The presumptive Class A1 uses are assessed (monitored) as "partially supported" based on results of ambient monitoring for indicator bacteria (E. coli).  The geometric means of indicator bacteria (E. coli) in the 25 samples collected during the recreational seasons of 2012 through 2014 at IDNR station 10910003 near Ackworth were as follows:  the 2012 geometric mean was 440 orgs/100 ml, the 2013 geometric mean was 269 orgs/100 ml, and the 2014 geometric mean was 596 orgs/100 ml.  All three geometric means exceed the Class A1 criterion of 126 orgs/100 ml.  Thirteen of the 25 samples (52%) 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(WW2) aquatic life uses are assessed (monitored) as "fully supported”.  None of the approximately 36 samples collected during the 2012-2014 assessment period at the IDNR/SHL monthly station violated Class B(WW2) water quality criteria for pH, temperature, ammonia-nitrogen, chloride, or sulfate.  One of the 36 samples (3%) had a level of dissolved oxygen (3.2 mg/l) that violated the Class B(WW2) criterion of 5.0 mg/l.  According to U.S. EPA guidelines for Section 305(b) reporting (U.S. EPA 1997b:  page 3-17), a violation frequency for conventional parameters such as dissolved oxygen of less than 10% does not suggest an impairment of aquatic life uses.  Thus, the results of chemical/physical water quality monitoring from 2012-2014 suggest “full support” of the Class B(WW2) aquatic life uses.