Mississippi River IA 01-NEM-76

Assessment Comments

Assessment remains based on (1) LTRMP ambient monitoring near Guttenberg from 2002-04 and (2) U.S. EPA/IDNR fish contaminant monitoring in 2007 downstream from Guttenberg.

Basis for Assessment

SUMMARY:  The Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment.   The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supporting" based on results of ambient chemical water quality monitoring from 2002 through 2004.   Fish consumption uses remain assessed (monitored) as "fully supported" based on fish contaminant monitoring in 2007.   The sources of data used for this assessment are (1) the results of routine chemical/physical water quality monitoring conducted at station M615.2B at the Lock and Dam 10 tailwater at Guttenberg from January 2002 through September 2004 by IDNR staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at Bellevue, IA and (2) results of U.S.  EPA/DNR fish tissue (RAFT) monitoring in 2007 downstream from Guttenberg.  

EXPLANATION:  An assessment of support of the Class A1 (primary contact recreation) uses was not developed due to lack of sufficient data on levels of indicator bacteria in this river reach.   LTRMP monitoring does not include analysis for indicator bacteria.  

Results of water quality monitoring from LTRMP station M615.2B at the tailwater area of Lock and Dam 10 do not suggest water quality concerns with conventional parameters.   Results of monitoring from 2002-04 at this station show no violations of Class B(WW1) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the 17 samples collected.   Note:  LTMRP monitoring has not been conducted at this station since 2004.  

Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring downstream of Guttenberg in 2007.   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.   The composite samples of fillets from the 2007 RAFT sampling had low levels of contaminants.   Levels of primary contaminants in the composite sample of common carp fillets in 2007 were as follows: mercury: 0.126 ppm; total PCBs: 0.112 ppm; and technical chlordane: <0.03 ppm.   The level of mercury in the composite sample of white bass fillets was 0.065 ppm.   The levels of contaminants from the 2007 RAFT sampling do not exceed any of the advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.