Assessment Comments
Assessment based on 2011-2013 IDNR/SHL biological sampling data: FIBI = 62, 69 (good) and 77 (excellent); BMIBI = 57, 69 (good) and 78 (excellent). Non-riffle habitat FIBI BIC = 44; natural substrate BMIBI BIC = 70.
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 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 remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW-2) aquatic life uses are assessed (monitored) as "partially supported" (IR 5b-v) based on results of IDNR/SHL biological sampling conducted in 2011, 2012 and 2013.
EXPLANATION: The Class B(WW2) aquatic life uses remain assessed (evaluated) as “partially supporting” based on data collected in 2011, 2012 and 2013 as part of the IDNR/SHL stream biocriteria project. The 2011 FIBI score was 69 (good) and the BMIBI score was 78 (excellent). The 2012 FIBI score was 62 (good) and the BMIBI score was 69 (good). The 2013 FIBI score was 77 (excellent) and the BMIBI score was 57 (good). 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 non-riffle habitat FIBI BIC for this ecoregion is 44 and the natural substrate BMIBI BIC for this ecoregion is 70. This segment passed the FIBI BIC 3/3 times and the BMIBI BIC 1/3 times in the last five years (2009-2013).
This aquatic life assessment is considered "monitored" because there were two or more samples collected from this segment in multiple years over a five-year period.
