West Branch One Hundred And Two River IA 05-PLA-1480

[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 DNR 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). This segment has remained on Iowa's subsequent Section 303(d) lists and remains on Iowa's Section 303(d) list. Iowa DNR’s original assessment for the 2004 Section 305(b) assessment cycle is included below.]

The Class B(WW1) aquatic life uses remain assessed (evaluated) as “partially supporting” based on data collected in 1995 as part of the DNR/SHL stream biocriteria project. The 1995 FIBI score was 25 (poor) 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 1994-2008. The FIBI BIC for this ecoregion is 31 and the BMIBI BIC for this ecoregion is 54. This segment passed the FIBI BIC (using the FIBI UAV of 7 points applied to single samples) and failed the BMIBI BIC in 2005 (by 1 point after adding the BMIBI UAV of 8 points applied to single samples).

This aquatic life assessment is considered "evaluated" because there were not two or more samples collected from this segment in multiple years. Additionally, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence). According to DNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). DNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation). However, despite this change in assessment methodology and type, this waterbody remains in IR Category 5b-t and remains on Iowa’s Section 303(d) lists of impaired waters.