The Class A1 (primary contact recreation) are assessed as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria.  The geometric means of indicator bacteria (E. coli) in the 24 samples collected during the recreational seasons of 2012 through 2014 at Little Sioux River near Milford were as follows: the 2012 geometric mean was 102 orgs/100 ml, the 2013 geometric mean was 112 orgs/100 ml, and the 2014 geometric mean was 159 orgs/100 ml.  One of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml.  Eleven of the combined 24 samples (46%) 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 "partially supported"

The assessment of the Class B(WW1) aquatic life uses was based on data collected in 2011 and 2014 as part of the IDNR/SHL stream biocriteria project.  The 2011 FIBI score was 60 (good) and the BMIBI score was 54 (fair).   The 2014 FIBI score was 41 (fair) and the BMIBI score was 50 (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 riffle site FIBI BIC for this ecoregion is 53 and the BMIBI BIC for this ecoregion is 62.   This segment passed the FIBI BIC 1/2 times and passed the BMIBI BIC 0/2 times in the last five years.  

This aquatic life assessment is also considered "monitored" because of 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 in a recent five year period to be considered “monitored”.   This segment had multiple samples collected in the previous five years.

Ambient chemical/physical water quality monitoring at the IDNR/SHL station near Milford show no violations of Class B(WW1) water quality criteria for 35 Ammonia samples (maximum = 1.4 mg/L), 35 pH samples (range = 7.3 to 8.9), 36 Temperature samples (maximum = 29.6° c), 36 Chloride samples (maximum = 43 mg/L), or 36 Sulfate samples (maximum = 240 mg/L) occurred during monitoring from January 2012 to December 2014. One of the 36 samples (3%) analyzed for Dissolved Oxygen (minimum = 4.4 mg/L) violated the Class B(WW1) criteria during the 2012-2014 monitoring period. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17), a violation frequency of greater than 10% for conventional parameters such as Dissolved Oxygen suggests impairment of aquatic life uses. Because the frequency of violations for this parameter is not greater than 10 percent, these results do not suggest impairment of the Class B(WW1) aquatic life uses.Although violations of the Class B(WW1) criteria for dissolved oxygen have occasionally (historically) occurred in this assessment segment, there has not been a dissolved oxygen violations in results of ambient monthly monitoring since February 2004.  

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