Assessment Comments
Assessment is based on results of (1) 2010 assessment information from Illinois EPA, (2) ambient monitoring by Illinois EPA near Lock and Dam 15 from 2006-08, (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 2010 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 and cadmium. 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. 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 21, 2006 to December 19, 2008 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. 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 are assessed (monitored) as “not supported” due to violations of Iowa’s chronic criterion for aluminum and cadmium in water. Results of water quality monitoring from Illinois EPA station M-02 from 2006-2008 showed that 13 of 17 samples (76%) analyzed for toxic metals exceeded Iowa’s Class B(WW1) chronic criterion for aluminum of 87 ug/l. Three of the 17 samples violated the Class B(WW1) acute criterion of 750 ug/l for aluminum. Based on IDNR’s 2010 Section 303(d) listing methodology, these results indicate impairment of the Class B(WW1) aquatic life uses due to (1) significantly more than 10 percent of the samples exceeding Iowa’s chronic criterion for a toxic parameter and (2) more than one violation of an acute criterion for a toxic parameter occurred during a three-year period. [Note: the chronic/acute criteria for aluminum used for the 2008 assessment were 388 and 4,539 ug/l respectively; these criteria were changed in the Iowa Water Quality Standards to 87 and 750 ug/l, respectively in 2007. Iowa’s aquatic life criteria for metals are expressed as “total recoverable.”]
In addition, five of the 19 samples analyzed for cadmium exceeded the respective hardness-dependent Class B(WW1) chronic criteria (criteria ranged from 0.39 to 0.49 ug/l). According to IDNR’s assessment methodology, the frequency of violations of the chronic criteria for cadmium is significantly greater than 10% and thus suggests non-support of the Class B(WW1) aquatic life uses. [Note: the chronic/acute criteria for cadmium used for the 2008 assessment/listing cycle were 15 and 75 ug/l respectively; these criteria were changed in the Iowa Water Quality Standards to hardness-dependent criteria of 0.27 and 2.13 ug/l (based on a hardness of 100 mg/l as Ca CO3) respectively, in 2007. The sample-specific hardness values were used to identify violations of these criteria at station M-02.] One of 17 samples (6%) violated the Class B(WW1) criterion for dissolved oxygen. The sample collected on August 15, 2007 contained 4.7 mg/l of dissolved oxygen, thus violating the Class B(WW1) criterion of 5 mg/. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17), however, a violation frequency of less than 10 % for conventional parameters such as dissolved oxygen does not suggest impairment of aquatic life uses.
Monitoring results for other toxic parameters and for conventional parameters show no violations of Class B(WW1) criteria during the 2006-2008 period. Results of monitoring by the LTRMP/Bellevue office near Le Claire 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).
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. Violations of the Class C human health criterion for arsenic (0.18 ppb) occurred in eight of the 19 samples collected during the 2006-08 period (42% violation), with a maximum level of 9.9 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. However, the samples with detectable levels of arsenic were too few and the method detection levels were too high to allow calculation of a meaningful summary statistic (e.g., mean) for arsenic concentrations at station M-02. Thus, the assessment of nonsupport of the designated drinking water uses is based on the history of levels of arsenic at this monitoring station that exceed the HH criterion. Levels of nitrate (maximum value of 2.7 mg/l) and levels of Class C toxic metals in the 12 samples collected from 2006-2008 at Station M-02 were well below their respective MCLs and Class C human health criteria. 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.
[Note: In March 2010, U.S. EPA Region 7 provided for public comment a draft TMDL for the arsenic impairment of the drinking water uses of this assessment segment as identified by IDNR (see http://www.epa.gov/region07/water/pdf/mississippi_river_ia_draft_tmdl.pdf). The draft TMDL identified the following potential sources of arsenic in the Upper Mississippi River that could potentially have caused this impairment: natural sources in soil and subsurface geology, airborne and surface source ash from coal fired power plants, point source discharges, MS4 regulated stormwater, groundwater, and non-regulated stormwater runoff from nonpoint sources such as pesticides application and wood preservatives containing arsenic. The pollutant source assessment conducted for the TMDL concluded that, although minor contributions of arsenic from select point sources were identified, natural background (soil and groundwater) are the primary source of arsenic loading to this segment of the Upper Mississippi River. Because the natural background concentrations of arsenic already exceeded the water quality criterion upon which the impairment was based, any addition of arsenic to a waste stream would therefore elevate the current exceedance of the water quality criterion. Therefore, the draft TMDL concluded that “the sum of waste loads for these segments is a WLA of zero pounds per day.” U.S. EPA’s response to public comments noted that EPA intended to establish this TMDL to meet the milestones of the 2001 Consent Decree, Sailors, el al. v. EPA, Consolidated Case No. C98-134MJM, December 17, 2001. Comments received on the draft TMDL, however, suggested that this arsenic impairment was not part of the 2001 consent decree. Following a thorough record review, EPA concluded that the arsenic impairment was, in fact, not covered by the consent decree and that the draft arsenic TMDL would not be finalized at this time (see http://www.epa.gov/region07/water/pdf/public_notice/ms_river_response_commen_total_arsenic.pdf). Because this TMDL was not finalized, the arsenic impairment of the designated drinking water uses for this assessment segment remains in Category 5 of Iowa’s Integrated Report and remains on Iowa’s Section 303(d) list of impaired waters.]
Fish consumption uses remain 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. 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 had 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 were assessed (monitored) as “fully supported” for the previous (2008) Section 303(d) listing cycle. Based on these results, the fish consumption uses remain assessed (monitored) as “fully supported” for the 2010 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.
