East Fork Des Moines River IA 04-EDM-971

Assessment Comments

Assessment is based on results of (1) IDNR/UHL biological (REMAP) monitoring in 2003 and biocriteria monitoring in 2001 and 2002, (2) IDNR/UHL ambient monitoring from 2002-2004 and (3) EPA/IDNR fish contaminant (RAFT) monitoring in 2002.

Basis for Assessment

[NOTE:  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.]

SUMMARY:  The Class B(WW) 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 2002-2004.   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) from 2002 through 2004, (2) results of IDNR/UHL biological monitoring conducted in 2002 and 2003 as part of the DNR/UHL stream biocriteria and REMPA projects, and (3) results of U.S.  EPA/IDNR fish contaminant (RAFT) monitoring near Algona in 2002.

EXPLANATION:  This evaluated biological assessment was based on data collected in 2001, 2002 and 2003 as part of the DNR/UHL stream biocriteria/REMAP projects.   A series of biological metrics that 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 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 BMIBI score was 58 (good).   The 2002 BMIBI score was 66 (good) and the 2001 BMIBI score was 62 (good).   The BMIBI average was 62.   The aquatic life use support was assessed (evaluated) as Fully Supporting (= FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The FIBI BIC for this ecoregion is 32 and the BMIBI BIC for this ecoregion is 62.   This assessment is considered evaluated because the drainage area (925 mi2) above this sampling site was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria.   Even though this site passed both the FIBI and BMIBI BICs, 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.  

Results of IDNR/UHL ambient monitoring also suggest relatively good water quality and “full support” of the Class B(WW) uses.   None of the approximately 35 samples collected during the 2002-2004 assessment period violated Class B(WW) 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(WW) 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 percentages 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 were 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.