Assessment Comments

Assessment is based on results of USGS ambient water quality monitoring conducted on the Little Sioux near Turin from January 2006 to December 2008.

Basis for Assessment

[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).]

SUMMARY:  The Class A1 (primary contact recreation) uses are not assessed due to lack of data on indicator bacteria.   The Class B(WW1) aquatic life uses are assessed (monitored) as “fully supported” based on results of chemical water quality monitoring by USGS.   Fish consumption uses are “not assessed” due to the lack of fish contaminant monitoring in this river segment.   The source of data for this assessment is the results of USGS ambient water quality monitoring conducted on the Little Sioux near Turin from January 2006 to December 2008.

EXPLANATION:  The Class A1 (primary contact recreation) uses are not assessed due to lack of data on indicator bacteria.   The monitoring conducted by USGS near Turin did not include analysis for indicator bacteria.  

The Class B(WW1) aquatic life uses were assessed (monitored) as "fully supported" based on results of water quality monitoring by the U.S.  Geological Survey near Turin from 2006-2008.   No violations of state water quality criteria occurred in the approximately 34 samples analyzed for dissolved oxygen, pH, and ammonia.   No violations for DDE occurred in the approximately 34 samples collected from 2006 through 2008.   There was however one violation of the Class B(WW1) criterion for dieldrin (3%) and one violation of the Class B(WW1) chronic criterion for chlorpyrifos (3%).   According to IDNR's assessment methodology these results are not significantly greater than 10% of the samples and therefore do not suggest impairment of the Class B(WW1) uses.   These results suggest that the Class B(WW1) aquatic life uses should be assessed as “full supporting.”

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