Assessment Comments

Assessment is based on results of (1) results monthly water quality monitoring from January 2004 through December 2006 at the IDNR ambient station (STORET station 10220001) located at the County Road C43 bridge south of Garber approximately 1 mile downstream from confluence with the Volga River, (2) results of water quality monitoring conducted at Garber by USGS from March 2006 to December 2006, (3) results of routine water quality monitoring conducted at station TK04.8M from 2002 through 2004 by IDNR staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at Bellevue, IA, (4) results of U.S. EPA/IDNR fish tissue (RAFT) monitoring in 2000 near Garber, and (5) biological monitoring conducted in 2002 by the IDNR Fisheries Bureau and in 2003 by IDNR/UHL for the Iowa REMAP project.

Basis for Assessment

[Note:  Prior to the current (2008) Section 305(b) cycle, this stream 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), 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 were assessed (monitored) as "not supported" due to levels of indicator bacteria that exceeded state water quality criteria.   The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported" based on results of (1) ambient chemical/physical water quality monitoring from 2004-06 conducted by IDNR/UHL, LTRMP, and USGS and (2) biological monitoring conducted by the IDNR Fisheries Bureau in 2002 and by IDNR/UHL in 2003.   Fish consumption uses remain assessed (monitored) as "fully supported" based on results of fish contaminant monitoring in 2000.   Sources of data for this assessment include (1) results monthly water quality monitoring from January 2004 through December 2006 at the IDNR ambient station (STORET station 10220001) located at the County Road C43 bridge south of Garber approximately 1 mile downstream from confluence with the Volga River, (2) results of water quality monitoring conducted at Garber by USGS from March 2006 to December 2006, (3) results of routine water quality monitoring conducted at station TK04.8M from 2002 through 2004 by IDNR staff of the Upper Mississippi River Long-Term Resource Monitoring Program (LTRMP) at Bellevue, IA, (4) results of U.S.  EPA/IDNR fish tissue (RAFT) monitoring in 2000 near Garber, and (5) biological monitoring conducted in 2002 by the IDNR Fisheries Bureau and in 2003 by IDNR/UHL for the Iowa REMAP project.  

EXPLANATION:  The Class A1 (primary contact recreation) uses were assessed (monitored) as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria.   The Class A1 use designation was added to this river segment by the state of Iowa in March 2006; this change in use classification was approved by U.S.  EPA in February 2008.  

The geometric mean of indicator bacteria (E.  coli) in the 24 samples collected during the recreational seasons of 2004 through 2006 at the IDNR ambient monitoring station near Garber exceeded the Iowa water quality criterion to protect primary contact recreation uses.   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 A1 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, this 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 of E.  coli bacteria in the 24 samples from the IDNR ambient monitoring station near Garber was 181 orgs/100 ml, thus exceeding Iowa’s geometric mean criterion of 126 orgs/100 ml; seven samples (29%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml.   According to U.S.  EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S.  EPA 1997b).  

The Class B(WW1) aquatic life uses were assessed (monitored) as "fully supported" based on results of ambient monthly monitoring from (1) the IDNR/UHL ambient station south of Garber from 2004 through 2006 (2) the USGS station near Garber from 2004 through 2006, and (3) from the LTRMP station near the mouth of the Turkey River in 2004-06.   In addition, the results of biological monitoring in 2002 and 2003 also suggest “full support” of the Class B(WW) uses.  

Monitoring at the IDNR and LTRMP stations showed no violations of Class B(WW1) water quality criteria for conventional pollutants or ammonia in the 36 samples analyzed at the IDNR station and in the 43 samples analyzed at the LTRMP station.   In addition, none of the 10 sampled analyzed for common pesticides at the IDNR/UHL station violated their respective Class B(WW1) criteria.   Of the ten samples analyzed for toxic metals, only one sample violated a Class B(WW1) criterion:  one of the ten samples analyzed for lead exceeded the Class B(WW1) criterion of 30 ug/l.   This violation occurred on July 6, 2004; the level of lead in the sample was 60 ug/l.   According to U.S.  EPA guidelines for Section 305(b) water quality assessments (U.S.  EPA 1997b, page 3-18), however, one violation of a water quality criterion for a toxic pollutant in an abundant data set (at least 10 samples over at three-year period) does not indicate an impairment of aquatic life uses.   None of the approximately 35 samples collected by USGS from March 2004 through December 2006 showed violations of Class B(WW11) criteria for DO, pH, ammonia, or pesticides; also, neither of the two samples analyzed for toxic metals exceeded Class B(WW1) criteria.

Results of biological monitoring conducted by the IDNR Fisheries Bureau in 2002 and conducted by IDNR/UHL in 2003 suggest that the Class B(WW1) aquatic life uses should be assessed (evaluated) as “fully supported”.   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 REMAP FIBI score was 75 (excellent) and the BMIBI score was 53 (fair).   The 2002 Fisheries FIBI was 39 (fair).   The FIBI average was 57.   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 52 and the BMIBI BIC for this ecoregion is 61.   This assessment is considered evaluated because the drainage area (1482 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.

Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Garber in 2000.   The composite samples of fillets from channel catfish and smallmouth bass had low levels of contaminants.   Levels of primary contaminants in the composite sample of channel catfish fillets were as follows:  chlordane: < 0.03 ppm; dieldrin:  0.0094; total PCBs:  0.195 ppm; mercury:  0.034 ppm.   Levels of primary contaminants in the composite sample of smallmouth bass fillets were as follows:  chlordane: < 0.03 ppm; total PCBs:  <0.10 ppm; mercury:  0.084 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 2000 RAFT sampling conducted in the Turkey River near Garber:  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.