Assessment Comments
Assessment is based on results of IDNR/UHL biological (biocriteria) monitoring in 1995: FIBI = 27 (fair), BMIBI = 45 (fair). FIBI BIC = 31, BMIBI = 54.
Basis for Assessment
[Note: Although originally placed in Category 3b of Iowa's 2004 Integrated Report by Iowa DNR, U.S. EPA Region VII, in their May 23, 2006 transmittal of Iowa's final approved 2004 Section 303(d) list, added this waterbody segment to Iowa's 2004 Section 303(d) list (IR Category 5b). Iowa DNR maintained that the data used for this assessment were too old (more than five years) to accurately characterize current water quality conditions. Thus, this assessment was considered of lower confidence (i.e., "evaluated"), and this "partially supported" waterbody was thus considered not appropriate for Section 303(d) listing. U.S. EPA Region VII, however, stated that IDNR did not provide waterbody-specific data or information which supported its conclusion that the bioassessment data pertaining to this stream were not representative of current water quality conditions nor was EPA aware of any information which suggested that these data were not representative. Thus, EPA added-back this assessment segment to Iowa's 2004 final approved Section 303(d) list (Category 5b). Iowa DNR’s original assessment for the 2004 Section 305(b) assessment cycle is included below.]
SUMMARY: The Class B(WW) aquatic life uses remain assessed as "partially supported" based on results of biological monitoring and habitat assessment conducted as part of the IDNR/UHL biocriteria sampling in October 1995. Due to the age of the data, assessment category is changed from "monitored" (higher-confidence assessment) to "evaluated" (lower-confidence assessment). Fish consumption uses remain "not assessed."
EXPLANATION: The assessment was based on data collected in 1995 as part of the DNR/UHL stream biocriteria project. The 1995 FIBI score was 27 (fair) and the BMIBI score was 45 (fair). The aquatic life use support was assessed (evaluated) as partially supporting (=PS), 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 natural artificial substrate BMIBI BIC for this ecoregion is 54.
Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.
