Mississippi River IA 01-NEM-61

Assessment Comments

Assessment is based on (1) 2014 assessment information from the Illinois EPA (2) results of LTRMP ambient monitoring from 2002-04, and (3) results of fish tissue (RAFT) monitoring at three locations: (1) near Muscatine in 2005, 2006 and 2012, (2) near Buffalo (Scott Co.) in 2004, 2006, 2008, and 2009, and (3) near Linwood in 2006 and 2010.

Basis for Assessment

SUMMARY:  The Class A1 (primary contact recreation) uses are considered “not assessed” due to the lack of monitoring information upon which to base an assessment.   The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supported” (IR 2a) based on results of chemical/physical water quality monitoring conducted from 2002-2004.   Fish consumption uses are assessed (monitored) as "fully supported" (IR 2a) based on results of fish contaminant monitoring (whole-fish carp samples) in 2002, 2004, 2005, 2006, 2008, 2009, 2010 and 2012.   The sources of data for this assessment include (1) information from Illinois EPA on water quality assessments for the Iowa/Illinois segment of the Upper Mississippi River, (2) results of routine chemical/physical water quality monitoring conducted at station M497.2B at Le Claire from 2002 through 2004 by IDNR staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at Bellevue, IA, and (3) results of fish contaminant monitoring from the following stations on the Upper Mississippi River monitored as part of the U.S.  EPA/DNR (RAFT) fish tissue monitoring program:  (1) near Buffalo (= Linwood), Iowa, in 2002, 2004 (trend (whole-fish) monitoring), and 2006 (status (fillet) monitoring) and (2) near Buffalo (Scott Co.) in 2004, 2006, 2008, and 2009, (3) near Linwood in 2006 and 2010 and (4) downriver from Muscatine in 2012 (status (fillet) monitoring).  Note: the location of the RAFT trend monitoring site downstream from Davenport in Pool 16 has changed over time between Linwood and Buffalo.  Data from either station can be used to characterize levels of fish contaminants downstream from Davenport.    

EXPLANATION:  The Class A1 (primary contact recreation) uses are considered “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 supported” based on results of ambient chemical/physical monitoring conducted from 2002 through 2004.   Results of monitoring by the LTRMP/Bellevue office near Le Claire (station M497.2B) showed no violations of Class B(WW1) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the 18 samples collected from January 2002 through September 2004 (note:  LTMRP monitoring has not been conducted at this station since 2004).   These data are older than five years and are thus less able to accurately characterize current water quality conditions.   Thus, the assessment of aquatic life uses which is based on these older data is of lower confidence compared to assessments based on more recent data.

The assessment of support of the fish consumption uses is based on results of U.S.  EPA/IDNR fish tissue (RAFT) monitoring at three locations: (1) in Pool 17 downstream from Muscatine (2) in Pool 16 near Linwood, and (3) in Pool 16 near Buffalo.   Results from all RAFT stations continue to show full support of fish consumption uses.  

Results of RAFT status (fillet) monitoring downstream from Muscatine (Pool 17) in 2005, 2006, and 2012 suggested “full support” of fish consumption uses.   In 2005, composite samples of common carp and white crappie fillets were analyzed; in 2006, composite samples of common carp and white bass fillets were analyzed, and in 2012, fillets of common carp and tissue plugs of white bass were analyzed.   The composite samples of fillets from common carp (all years), white crappie, and white bass all had low levels of contaminants.   Levels of primary contaminants in the composite sample of common carp fillets in 2005, 2006, and 2012 were as follows: mercury: 0.067, 0.131, and 0.046 ppm; total PCBs: 0.09, 0.147, and 0.09 ppm, and technical chlordane:  0.038, < 0.03, and <0.03 ppm.   Levels of primary contaminants in the composite sample of white crappie fillets collected in 2005 were as follows: mercury: 0.023 ppm; total PCBs: 0.09 ppm; and technical chlordane: < 0.03 ppm.   Levels of primary contaminants in the composite sample of white bass fillets collected in 2006 were as follows: mercury: 0.165 ppm; total PCBs: 0.09 ppm; and technical chlordane: < 0.03 ppm.   The average level of mercury in the 2012 tissue plugs from four white bass was 0.244 ppm.

Results of U.S.  EPA/IDNR fish contaminant (RAFT) status (fillet) monitoring near Linwood (Pool 16) in 2006 and 2010 also suggest “full support” of fish consumption uses.   In 2006, duplicate composite samples of common carp fillets were analyzed as was a sample of white bass fillets.   The composite samples of fillets from both samples of common carp had generally low levels of contaminants.   Levels of primary contaminants in the duplicate composite samples of common carp fillets were as follows: mercury: 0.232 and 0.179 ppm; total PCBs: 0.131 and 0.291 ppm, and technical chlordane:  0.054 and < 0.03 ppm.   Levels of primary contaminants in the composite sample of white bass fillets collected in Pool 16 in 2006 were as follows: mercury: 0.217 ppm; total PCBs: 0.108 ppm; and technical chlordane: < 0.03 ppm.   Results of whole fish common carp samples at the monitoring site near Linwood in 2010 also show low levels of primary contaminants.   Levels of primary contaminants in composite samples of whole-fish common carp were as follows: mercury: 0.0702 ppm; total PCBs: 0.129 ppm; technical chlordane: <0.03 ppm.      

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.    Data from past RAFT trend (whole fish) sampling (i.e., from the 2002 and 2004 RAFT sampling conducted downstream from Davenport), levels of contaminant were sufficiently high for concern and justify follow-up monitoring.   That is, the levels of at least one contaminant exceeded one or more advisory trigger levels, thus suggesting the need for additional (follow-up) monitoring to determine whether a consumption advisory should be issued.   The level of total PCBs in both the 2002 and 2004 samples of whole-fish common carp exceeds the 1 meal/week trigger level as defined in Iowa’s revised (2006) fish consumption advisory protocol.  

According to IDNR’s assessment methodology, the occurrence of levels of PCBs above an advisory trigger level in whole-fish samples—even in consecutive years—does not suggest impairment of the fish consumption uses but does suggest the need to conduct additional fish contaminant monitoring to determine contaminant levels in the edible portion of the fish.   The IDNR/IDPH advisory protocol states that two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory.   Thus, follow-up monitoring was conducted in 2006 in Pool 16 near Linwood.   This monitoring showed that levels of total PCBs in one of two samples of common carp fillets (0.291 ppm) exceeded the one meal/week advisory level; the level in the other sample (0.131 ppm) was below the advisory trigger level.   Additional monitoring will be conducted to better determine levels of PCBs in the edible portions (fillets) of fish in this river segment.  

Additional trend (whole fish) RAFT monitoring was conducted in 2008.   Results of this monitoring again showed low levels of mercury (0.2014 ppm) and chlordane (0.047 ppm).   Levels of total PCBs in the whole fish common carp samples again exceeded the advisory trigger level (0.273 ppm).  

Additional status (fillet) RAFT monitoring was conducted in 2009 near Buffalo.   Results of this monitoring showed low levels of primary contaminants in samples of common carp fillets and white bass fillets.   Levels of primary contaminants in the composite sample of common carp fillets were as follows: mercury: 0.0697 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm.    The level of mercury in the composite sample of white bass fillets was 0.218 ppm.   None of these levels were above the advisory trigger level, therefore indicating low levels of contaminants in the edible portion of fish.