Assessment Comments
Assessment remains based on results of monitoring for indicator bacteria conducted at Site 8 of the Upper Iowa River Watershed (UIRW) project from April 2004 through October 2006.
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(LR) aquatic life 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 now presumptively designated for Class A1 (primary contact recreation) uses. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current (2010) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" due to levels of indicator bacteria that exceeded state water quality criteria. The Class B(WW2) aquatic life uses remain “not assessed” due to the lack of information upon which to base an assessment. The source of data for this assessment is the results of monitoring for indicator bacteria conducted at Site 8 of the Upper Iowa River Watershed (UIRW) project (STORET No. NEIARCD 191910002) from April 2004 through October 2006.
EXPLANATION: The presumptive Class A1 (primary contact recreation) uses were assessed (monitored) as "not supported" due to violations of Iowa’s water quality criteria for indicator bacteria. The geometric mean of E. coli in the 21 samples collected UIRW site 8 during the recreational seasons of 2004 through 2006 was 707 orgs/100 ml. This geometric mean far exceeds the Class A1 criterion of 126 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean of E. coli is greater than the state criterion of 126 orgs/100 ml., the primary contact recreation uses should be assessed as "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).
The Class B(WW2) aquatic life uses remain “not assessed” due to the lack of information upon which to base an assessment.
