Mississippi River IA 01-NEM-61

Assessment Comments

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

Basis for Assessment

SUMMARY:  The Class A1 (primary contact recreation) uses are assessed (monitored) as “fully supported” based on the 2010 assessment developed by the Illinois EPA.   The Class B(WW1) aquatic life uses remain assessed as “fully supported” based on results of chemical/physical water quality monitoring conducted from 2002-2004.   Fish consumption uses are assessed as "fully supported" based on results of fish contaminant monitoring (whole-fish carp samples) in 2002, 2004, 2005, 2006, and 2008.   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 two 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 Muscatine (Pool 17) in 2002 and 2004 (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 assessed (monitored) as “fully supported” based on the results of ambient monitoring for indicator bacteria as conducted by the Illinois EPA.   This assessment was developed as result of interstate consultation on Section 303(d) listing conducted in May 2010 through the Upper Mississippi River Basin Association’s “Water Quality Task Force”.  

The Class B(WW1) aquatic life uses remain assessed (monitored) 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).  

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

Results of RAFT status (fillet) monitoring downstream from Muscatine (Pool 17) in 2005 and 2006 suggest “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.   The composite samples of fillets from common carp (both 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 and 2006 were as follows: mercury: 0.067 and 0.131 ppm; total PCBs: 0.09 and 0.147 ppm, and technical chlordane:  0.038 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.

Results of U.S.  EPA/IDNR fish contaminant (RAFT) status (fillet) monitoring near Linwood (Pool 16) in 2006 also suggest “full support” of fish consumption uses.   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.  

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.  

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).  

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.