East Branch West Nishnabotna River IA 05-NSH-1823
mouth (S29 T77N R39W Pottawattamie Co.) to confluence with unnamed outlet tributary from Prairie Rose Lake in S5 T78N R38W Shelby Co.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 9/22/2016 12:51:56 PM
- Updated
- 10/11/2016 12:14:57 PM
The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses are assessed (evaluated) as "partially supported" (IR 3b-c) based on results of IDNR/SHL biological (biocriteria) sampling in 2000, 2007 and 2011.
The Class B(WW2) aquatic life uses are assessed as “partially supported” based on biological data collected in 2000, 2007 and 2011 approximately 4.5 miles northeast of Avoca as part of the IDNR/SHL stream biocriteria project. The 2000 FIBI score was 35 (fair) and the BMIBI score was 46 (fair). The 2007 BMIBI score was 43 (fair) and fish were not collected. The 2011 FIBI score was 27 (fair) and the BMIBI score was 37 (fair). The aquatic life use support was assessed 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 1/2 times and passed the BMIBI BIC 0/3 times in the last 15 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 recent five-year period (2008-2012) to be considered “monitored”. This segment had multiple samples collected in the previous 15 years; however, the multiple samples were not collected during over a recent five-year period. According to IDNR’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). IDNR 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).