Assessment Comments
Assessment is based on results of (1) 2006 assessment information from Illinois EPA, (2) ambient monitoring by Illinois EPA near Lock and Dam 15 from 2001-03, and (3) fish contaminant monitoring conducted by EPA/IDNR in 2001.
Basis for Assessment
SUMMARY: 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 are assessed (monitored) as "not supported" due to violations of state water quality criteria for aluminum. The Class C (drinking water) uses remain assessed (monitored) as "not supported" due to violations of state water quality criteria for arsenic. Fish consumption uses are assessed (monitored) as "fully supported/threatened" (impaired) based on results of fish contaminant monitoring in 2001 and on the history of high levels of PCBs in fish from the Iowa side of Pool 15 of the Upper Mississippi River. 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 2001 through September 2003 by the Illinois Environmental Protection Agency at station M-02 at Lock and Dam 15 at Arsenal Island at river mile 482.9 and (3) results of fish tissue monitoring in Pool 15 conducted for the U.S. EPA/IDNR (RAFT) fish tissue monitoring program.
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 were 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 showed that six of 12 samples analyzed for toxic metals during the 2001-2003 period exceeded Iowa’s Class B(WW) chronic criterion for aluminum of 388 ug/l. According to U.S. EPA guidelines for Section 305(b) water quality assessments (U.S. EPA 1997b, page 3-18), more than one violation of a water quality criterion for a toxic pollutant in an abundant data set (at least 10 samples over at three-year period) indicates an impairment of aquatic life uses. Monitoring results for other toxic parameters and for conventional parameters show no violations of Class B(WW) criteria during the 2001-2003 period.
The Class C (drinking water) uses, however, 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 2.6 mg/l in the 12 samples) and Class C toxic metals 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 all of the 12 samples collected, with a maximum level of 2.3 ppb, a mean level of 1.2 ppb, and a median level of 1.0 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. The mean level of arsenic during the biennial period (1.2 ppb) is nearly seven times the human health criterion of 0.18 ppb; thus, "nonsupport" of drinking water uses is indicated.
Fish consumption uses were assessed (monitored) as “fully supported / threatened” (impaired) based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Davenport in 2001 and on the history of high levels of PCBs in fish from the Iowa side of Pool 15. 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 applies 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 now exceed 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 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, exceed 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 are assessed as “fully supported/threatened” (impaired). 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 will be conducted in 2006 to determine whether an advisory is again needed for this waterbody.
