Assessment Comments
Assessment based on 2004 and 2005 biocriteria data: 2004 FIBI = 64 (good), 36 (fair) and 2005 FIBI = 54 (good); 2004 BMIBI = 37 (fair), 35 (fair) and 2005 BMIBI = 20 (poor). FIBI ave (n=3)= 51 (good) and BMIBI ave (n=3) = 31 (fair). FIBI BIC = 36; BMIBI BIC = 51.
Basis for Assessment
[Note: Prior to the current (2008) Section 305(b) cycle, this stream segment was designated only for Class B(WW) aquatic life uses, including fish consumption 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 also now presumptively designated for Class A1 (primary contact recreation) uses. This segment remains designated for warmwater aquatic life use (now termed Class B(WW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).]
SUMMARY/EXPLANATION: The presumptive Class A1 (primary contact recreation) uses are "not assessed" due to the lack of information upon which to base an assessment.
The assessment of the Class B(WW1) aquatic life uses was based on data collected in 2004 and 2005 as part of the DNR/UHL stream biocriteria project. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2004 FIBI scores were 64 (good), 36 (fair) and 2005 FIBI score was 54 (good). The 2004 BMIBI score was 37 (fair), 35 (fair) and 2005 BMIBI score was 20 (poor). The FIBI average was (n=3) 51 (good) and the BMIBI average (n=3) was 31 (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 1994-2004. The FIBI BIC for this ecoregion is 36 and the BMIBI BIC for this ecoregion is 51.
Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this assessment segment.
