Assessment Comments
Assessment is based on results of (1) 2012 assessment information from Illinois EPA, (2) ambient monitoring by Illinois EPA near Lock and Dam 15 from 2008-2010, (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 considered “not assessed” due to the lack of monitoring information upon which to base an assessment. The Class B(WW1) aquatic life uses are assessed (monitored) as "not supported" (IR Category 5a) due to violations of state water quality criteria for aluminum and cadmium. The Class C (drinking water) uses are assessed (monitored) as "not supported" (IR Category 5a) due to violations of state water quality criteria for arsenic. Fish consumption uses are assessed (evaluated) as "partially supported” (IR Category 3b) due to violations of state Human Health criteria (fish + water) for dieldrin. Results of fish contaminant monitoring in 2001 and 2006, however, suggest “full support” of fish consumption uses and suggest that levels of dieldrin are below levels of detection in bottom feeding fish in this river segment. Sources of data for this assessment include (1) information from Illinois EPA on 2012 water quality assessments for the Iowa/Illinois segment of the Upper Mississippi River, (2) results of ambient water quality monitoring conducted from May 7, 2008 to November 16, 2010 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 considered “not assessed” due to the lack of information upon which to base an assessment. Although ambient monitoring is conducted in this river segment by the Illinois EPA, the resulting data are for fecal coliform bacteria. These data are not applicable to Iowa’s water quality standard for E. coli to protect the designated Class A1 primary contact recreation uses.
Similar to the previous assessments, the Class B(WW1) aquatic life uses are assessed (monitored) for the current (2012) cycle as “not supported” (IR Category 5a) based on results of Illinois EPA monitoring at station M-02 near Rock Island, IL, from 2008 through 2010 that show violations of Iowa’s aquatic life criteria for aluminum and cadmium. None of the 22 samples analyzed for dissolved aluminum exceeded the chronic aquatic life criterion (87 ug/l) for aluminum, but 20 of the 22 samples analyzed for total aluminum exceeded this criterion (minimum = 40 ug/l; maximum = 3,190 ug/l total aluminum) [Iowa’s aquatic life criteria for metals are expressed as “total recoverable” in the Iowa Water Quality Standards]. In addition, ten of the 22 samples analyzed for total aluminum exceeded the acute aquatic life criterion (750 ug/l). For cadmium, four of seven samples analyzed as dissolved cadmium exceeded the respective hardness-dependent chronic criteria (criteria ranged from 0.39 to 0.57 ug/l); 12 of the 24 samples analyzed for total cadmium exceeded these criterion. Based on Iowa DNR’s assessment/listing methodology, more than one violation of a chronic or acute water quality criterion for a toxic parameter over a three-year period suggests impairment of aquatic life uses. Thus, the frequency of violations of the aquatic life criteria for aluminum (20 violations) and chromium (12 violations) suggests that the Class B(WW1) aquatic life uses of this assessment segment should be assessed as “not supported” and thus this assessment segment is placed in IR Category 5a.
For chromium, copper, lead, nickel, and zinc, none of the approximately 24 samples analyzed for these metals exceed the respective chronic aquatic life criteria. One of the 25 samples analyzed for dissolved oxygen slightly violated Iowa’s Class B(WW1) criterion of 5.0 mg/l: the sample collected on June 23, 2009, contained 4.93 mg/l of dissolved oxygen. According to Iowa DNR’s assessment/listing methodology, however, a violation frequency of less than 10% for conventional parameters such as pH and dissolved oxygen does not suggest impairment of aquatic life uses. Monitoring data from Illinois EPA station M-02 from 2008-2010 showed no violations of Class B(WW1) water quality criteria for pH or ammonia-nitrogen in the 25 samples analyzed.
[Note on change in listing methodology regarding toxics: 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 for the 2008 listing cycle. Prior to the 2008 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 collected 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. This methodology was also used for Iowa’s 2010 listing cycle. For the current (2012) cycle, however, EPA Region 7 informed its states that this “10%” approach to identifying impairments due to toxics would no longer be acceptable. Rather, states were to consider the occurrence of more than one violation of a water quality criterion (chronic or acute) for a toxic parameter over a three-year period as indicating Section 303(d) impairment.]
Class C (drinking water) uses continue to be assessed as "not supported" due to violations of Iowa’s human health water quality criterion for arsenic. Of the 24 samples analyzed for total arsenic from 2008-2010 at Station M-02, all 11 samples with detectable levels of arsenic (range from 1.3 to 32.7 ug/l) exceeded Iowa’s Human Health (fish+water) criterion of 0.18 ug/l. Of the 24 samples analyzed for dissolved arsenic, all 14 samples with detectable levels (range from 1.2 to 15.7 ug/l) also exceeded Iowa’s HH criterion. Detection levels for arsenic were relatively high during a portion of the 2008-2010 period, with method detection levels reported as 4.45 ug/l; this detection level is approximately 25 times greater than Iowa’s Human Health criterion of 0.18 ug/l. Beginning in July 2009, however, the Illinois EPA detection level for arsenic was lowered to 0.94 ug/l (approximately five times greater than Iowa’s human health criterion). According to Iowa DNR’s assessment/listing methodology, if the mean level of a toxic metal or pesticide is greater than an MCL or human health criterion, impairment ("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 remains based on the history of levels of arsenic at this monitoring station that frequently exceed the HH criterion and the tendency for all samples with detectable levels of arsenic to far exceed this criterion.
[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, et 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.]
Monitoring results for other parameters do not show violations of Class C criteria. Maximum and average levels of nitrate (maximum value of 2.9 mg/l and mean of 1.8 mg/l in 24 samples), atrazine (maximum value of 0.39 ug/l in 21 samples), and Class C toxic metals at station M-02 were well below their respective MCLs and Class C human health criteria during the 2008-2010 period.
The Human Health designated use (including the fish consumption use) is assessed (evaluated) as “partially supporting” (IR Category 3b-potentially impaired). Two of the 21 samples analyzed by ILEPA for dieldrin at station M-02 during the 2008-2010 period (the only detectable levels reported) exceeded the Iowa human health-fish (HH-fish) criterion of 0.00054 ug/l; the detected levels of dieldrin were 0.0015 and 0.0021 ug/l. According to IDNR’s assessment/listing methodology, if the mean level of a toxic metal or pesticide is greater than its respective human health criterion, impairment ("nonsupport") of the Human Health use is indicated. However, the samples with detectable levels of dieldrin were too few (two) and the method detection level (0.0014 ug/l) was too high (2.5 times the HH criterion for dieldrin) to allow calculation of a meaningful summary statistic (i.e., mean) for dieldrin at station M-02.
Results of fish contaminant sampling in this river segment conducted as part of the U.S. EPA/IDNR RAFT program have shown that levels of dieldrin in the composite samples of fillets from common carp and channel catfish analyzed for the 2001 RAFT were below the levels of detection (<0.003 and <0.0052 mg/kg) (the 2006 RAFT samples were not analyzed for dieldrin). Although Iowa does not have a fish consumption advisory trigger level for dieldrin, the very low dieldrin levels seen in the 2001 RAFT samples from Davenport (i.e., < 5 ppb) is far below the Iowa’s previous advisory trigger of 300 ppb of dieldrin (i.e., the U.S. FDA action level for dieldrin). Levels of dieldrin in Iowa fish have declined significantly since the early and mid-1980s when levels of 300 ppb to 500 ppb were not uncommon. Due to the low levels of dieldrin in fish tissue samples from this river segment, and due to the low frequency with which violations of the human health (fish + water) dieldrin criterion occurs, this assessment is considered appropriate for Iowa’s IR Category 3b (potential impairment). IR Category 3b waters will be added to Iowa’s list of waters in need of further investigation.
Despite the potential impairment of the Human Health/Fish Consumption uses suggested by levels of dieldrin in water samples, the results of EPA/DNR fish tissue (RAFT) monitoring near Davenport in 2001 and 2006 suggest that fish consumption uses should be assessed as "fully supported". 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 showed a much lower level of total PCBs in common carp (0.09 ppm vs. 0.476 ppm in 2001) and indicated that a consumption advisory was not justified for this river segment. Thus, the fish consumption uses were assessed (monitored) as “fully supported” for the previous (2008 and 2010) Section 303(d) listing cycles.
