Little Sioux River IA 06-LSR-1571

Assessment Comments

Assessment remains based on results of U.S. EPA / IDNR fish tissue (RAFT) monitoring near Linn Grove in 2001.

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the Little Sioux River (IA 06-LSR-0030-1), which extended 38 miles from the Highway 3 at Cherokee (Cherokee Co.) (approximately equal to confluence with Mill Creek north of Cherokee) to the Linn Grove Dam (Buena Vista Co.), was split into two subsegments:  (1) Highway 3 at Cherokee to confluence with Waterman Creek (O'Brien Co.) (IA 06-LSR-0030-1) and (2) Waterman Creek to the Linn Grove Dam (Buena Vista Co.) (IA 06-LSR-0030-2 - this one).   See previous Section 305(b) assessments for IA 06-LSR-0030_1 for the assessments of the original 38-mile river reach.]

SUMMARY:  The Class A1 (primary contact recreation) uses and the Class B(WW) aquatic life uses remain "not assessed" due to the lack of water quality information upon which to base an assessment.   Fish consumption uses remain assessed (evaluated) as "fully supported" based on results of U.S.  EPA / IDNR fish tissue (RAFT) monitoring in 2001 downstream from the Linn Grove dam.   Because the data upon which this assessment is based are now older than five years, the assessment types is changed from "monitored" (a higher confidence assessment) to "evaluated" (a lower confidence assessment.   This assessment is also used for the adjacent upstream segment of the Little Sioux River (IA 06-LSR-0030-3).  

EXPLANATION:  The Class A1 and Class B(WW1) uses remain "not assessed" due to the lack of relevant water quality information for this segment.  

Fish consumption uses remain assessed (evaluated) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Linn Grove Dam in 2001.   The composite samples of fillets from channel catfish and walleye had low levels of contaminants.   The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses.   Prior to 2006, IDNR used action levels published by the U.S Food and Drug Administration to determine whether consumption advisories should be issued for fish caught as part of recreational fishing in Iowa.   In an effort to make Iowa’s consumption more compatible with the various protocols used by adjacent states, the Iowa Department of Public Health, in cooperation with Iowa DNR, developed a risk-based advisory protocol.   This protocol went into effect in January 2006 (see http://www.iowadnr.gov/fish/news/consump.html for more information on Iowa’s revised fish consumption advisory protocol).   Because the revised (2006) protocol is more restrictive than the previous protocol based on FDA action levels; fish contaminant data that previously suggested “full support” may now suggest either a threat to, or impairment of, fish consumption uses.   This scenario, however, does not apply to the fish contaminant data generated from the 2001 RAFT sampling conducted in this segment of the Little Sioux River:  the levels of contaminants do not exceed any of the new (2006) advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.