Des Moines River IA 04-UDM-1212

Assessment Comments

Assessment is based on: (1) water quality and fish contaminant monitoring conducted during the 2006-2008 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 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 2006-2008 assessment period.

Basis for Assessment

[Note:  Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(WW) 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), this segment is also now presumptively 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 presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as "fully supported" based on monitoring of indicator bacteria from 2006-2008.   The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported” based on results of ambient chemical/physical monitoring from 2006-2008.   Fish consumption uses are assessed (monitored) as "fully supported" based on results of annual fish contaminant monitoring during the 2006-2008 period.   The assessments of support of the beneficial uses are based on results of (1) water quality and fish contaminant monitoring conducted during the 2006-2008 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 Francois 2007, Lutz and Francois 2008, and Lutz and Steffen 2009) 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 2006-2008 assessment period.  

EXPLANATION:  The presumptive Class A1 uses are assessed (monitored) as "fully supported" based on results of ambient water quality monitoring conducted by  both ISU/ACOE and IDNR/UHL approximately two miles downstream from Saylorville Dam at Sycamore Access.   The results of ISU/ACOE monitoring at Sycamore access show that the geometric mean of the 34 samples collected during summers of 2006, 2007 and 2008 was 11 orgs/100 ml; two of the 34 samples (6%) exceeded the 235 organism/100 ml single sample maximum criterion.   The results of IDNR/UHL monitoring at this station show that the geometric mean of the 22 samples collected during summers of 2006-2008 was 15 orgs/100 ml; none of the 22 samples exceeded the 235 organism/100 ml single sample maximum criterion.   These results, combined with results of previous monitoring, continue to indicate (1) extremely low levels of indicator bacteria in this reach of river and (2) that the lowest levels of indicator bacteria in the state’s streams and river occur immediately downriver from Iowa’s federal flood control reservoirs.   According to U.S.  EPA guidelines for Section 305(b) reporting, if the geometric mean of E.   coli is less than the state criterion of 126 orgs/100 ml., the primary contact recreation uses should be assessed as "fully supported" (see pgs 3-33 to 3-35of U.S.  EPA 1997b).    

The Class B(WW1) aquatic life uses are also assessed (monitored) as "fully supported.”  Results from ISU/ACOE monitoring at the Sycamore Access station show no violations of Class B(WW1) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the 64 samples collected at this station during the 2006-2008 assessment period.   None of the 12 samples analyzed during this period for toxic metals contained levels above the respective Class B(WW1) criteria.    

Results from the IDNR city monitoring station at Sycamore Access also suggest that the Class B(WW1) aquatic life uses are "fully supported."  None of the 34 samples collected during the 2006-2008 assessment period exceeded Class B(WW1) criteria for dissolved oxygen, pH, or ammonia-nitrogen.   None of the 4 samples analyzed for toxic metals (including mercury), and neither of the two samples analyzed for pesticides, exceeded the respective Class B(WW1) criteria.  

Fish contaminant monitoring conducted downstream from Saylorville Reservoir by ISU/ACOE in 2006, 2007, and 2008 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 for mercury in 2004, and composite fillet samples from common carp and largemouth bass were analyzed for mercury in 2005 (this was the first analysis of fish tissue samples for mercury conducted as part of the ISU/ACOE program since 1994).   The results showed low levels of mercury in these samples:  common carp:  0.06 ppm in 2004 and 0.04 ppm in 2005; channel catfish fillets:  0.13 ppm in 2004; largemouth bass fillets:  0.11 ppm in 2005.   This supplemental monitoring for mercury in fish was not conducted during the 2006-2008 sampling seasons.   Based on this information, fish consumption uses are assessed (monitored) 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.   The fish contaminant data generated from the 2006, 2007, or 2008 ISU/ACOE samplings (or from previous ISU/ACOE monitoring) conducted in the segment of the Des Moines River immediately downstream from Saylorville Reservoir show that levels of contaminants (chlordane and mercury) do not exceed any of the IDPH/IDNR 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 Lutz and Francois 2007, Lutz and Francois 2008, and Lutz and Steffen 2009; the URL for the Des Moines River Water Quality Monitoring Network web site is http://home.eng.iastate.edu/~dslutz/dmrwqn/dmrwqn.html.