The Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" based on results of monitoring for indicator bacteria during the recreational seasons of 2012-2014.  The geometric means of indicator bacteria (E. coli) in the 24 samples collected during the recreational seasons of 2012 through 2014 at Otterville Access station were as follows:  the 2012 geometric mean was 228 orgs/100 ml, the 2013 geometric mean was 193 orgs/100 ml and the 2014 geometric mean was 84 orgs/100 ml.  The 2014 geometric mean was below the Class A1 criterion of 126 orgs/100 ml; the 2012 and 2013 geometric means are slightly above the Class A1 criterion.  These results are consistent with the history of generally low levels of indicator bacteria in this river segment.  Also, seven of the 24 samples (29%) exceeded the 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 a recreation season geometric mean exceeds the respective water quality criterion, the 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 “impaired.”

The Class B(WW1) (aquatic life) uses are assessed (evaluated) as "partially supported" based on results of IDNR/SHL biological sampling conducted from 2012-2014 as part of the large river/stream nutrient sampling projects and on data collected in 2004 by the IDNR Fisheries Bureau.  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 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 score was 48 (fair).  The 2012, 2013 and 2014 BMIBI scores were 67 (good), 45 (fair) and 21 (poor).  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 from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008.  The non-riffle FIBI BIC for this ecoregion is 44 and the artificial substrate BMIBI BIC for this ecoregion is 52.  This assessment is considered evaluated because the drainage areas (905 and 909 mi2) above the sampling sites were greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria.  Even though this site passed the FIBI BIC in 2004 and failed the BMIBI BIC (1/3 times) in the last five years, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because the sites used for the assessment don't fall in the calibrated watershed size.

In contrast to the biological sampling data, the water quality sampling data suggest that the Class B(WW1) aquatic life uses be assessed (monitored) as "fully supported".  In the approximately 36 samples collected at the IDNR station during the 2012-2014 period, there were no violations of state water quality criteria for pH, temperature, dissolved oxygen, ammonia-nitrogen, chloride, or sulfate. 

The fish consumption uses remain “not assessed” due to the lack of recent fish tissue monitoring in this river segment.