Upper Iowa River IA 01-UIA-245

Assessment Comments

Assessment is based on results of fish contaminant monitoring conducted near Lime Springs in 2006 as part of the U.S. EPA/IDNR fish contaminant (RAFT) monitoring program.

Basis for Assessment

[Note:  Prior to the current (2008) Section 305(b) cycle, this stream segment was designated only for Class B(WW) 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(WW1) aquatic life uses).   Thus, for the current (2008) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW1) water quality criteria.]

SUMMARY:  The pesumptive Class A1 (primary contact recreation) uses are “not assessed” due to the lack of information upon which to base an assessment.   The Class B(WW1) aquatic life uses are considered "not assessed" due to the age of the biological data upon which the previous assessments of these uses ("fully supported") were based.   Fish consumption uses are assessed (monitored) as “fully supported” based on results of fish contaminant monitoring conducted near Lime Springs in 2006 as part of the U.S.  EPA/IDNR fish contaminant (RAFT) monitoring program.  

EXPLANATION:  The presumptive Class A1 (primary contact recreation) uses were “not assessed” due to the lack of data for indicator bacteria upon which to base an assessment.

The Class B(WW1) aquatic life uses also remain “not assessed.”  The 2004 assessment of the Class B(WW) uses for this stream segment (“fully supported”) was based on results of biological monitoring conducted as part of an IDNR stream use assessment in 1995.   Because the data upon which this assessment was originally based have aged beyond 10 years--and are thus considered too old to characterize current water quality conditions--the Class B(WW1) uses of this segment are now considered "not assessed".  

Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Lime Springs in 2006.   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 (IDPH), 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).  

The composite samples of fillets from smallmouth bass and golden redhorse (Moxostoma erythrurum) collected near Lime Springs in 2006 were analyzed only for mercury.   These samples were collected as part of RAFT follow-up monitoring to better define the boundaries of the existing fish consumption advisory issued in 2006 for the Upper Iowa River from the Lower Dam upriver to the county road W20 bridge NW of Decorah.   The level of mercury in the composite sample of golden redhorse fillets was 0.22 ppm.   The level of mercury in the composite sample of smallmouth bass fillets was 0.25 ppm.   These results suggest that levels of mercury in fish from this segment of the Upper Iowa River are below IDNR/IDPH advisory trigger levels.   Thus, the fish consumption uses are assessed as “fully supported.”