Assessment Comments
Assessment is based on results of (1) 2008 assessment information from Illinois EPA, (2) ambient monitoring by Illinois EPA near Lock and Dam 15 from 2003-06, (3) LTRMP ambient WQ monitoring from 2002-04 near Le Claire, and (4) fish contaminant monitoring conducted by EPA/IDNR in 2001 and 2006.
Basis for Assessment
SUMMARY: The Class A1 (primary contact recreation) uses are assessed (monitored) as “fully supported” based on the 2008 assessment developed by the Illinois EPA. The Class B(WW1) aquatic life uses are assessed (monitored) as "not supported" due to violations of state water quality criteria for aluminum. The Class C (drinking water) uses are assessed (monitored) as "not supported" due to violations of state water quality criteria for arsenic. Fish consumption uses are assessed (monitored) as "fully supported” based on results of fish contaminant monitoring in 2006. Based on results of recent monitoring, the 2006 Section 303(d) impairments for indicator bacteria and for PCBs in fish tissue are proposed for de-listing for the 2008 cycle. 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 ambient water quality monitoring conducted from February 25, 2003 to December 19, 2006 by the Illinois Environmental Protection Agency at station M-02 at Lock and Dam 15 at Arsenal Island at river mile 482.9, (3) 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 (4) results of fish tissue monitoring in Pool 15 conducted for the U.S. EPA/IDNR (RAFT) fish tissue monitoring program in 2001 and 2006.
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 from 2003-2006. Although assessed as “impaired” by Illinois EPA for the 2006 listing cycle, recent monitoring has shown that levels of indicator bacteria in this segment of the Upper Mississippi River no longer suggest impairment of primary contact uses. This assessment was developed as result of interstate consultation on Section 303(d) listing conducted on June 10, 2008 through the Upper Mississippi River Basin Association’s “Water Quality Task Force.”
The Class B(WW1) (aquatic life) uses are assessed (monitored) as “not supported” due to violations of Iowa’s chronic criterion for aluminum in water. Results of water quality monitoring from Illinois station M-02 at Lock and Dam 15 from 2003-2006 showed that five of 15 samples analyzed for toxic metals exceeded Iowa’s Class B(WW1) chronic criterion for aluminum of 388 ug/l. Based on IDNR’s 2008 Section 303(d) listing methodology, these results suggest that significantly more than 10 percent of the samples exceed Iowa’s chronic criterion for aluminum and thus suggest an impairment of the Class B(WW1) aquatic life uses. Monitoring results for other toxic parameters and for conventional parameters show no violations of Class B(WW1) criteria during the 2003-2006 period. Results of monitoring by the LTRMP/Bellevue office near Le Claire show 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).
Note: Based on consultation with other Region 7 states and U.S. EPA Region 7 staff in 2007, IDNR's methodology for assessing impairments due to violations of chronic criteria for toxic parameters was changed. Prior to the 2008 listing cycle, IDNR followed a U.S. EPA recommendation (U.S. EPA 1997b, page 3-18) that more than one violation of a water quality criterion for a toxic pollutant in an abundant data set indicates an impairment of aquatic life uses. Because no state in Region 7 collects ambient data with the frequency necessary to accurately identify compliance with a chronic criterion (i.e., to allow calculation of short-term (4-day or 30-day) averages), Region 7 states concluded that another assessment approach (e.g., the 10% rule) was more appropriate. Thus, for the 2008 listing cycle, IDNR identified aquatic life impairments for toxic parameters when significantly more than 10% of the samples exceeded a chronic criterion.
The Class C (drinking water) uses are assessed (monitored) as "not supported" due to violations of the human health water quality criterion for arsenic at Illinois EPA station M-02. Levels of nitrate (maximum value of 2.7 mg/l) and levels of Class C toxic metals in the 12 samples collected from 2003-2006 were well below their respective MCLs and Class C human health criteria. Violations of the Class C human health criterion for arsenic (0.18 ppb), however, occurred in ten of the 14 samples collected during this period (71% violation), with a maximum level of 2.8 ppb, a mean level of 1.4 ppb, and a median level of 1.3 ppb. According to IDNR guidelines for Section 305(b) assessments, if the mean level of a toxic metal or pesticide is greater than an MCL or human health criterion, "nonsupport" of the drinking water use is indicated. Results of water quality monitoring at Le Claire by the LTRMP/Bellevue office show no violations of Class C water quality criteria for nitrate in the 18 samples collected from January 2002 through September 2004 (maximum nitrate = 7.9 mg/l; median = 1.9 mg/l). 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 at Davenport in 2006. 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 (IDPH), 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 applied to the fish contaminant data generated from the 2001 RAFT sampling conducted in this assessment segment. Although previously assessed as “fully supported,” the levels of contaminants in the 2001 sampling exceeded one or more advisory trigger levels, thus suggesting a potential need to issue a consumption advisory. Iowa DNR’s assessment methodology states that if elevated levels of contaminants suggest the potential for a consumption advisory, the fish consumption uses should be assessed as “fully supported/threatened.”
The 2001 composite samples of fillets from common carp and channel catfish had generally low levels of contaminants. The levels of total PCBs in both samples, however, exceeded the IDNR/IDPH trigger level of 0.20 ppm for a one meal per week consumption advisory: the level of PCBs in the sample of common carp fillets was 0.476 ppm and in the sample of channel catfish fillets was 0.544 ppm. According to the IDNR/IDPH advisory protocol, two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory. Because, however, the levels of contaminants in the 2001 sample were more than twice the 1 meal/week trigger level, and due to the history of elevated levels of PCBs in this river reach, the fish consumption uses were assessed as “fully supported/threatened” (impaired) for the 2006 Section 303(d) listing cycle. A consumption advisory existed for the Iowa side of Pool 15 from 1989 through 2000 due to levels of PCBs in common carp and carpsuckers (Carpiodes spp.) that exceeded the FDA action level of 2.0 ppm. Additional monitoring was conducted in 2006 to determine whether a fish consumption advisory was again needed for this waterbody.
Results of the 2006 RAFT sampling at Davenport, however, showed much lower levels of contaminants than did the 2001 sampling. Levels of primary contaminants in the composite sample of common carp fillets were as follows: mercury: 0.09 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.184 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. These results show a much lower level of total PCBs in common carp (0.09 ppm vs. 0.476 in 2001) and indicate that a consumption advisory is not justified at this time for this river segment. Thus, the fish consumption uses are assessed (monitored) as “fully supported” for the 2008 Section 303(d) listing cycle. Additional monitoring will be conducted in this river segment as part of future RAFT monitoring to continue to track levels of PCBs in fish.
