Des Moines River IA 04-UDM-1212

Assessment Comments

Assessment is based on: (1) water quality and fish contaminant monitoring conducted during the 2004-2006 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 et al. 2005, Lutz and Francois 2006, and Lutz and Francois 2007) 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 2004-2006 assessment period.

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, 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 2004-2006.   The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported” based on results of ambient chemical/physical monitoring from 2004-2006.   Fish consumption uses are assessed (monitored) as "fully supported" based on results of annual fish contaminant monitoring during the 2004-2006 period.   The assessments of support of the beneficial uses are based on results of (1) water quality and fish contaminant monitoring conducted during the 2004-2006 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 et al.  2005, Lutz and Francois 2006, and Lutz and Francois 2007) 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 2004-2006 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.   Due to recent changes in Iowa’s Water Quality Standards, Iowa’s assessment methodology for indicator bacteria has changed.   Prior to 2003, the Iowa WQ Standards contained a high-flow exemption for the Class A criterion for indicator bacteria (fecal coliforms) designed to protect primary contact recreation uses:  the water quality criterion for fecal coliform bacteria (200 orgs/100 ml) did not apply "when the waters [were] materially affected by surface runoff."  Due to a change in the Standards in July 2003, E.  coli is now the indicator bacterium, and the high flow exemption was eliminated and replaced with language stating that the Class A criteria for E.  coli apply when Class A1, A2, or A3 uses “can reasonably be expected to occur.”  Because the IDNR Technical Advisory Committee on WQ Standards could not agree on what flow conditions would define periods when uses would not be reasonably expected to occur, all monitoring data generated for E.  coli during the assessment period, regardless of flow conditions during sample collection, will be considered for determining support of Class A uses for purposes of Section 305(b) assessments and Section 303(d) listings.  

The results of ISU/ACOE monitoring at Sycamore access show that the geometric mean of the 36 samples collected during summers of 2004, 2005 and 2006 was 11 orgs/100 ml; none of the 36 samples 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 24 samples collected during summers of 2004, 2005 and 2006 was 20 orgs/100 ml; two of the 24 samples (8%) 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., and if less than 10% of the samples exceed the single-sample maximum criterion, 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 approximately 66 samples collected at this station during the 2004-2006 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 36 samples collected during the 2004-2006 assessment period exceeded Class B(WW1) criteria for dissolved oxygen, pH, or ammonia-nitrogen.   None of the 14 samples analyzed for toxic metals (including mercury), and none of the seven samples analyzed for pesticides, exceeded the respective Class B(WW1) criteria.  

Fish contaminant monitoring conducted downstream from Saylorville Reservoir by ISU/ACOE in 2004, 2005, and 2006 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 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 sampling season.   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 2004, 2005, or 2006 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 et al.  2005, Lutz and Francois 2006, and Lutz and Francois 2007).