Assessment Comments

Assessment is based on results of (1) IDNR/UHL ambient monthly monitoring near St. Joseph from 2000-02, (2) IDNR/UHL biological (biocriteria) sampling in 2002, and (3) U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2002.

Basis for Assessment

[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 refering to the original segment (IA 04-EDM-0010_2) can now be found listed in the documentation for segment IA 04-EDM-0010_3.]

SUMMARY:  The Class B(WW) aquatic life uses are assessed (monitored) as "fully supported / threatened" (minor impacts) based on results of biological monitoring in 2002.   Results of monthly ambient chemcial/physical water quality monitoring during the assessment period show no violations of Class B(WW) water quality criteria.   Fish consumption uses are assessed (monitored) "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), (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.

EXPLANATION:  The Class B(WW) uses are assessed as "fully supported / threatened" based on results of biological monitoring.   Results of ambient chemical/physical monitoring at the St.  Joseph station during the 2000-2002 assessment period, however, show no violations of Class B(WW) (aquatic life) water quality criteria in the 36 samples analyzed for dissolved oxygen, pH, and ammonia or  in the nine samples analyzed for pesticides.   These results suggest that the aquatic life uses of this river segment are "fully supported."  

Results of biological monitoring, however, suggest a threat to the full support of these uses.   This assessment is based on data collected in 2002 as part of the DNR/UHL stream biocriteria project.   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/threatened (=FS/T), 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.

Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.  EPA/IDNR fish contaminant (RAFT) monitoring in 2002.   Composite samples of fillets from channel catfish and walleye had very low levels of contaminants.   Neither sample contained levels of contaminants that approached even one-half the respective FDA action levels or IDNR levels of concern.   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.