Little Sioux River IA 06-LSR-1567

Assessment Comments

Assessment is based on results of U.S. EPA / IDNR fish tissue (RAFT) monitoring near Washta (Cherokee Co.) in 2008, 2010, and 2012.

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 and the Class B(WW1) aquatic life uses remain "not assessed" (IR 3a) due to the lack of water quality information upon which to base an assessment.    The fish consumption uses remain assessed (monitored) as "fully supported" (IR 2a) based on results of U.S.   EPA/IDNR fish tissue (RAFT) monitoring near Washta (Cherokee Co.) in 2008, 2010, and 2012.    This assessment is the same as that used for the adjacent downstream segment (IA 06-LSR-0020-2).  

EXPLANATION:  The Class A1 (primary contact recreation) uses and the Class B(WW1) aquatic life uses remain "not assessed" due to the lack of sufficient water quality information upon which to base an assessment for this river reach.    

Fish consumption uses are assessed (monitored) as "fully supported" based on the 2008 and 2010 EPA/IDNR fish tissue (RAFT) sampling on the Little Sioux River south of Washta (U.S.   EPA STORET station 008713).    This site has been sampled for whole-fish common carp since 1994 on an every-other-year basis as part of RAFT trend monitoring.    The results from the 2008 and 2010 samplings show low levels of the primary contaminants (chlordane, PCBs and mercury) in the composite whole-fish samples of common carp: 2008 sample:  mercury: 0.0636 ppm; total PCBs: 0.09 ppm; and technical chlordane:  <0.03 ppm; 2010 sample: mercury: 0.044 ppm; total PCBs: 0.09 ppm; and technical chlordane:  <0.03 ppm.    The results of the 2012 sampling are similar with all contaminant levels in the composite sample of whole-fish common carp well-below advisory thresholds:  mercury:  0.062 ppm; total PCBS:  0.09 ppm, and chlordane:  <0.03 ppm.    The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes.    The fish contaminant data generated from the 2008, 2010, and 2012 RAFT sampling conducted at this river segment show that the levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.