Assessment Comments
Assessment remains based on: (1) monthly monitoring conducted by IDNR and UHL at one location near Ionia (STORET station 11190001 (station 69)) from April 2001 through December 2004 as part of monitoring in support of TMDL development and (2) U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2003 and 2006.
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this river segment was designated only for Class B(WW) aquatic life uses, including fish consumption uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008, and due to the completion of a Use Attainability Analysis, this segment is also now designated for Class A1 (primary contact recreation) uses. This segment remains designated for warmwater aquatic life use (now termed Class B(WW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).]
SUMMARY: The Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" due to levels of indicator bacteria that violate state water quality criteria. The Class B(WW1) aquatic life uses remain assessed (monitored) as "fully supported" based on results TMDL-related water quality monitoring from 2002 through 2004. Fish consumption uses remain assessed (monitored) as “fully supported” based on results of fish contaminant monitoring in 2003 and 2006. The sources of data for this assessment are the results of (1) monthly monitoring conducted by IDNR and UHL at one location near Ionia (STORET station 11190001 (station 69)) from April 2001 through December 2004 as part of monitoring in support of TMDL development and (2) U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2003 and 2006. Note: USGS conducted monitoring at station 05458000 near Ionia in August 2009. Too few data were produced from this monitoring during the 2008-2010 assessment period (one sample) to be of use for assessment for purposes of either Section 305(b) reporting or Section 303(d) listing.
EXPLANATION: The Class A1 uses remain assessed as "not supported" based on results of ambient monitoring for indicator bacteria (E. coli). The overall geometric mean level of indicator bacteria (E. coli) in the 48 samples collected from April 2001 through (631 orgs/100ml) exceeded the Iowa Class A1 water quality criterion of 126 orgs/100ml. (Note: multiple samples were collected on selected sample dates during summer seasons; these multiple samples were averaged into a single daily value for purposes of developing this assessment.) Thirty-two of the 48 samples (67%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and according to IDNR’s assessment/listing methodology, if the geometric mean level of E. coli is greater than the state criterion of 126 orgs/100 ml., the primary contact recreation uses should be assessed as "not supported" (see pgs 3-33 to 3-35of U.S. EPA 1997b). Other approaches to summarizing the bacterial data for this station also suggest nonsupport of the Class A1 uses. For example, all yearly recreational season geometric means far exceed the Class A1 criterion of 126 orgs/100 ml: 2001: 8 samples with geometric mean of 269 orgs/100 ml; 2002: 16 samples with geometric mean of 644 orgs/100 ml; 2003: 10 samples with geometric mean of 530 orgs/100ml; 2004: 14 samples with geometric mean of 1,136 orgs/100 ml. Due to age of these data (greater than five years), the assessment type is changed from “monitored” (higher confidence assessment) to “evaluated” (lower confidence assessment).
The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supported” based on results of chemical/physical water quality monitoring conducted near Ionia in support of TMDL development from 2002 through 2004. The results of this monitoring show no violations of Class B(WW1) criteria for dissolved oxygen or pH in the 41 samples collected, or for ammonia-nitrogen in the 32 samples collected and analyzed. The parameter coverage at this station is somewhat limited (i.e., no analysis for toxic metals or pesticides). This assessment is consistent with previous assessments of aquatic life uses (“fully supported”) based on results of IDNR/UHL biocriteria sampling in 1995 and on results of IDNR stream use assessments in 1995 (see assessment developed for the 2000 cycle). Due to age of these data (greater than five years), the assessment type is changed from “monitored” (higher confidence assessment) to “evaluated” (lower confidence assessment).
Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Chickasaw Park in 2003 and 2006. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes. Fish contaminant data generated from the 2003 RAFT sampling conducted in this assessment segment showed that levels of contaminants were sufficiently high for concern and thus justified follow-up monitoring. The levels of at least one contaminant from past monitoring at this station approached one or more advisory trigger levels, thus suggesting the need for additional (follow-up) monitoring to determine whether a consumption advisory should be issued.
The 2003 composite samples of fillets from common carp and smallmouth bass had generally low levels of contaminants. Levels of primary contaminants in the composite sample of carp fillets were as follows: mercury: 0.097 ppm; total PCBs: 0.09 ppm; and technical chlordane: < 0.03 ppm. Levels of primary contaminants in the composite sample of smallmouth bass fillets were as follows: mercury: 0.225 ppm; total PCBs: 0.09 ppm; and technical chlordane: < 0.03 ppm. Although assessed as “fully supported” for this reporting cycle, the level of at least one contaminant approached one or more advisory trigger levels: the level of mercury in the sample of smallmouth bass fillets (0.225 ppm) approached the one meal per week trigger level of 0.30 ppm. According to the IDNR/IDPH advisory protocol, this single result neither warranted issuance of an advisory nor indicated impairment of the fish consumption uses: two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory.
Follow-up monitoring was conducted in 2006 to better determine (1) levels of mercury in the edible portions (fillets) of fish in this river segment and (2) whether a one-meal-per-week consumption advisory needs to be issued. The results of the follow-up monitoring in 2006 show a level of mercury in the composite sample of smallmouth bass fillets (0.239 ppm) similar to that seen in the 2003 sample (0.225 ppm). Taken together, the results of the 2003 and 2006 RAFT samplings suggest somewhat elevated levels of mercury in the smallmouth bass in this assessment segment. Levels of mercury, however, remain lower than the advisory trigger level of 0.3 ppm and thus do not justify issuance of a consumption advisory.
