IDNR/UHL biological (biocriteria) sampling in 1997.   The 1997 biological sampling data are greater than five years old; therefore, this assessment is now considered "evaluated" instead of "monitored".

EXPLANATION:  The Class B(WW2) aquatic life uses remain assessed as "fully supported" based on results of the IDNR/UHL biocriteria monitoring conducted on this stream segment in 1997.   Sampling was conducted at two sites on this stream segment.   The FIBI scores were 42 and 34 (both in the "fair" category); the BMIBI scores were 58 and 59 (both good).   The FIBI average was 38 and the BMIBI average was 58.5.   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 FIBI BIC for this ecoregion is 31 and the BMIBI BIC for this ecoregion is 54.