Assessment Comments
Assessment is based on: (1) results from the IDNR ambient monthly monitoring station near St. Joseph in Kossuth County (STORET station 10550001) from 2006 through 2008, and (2) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring near Algona in 2002 and 2008.
Basis for Assessment
[NOTE 1: Prior to the 2004 assessment, this segment was a single 19.628 mile segment identified as IA 04-EDM-0010_2. It was broken into two segments, now listed as IA 04-EDM-0010_2 and IA 04-EDM-0010_3 to reflect the location descriptions and classifications (HQR) as described in the Surface Water Classification. All previous assessments referring to the original 19.628 mile segment (previously known as IA 04-EDM-0010_2) can now be found listed in the documentation for segment IA 04-EDM-0010_3.]
[Note 2: 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 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), and due to the completion of a Use Attainability Analysis in 2007, 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 are assessed (monitored) as "not supported" due to high levels of indicator bacteria (E. coli). The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported" based on results of biological monitoring in 2002 and 2003 and on results of ambient water quality monitoring conducted from 2006-2008. Fish consumption uses remain assessed (evaluated) "fully supported" based on results of fish contaminant monitoring in 2002. The sources of data for this assessment include (1) results from the IDNR ambient monthly monitoring station near St. Joseph in Kossuth County (STORET station 10550001) from 2006 through 2008, (2) results of IDNR/UHL biological monitoring conducted in 2002 and 2003 as part of the DNR/UHL stream biocriteria and REMAP projects, and (3) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring near Algona in 2002 and 2008.
[Note 3: A TMDL for indicator bacteria (E. coli) was prepared by IDNR and approved by EPA in January 2009. Thus, the bacteria impairment for this segment was placed and remains in IR Category 4a (impaired; TMDL approved).]
EXPLANATION: The Class A1 uses are assessed (monitored) as "not supported" based on results of ambient monitoring for indicator bacteria (E. coli). The geometric mean level of indicator bacteria (E. coli) in the 24 samples collected (136 orgs/100ml) during the recreational seasons of 2006 through 2008 slightly exceeds the Iowa Class A1 water quality criterion of 126 orgs/100ml. Five of the 20 samples (25%) 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).
Results of IDNR/UHL ambient monitoring suggest relatively good water quality and “full support” of the Class B(WW1) uses. None of the approximately 33 samples collected during the 2006-2008 assessment period violated Class B(WW1) water quality criteria for dissolved oxygen, pH or ammonia-nitrogen. Neither of the two samples analyzed toxic metals violated state water quality criteria.
Fish consumption uses remain assessed (monitored) as “fully supported” based on results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring near Algona in 2002 and 2008. The composite samples of fillets from channel catfish and walleye in 2002 had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.069 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm. Levels of primary contaminants in the composite sample of walleye fillets were as follows: mercury: 0.154 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm. Follow-up sampling of walleye was conducted in 2008. The level of mercury in the composite sample of walleye fillets in 2008 was 0.14 ppm. 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 fish contaminant data generated from the 2008 RAFT sampling conducted at this river show that the levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.
