West Nishnabotna River IA 05-NSH-1444

Assessment Comments

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

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life uses remain "not assessed" due to the lack of water quality information upon which to base an assessment.   The fish consumption uses remain assessed (monitored) as "fully supported"  based on results of U.S.  EPA / IDNR fish tissue (RAFT) monitoring near Harlan in September 2001.  

EXPLANATION:  Due to the lack of data from either chemical or biological monitoring for this river reach, the assessment of support of the Class B(WW) uses remained "not assessed."  

Fish consumption uses remain assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Harlan in 2001.   The composite samples of fillets from channel catfish 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 West Nishnabotna 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.