Assessment Comments

Assessment is based on: (1) results from the IDNR ambient monthly monitoring station from 2006 through 2008 near St. Joseph in Kossuth County (STORET station 10550001), (2) results of IDNR/UHL biological monitoring conducted in 2001-2003 and 2008, and (3) 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 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 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 (evaluated) as "partially supported" based on results of biological monitoring in 2001-2003 and 2008 and on results of chemical/physical monitoring from 2006-2008.   Fish consumption uses remain assessed (evaluated) 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 2001-2003 and 2008, and (3) results of U.S.  EPA/IDNR fish contaminant (RAFT) monitoring near Algona in July 2002 and 2008.  

[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).  

This evaluated biological assessment was based on data collected in 2001-2003 and 2008 as part of the IDNR/UHL stream ambient biological and REMAP sampling projects.   A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biological sampling data.   The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2003 FIBI score was 48 (fair) and the 2001-2003 and 2008 BMIBI scores were 62, 65, 58 (good) and 49 (fair).   The aquatic life use support was assessed (evaluated) as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2004.   The non-riffle habitat FIBI BIC for this ecoregion is 32 and the BMIBI BIC for this ecoregion is 62.   This segment passed the FIBI BIC 1/1 times in 2003 and passed the BMIBI BIC 2/4 times in the last 10 years.   This assessment is considered evaluated because the drainage area (977 and 927 mi2) above the sampling sites was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria.   Even though this site passed the FIBI and failed the BMIBI BIC, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it doesn’t fall in the calibrated watershed size.

This aquatic life assessment is also now considered "evaluated" based on a change in the 2010 IDNR assessment methodology.   IDNR now requires a segment have two or more biological samples collected from the segment in multiple years between 2004 and 2008 to be considered “monitored”.     This segment had multiple BMIBI samples collected in the previous 10 years (1999-2008); however, the samples were not collected during 2004-2008.   According to IDNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report).   IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).  

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 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.