Assessment Comments
Assessment is based on results of (1) ambient monitoring conducted by Illinois EPA, 2003-06, (2) LTRMP ambient monitoring from 2002-04, and (3) EPA/IDNR fish contaminant (RAFT) monitoring in 2002 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 (evaluted) as "partially supporting" based on results of ambient monitoring provided for aluminum by Illinois EPA. Fish consumption uses remain assessed (monitored) as "fully supported." The sources of data used for this assessment are (1) results of monitoring conducted from February 24, 2003 to December 18, 2006 by the Illinois Environmental Protection Agency at station M-13 at Lock and Dam 11 at Dubuque (river mile 583), (2) results of routine chemical/physical water quality monitoring conducted at station M582.5B at the Lock and Dam 11 tailwater from January 2002 through September 2004 by IDNR staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at Bellevue, IA, and (3) results of U.S. EPA/DNR fish tissue (RAFT) monitoring in 2000 downstream from Guttenberg and in 2002 and 2006 near Dubuque (Mud Lake).
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. 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.” Water quality monitoring conducted by other agencies in this river segment (e.g., USGS and LTRMP) does not include analysis for indicator bacteria.
The Class B(WW1) (aquatic life) uses are assessed (evaluated) as “partially supported.” Results of water quality monitoring from LTRMP station M582.5B at the tailwater area of Lock and Dam 11 do not suggest water quality concerns with conventional parameters. Results of monitoring from 2002-04 at this station show no violations of Class B(WW1) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the 17 samples collected. (Note: LTMRP monitoring has not been conducted at this station since 2004.) Results of monitoring from Illinois EPA station M-13 at Lock and Dam 11, however, show that two of 15 samples analyzed for toxic metals during the 2003-2006 period exceeded Iowa’s Class B(WW1) chronic criterion for aluminum of 388 ug/l. Based on IDNR’s 2008 Section 303(d) listing methodology, however, these results do not suggest that significantly more than 10 percent of the samples exceed Iowa’s chronic criterion for aluminum and thus do not suggest an impairment of the Class B(WW1) aquatic life uses. Because more than one violation of the chronic criterion for aluminum occurred, this assessment segment will be placed in Category 2b of Iowa's 2008 Integrated Report and thus willl be added to Iowa's list of waters in need of further investigation.
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.
Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Dubuque 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 protective and 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 impairment of, fish consumption uses.
This scenario does not apply to the fish contaminant data generated from the 2006 RAFT sampling conducted in this assessment segment, levels of all contaminants were below advisory trigger levels. The composite samples of fillets from the 2006 RAFT sampling had low levels of contaminants. Levels of primary contaminants in the composite sample of common carp fillets were as follows: mercury: 0.091 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: 0.204 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. The levels of contaminants from the 2006 RAFT sampling do not exceed any of the new (2006) advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.
