Assessment Comments

Assessment is based on: (1) results from the IDNR ambient monthly monitoring station from 2004 through 2006 near St. Joseph in Kossuth County (STORET station 10550001), (2) results of IDNR/UHL biological monitoring conducted in 2002 as part of the IDNR/UHL stream biocriteria project, and (3) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring near Algona in July 2002.

Basis for Assessment

[Note 1:  Prior to the 2004 assessment, this segment was referred to 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 as described in the Surface Water Classification.  All previous assessments referring to the original segment (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 current (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 remain assessed (monitored) as "fully supported" based on results of biological monitoring in 2002 and on results of chemical/physical monitoring from 2004-2006.   Fish consumption uses remain assessed (monitored) as "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 from 2004 through 2006 near St.  Joseph in Kossuth County (STORET station 10550001), (2) results of IDNR/UHL biological monitoring conducted in 2002 as part of the IDNR/UHL stream biocriteria project, and (3) results of U.S.  EPA/IDNR fish contaminant (RAFT) monitoring near Algona in July 2002.

[Note 3:  A TMDL for indicator bacteria (E.   coli) was prepared by IDNR and approved by EPA in Janary 2009.    Thus, the bacteria impairment for this segment is placed 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).   Due to recent changes in Iowa’s Water Quality Standards, Iowa’s assessment methodology for indicator bacteria has changed.   Prior to 2003, the Iowa WQ Standards contained a high-flow exemption for the Class A criterion for indicator bacteria (fecal coliforms) designed to protect primary contact recreation uses:  the water quality criterion for fecal coliform bacteria (200 orgs/100 ml) did not apply "when the waters [were] materially affected by surface runoff."  Due to a change in the Standards in July 2003, E.  coli is now the indicator bacterium, and the high flow exemption was eliminated and replaced with language stating that the Class A criteria for E.  coli apply when Class A1, A2, or A3 uses “can reasonably be expected to occur.”  Because the IDNR Technical Advisory Committee on WQ Standards could not agree on what flow conditions would define periods when uses would not be reasonably expected to occur, all monitoring data generated for E.  coli during the assessment period, regardless of flow conditions during sample collection, will be considered for determining support of Class A uses for purposes of Section 305(b) assessments and Section 303(d) listings.  

The geometric mean level of indicator bacteria (E.  coli) in the 24 samples collected (157 orgs/100ml) during the recreational seasons of 2004 through 2006 slightly exceeds the Iowa Class A1 water quality criterion of 126 orgs/100ml.   Eleven of the 24 samples (46%) 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).  

The Class B(WW1) uses remain assessed (monitored) as "fully supported" based, in part, on results of IDNR/UHL biological monitoring in 2002.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data.   The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species that were collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (F-IBI) and a benthic macroinvertebrate index (BM-IBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2002 BM-IBI score was 66 (good).  The aquatic life use support was assessed (evaluated) as fully supported (=FS), based on a comparison of the BM-IBI score with biological assessment criteria established for previous Section 305(b) reports.   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001.

Results of chemical/physical water quality monitoring also suggest full support of the Class B(WW1) aquatic life uses.   None of the approximately 35 samples collected during the 2004-2006 assessment period violated Class B(WW1) water quality criteria for pH or ammonia-nitrogen.   None of the approximately 7 samples analyzed for pesticides or the 10 samples analyzed for toxic metals violated state water quality criteria.   One of the 34 samples analyzed for dissolved oxygen, however, violated the Class B(WW1) criterion of 5.0 mg/l (this sample contained a dissolved concentration of 3.7 mg/l).   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 nonetheless suggest "full support" of aquatic life uses.   Thus, the percentage of violations of the dissolved oxygen criterion at this station (3%) does not suggest an impairment of aquatic life uses in this stream segment.  

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.   The composite samples of fillets from channel catfish and walleye 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.

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 compatible with the various protocols used by adjacent states, the Iowa Department of Public Health, 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 either a threat to, or impairment of, fish consumption uses.   This scenario, however, does not apply to the fish contaminant data generated from the 2002 RAFT sampling conducted in this assessment segment:  the levels of contaminants do not exceed any of the new (2006) advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.