[Note:  Prior to the 2008 Section 305(b) cycle, this river segment was designated only for Class B(WW1) 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) and the results of an Use Attainability Analysis, this segment is also now 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).]

The Class A1 (primary contact recreation) are assessed (monitored) as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria.  The geometric means of indicator bacteria (E. coli) in the 23 samples collected by USGS during the recreational seasons of 2012 through 2014 at the Little Sioux River near Turin were as follows: the 2012 geometric mean was 93 orgs/100 ml, the 2013 geometric mean was 44 orgs/100 ml, and the 2014 geometric mean was 807 orgs/100 ml.  One of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml.  Seven of the combined 23 samples (30%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml.

The geometric means of indicator bacteria (E. coli) in the 5 samples collected by IDNR during the recreational seasons of 2012 through 2014 at the Little Sioux River near Turin were as follows: the 2012 geometric mean was 1426 orgs/100 ml, the 2013 geometric mean was 0 orgs/100 ml, and the 2014 geometric mean was 236 orgs/100 ml.  Two of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml.  Three of the combined 5 samples (60%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml.

According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as "not supported".

Based exclusively on the results of water quality monitoring by the USGS and IDNR near Turin from 2012-2014, the Class B(WW1) aquatic life uses should be assessed (monitored) as "fully supported".   In the combined 41 samples collected during the 2012-14 period (32 by USGS and 9 by IDNR), there were no violations of state water quality criteria for dissolved oxygen, pH, temparature, ammonia-nitorgen, chloride, or sulfate.  No violations of the Class B(WW1) criteria for chlorpyrifos or dieldrin occurred in the 32 samples analyzed by USGS.  These results suggest "full support" of the Class B(WW1) aquatic life uses.   None of the 32 samples analyzed by USGS for DDE and dieldrin exceeded the respective human health-fish criteria.

In contrast to the water quality aquatic life assessment, the aquatic life assessment based on biological sampling suggests the aquatic life uses are "partially supporting".   This evaluated biological assessment was based on data collected in 2012 and 2013 as part of the IDNR/SHL stream nutrient sampling project.   A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biological sampling data.   The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa collected in the stream sampling reach.   The biological metrics were combined a benthic macroinvertebrate index (BMIBI).   The index rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2012 BMIBI score was 30 (poor) and the 2013 BMIBI score was 57 (good).  The aquatic life use support was assessed (evaluated) as partially supporting (=PS), based on a comparison of the BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008.   The BMIBI BIC for this ecoregion is 54.   This assessment is considered evaluated because the drainage area (4426 mi2) above this sampling site was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria.   Even though this site failed the BMIBI BIC (1/2), it is uncertain as to whether or not this segment is meeting the aquatic life criteria because the site used for the assessment doesn’t fall in the calibrated watershed size.   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).

Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this river reach.