Assessment Comments
Assessment is based on (1) 2006 assessment information from the Illinois EPA and (2) results of fish tissue (RAFT) monitoring at two locations: (1) near Muscatine in 2002 and (2) near Buffalo (Scott Co.) in 2002 and 2004.
Basis for Assessment
The Class A (primary contact recreation) uses are assessed (monitored) as “not supported” based on the impairment identified by the Illinois EPA due to high levels of indicator bacteria. The Class B(WW) aquatic life uses remain "not assessed" due to the lack of information upon which to base an assessment. Fish consumption uses are assessed as "fully supported" based on results of fish contaminant monitoring (whole-fish carp samples) in 2002 and 2004. 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 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 and 2004 (trend (whole-fish) monitoring) and (2) near Muscatine (Pool 17) in 2002 (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 A (primary contact recreation) uses are assessed as “not supported” based on the impairment of primary contact recreation uses identified for this segment of the Upper Mississippi River by the Illinois EPA for the 2006 Section 303(d) listing cycle. The Illinois EPA identified an impairment of primary contact recreation uses in this river segment due to high levels of indicator bacteria (fecal coliforms). This assessment was developed as result of interstate consultation on Section 303(d) listing conducted through the Upper Mississippi River Basin Association’s “Water Quality Task Force”. The Class B(WW) aquatic life uses remain "not assessed" due to lack of monitoring information for this river reach.
Results of U.S.EPA/IDNR fish contaminant (RAFT) status (fillet) monitoring near Muscatine in 2002 suggest “full support” of fish consumption uses. The composite samples of fillets from channel catfish and flathead catfish had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.055 ppm; total PCBs: 0.123 ppm; and technical chlordane: < 0.03 ppm. Levels of primary contaminants in the composite sample of flathead catfish fillets were as follows: mercury: 0.044 ppm; total PCBs: 0.09 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. 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. Although this scenario does not apply to the fish contaminant data generated from the 2002 and 2004 RAFT sampling conducted downstream from Davenport, levels of contaminant are sufficiently high for concern and justify follow-up monitoring. That is, the levels of at least one contaminant now exceeds one or more advisory trigger levels, thus suggesting the need for additional (follow-up) monitoring to determine whether a consumption advisory should be issued. I
The 2002 and 2004 whole-fish samples of common carp had generally low levels of the primary contaminants: the 2002 sample contained the following: mercury: 0.133 ppm; total PCBs: 0.295 ppm; and technical chlordane: 0.069 ppm. The 2004 sample contained the following: mercury: 0.095 ppm; total PCBs: 0.25 ppm; and technical chlordane: < 0.03 ppm. While results from the 2002 and 2004 sampling show that levels of chlordane and mercury are well below levels of concern, 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. And, according to the IDNR/IDPH advisory protocol, the monitoring results for the whole-fish samples collected downriver from Davenport do not warrant issuance of an advisory but do indicate the need to conduct additional monitoring to determine contaminant levels in the edible portions of fish from this river segment. Thus, follow-up monitoring will be conducted in 2006 to better determine (1) levels of PCBs in the edible portions (fillets) of fish in this river segment and (2) whether a consumption advisory for PCBs needs to be issued.
