Des Moines River IA 04-UDM-1212

Assessment Comments

Assessment is based on results of monitoring from 2002-04 by (1) Iowa State Univ. as part of the ACOE's Des Moines R. water quality study (including annual fish contaminant monitoring) and (2) IDNR/UHL ambient city monitoring.

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life uses are assessed (monitored) as "fully supported” based on results of ambient chemical/physical monitoring from 2002-04 (this river segment was not designated for Class A uses during the 2002-2004 assessment period).   Fish consumption uses are assessed (monitored) as "fully supported" based on results of annual fish contaminant monitoring during the 2002-04 period.   The assessments of support of the beneficial uses are based on results of (1) water quality and fish contaminant monitoring conducted during the 2002-2004 assessment period approximately two miles downstream from Saylorville Dam at Sycamore Access (NW 66th Street) by Iowa State University (under contract with the U.S.  Army Corps of Engineers) as part of the Des Moines River Water Quality Study (see Lutz and Cummings 2003, Lutz 2004, and Lutz et al.  2005) and (2) results of IDNR/UHL ambient city monitoring upstream from Des Moines also at the Sycamore Access (NW 66th Street; STORET station 10770002) during the 2002-2004 assessment period.  

EXPLANATION:  The Class B(WW) aquatic life uses are assessed (monitored) as "fully supported”.   Results from ISU/ACOE monitoring at the Sycamore Access station show no violations of Class B(WW) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the approximately 66 samples collected at this station during the 2002-2004 assessment period.   None of the 12 samples analyzed during this period for toxic metals contained levels above Class B(WW) criteria.    

Results from the IDNR city monitoring station at Sycamore Access also suggest that the Class B(WW) aquatic life uses are "fully supported."  None of the 36 samples collected during the 2002-2004 assessment period exceeded Class B(WW) criteria for dissolved oxygen, pH, or ammonia-nitrogen.   None of the 32 samples analyzed for toxic metals (including mercury), and none of the seven samples analyzed for pesticides and other toxic organic compounds, exceeded Class B(WW) criteria.  

Fish contaminant monitoring conducted downstream from Saylorville Reservoir by ISU/ACOE in 2002, 2003, and 2004 showed low levels of contaminants (dieldrin, heptachlor epoxide, chlordane, alachlor, trifuluralin, and chlorpyrifos) in composite samples of whole fish and fillets of common carp.   In addition to these pesticide parameters, composite samples fillets from common carp and channel catfish from this station were analyzed in 2004 for mercury (the first analysis of fish tissue samples for mercury conducted as part of the ISU/ACOE program since 1994).   Based on this information, fish consumption uses are assessed as "fully supported".   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.   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 2002, 2003, or 2004 ISU/ACOE sampling (or from previous ISU/ACOE monitoring) conducted in the segment of the Des Moines River downstream from Saylorville Reservoir:  the levels of contaminants (chlordane and mercury) do not exceed any of the new (2006) advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.

For more information on ISU/ACOE water quality monitoring in this river reach, see (see Lutz and Cummings 2003, Lutz 2004, and Lutz et al.  2005).