Assessment Comments
Assessment is based on results of (1) results monthly water quality monitoring from January 2006 through August 2008 at the IDNR ambient station (STORET station 10220001) located at the County Road C43 bridge south of Garber, (2) results of water quality monitoring conducted at Garber by USGS from January 2006 to December 2008, (3) results of LTRMP monitoring at station TK04.8M from 2002 through 2004, (4) results of U.S. EPA/IDNR fish tissue (RAFT) monitoring in 2007 and 2008 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 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 are 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 (evaluted) as "partially supported" based on results of 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 2007 and 2008. Sources of data for this assessment include (1) results monthly water quality monitoring from January 2006 through August 2008 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 January 2006 to December 2008, (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 2007 and 2008 near Garber, and (5) biological monitoring conducted in 2002 by the IDNR Fisheries Bureau and in 2003 conducted 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 21 samples collected during the recreational seasons of 2006 through 2008 at the IDNR ambient monitoring station near Garber exceeded the Iowa water quality criterion to protect primary contact recreation uses. The geometric mean of E. coli bacteria in the 21 samples from this station was 444 orgs/100 ml, thus exceeding Iowa’s geometric mean criterion of 126 orgs/100 ml; 11 samples (52%) 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). Note: monitoring for bacterial indicators was not conducted at the USGS monitoring station at Garber.
The Class B(WW1) aquatic life uses are assessed (evaluated) as "partially supported" based on results of ambient monthly monitoring from (1) the IDNR/UHL ambient station south of Garber from 2006 through 2008 (2) the USGS station near Garber from 2006 through 2008, and (3) from the LTRMP station near the mouth of the Turkey River in 2002-04. In addition, the results of IDNR biological monitoring in 2002 and 2003 also suggest “full support” of the Class B(WW) uses.
Monitoring at the IDNR, USGS, and LTRMP stations showed no violations of Class B(WW1) water quality criteria for conventional pollutants or ammonia in the 32 samples analyzed at the IDNR station, the 34 samples analyzed at the USGS station, and in the 43 samples analyzed at the LTRMP station. In addition, none of the samples analyzed for common pesticides at these monitoring stations (IDNR/UHL, 2 samples; USGS 1 sample) violated the respective Class B(WW1) criteria. No violations of Class B(WW1) criteria for toxic metals occurred in the combined (IDNR/USGS) three samples analyzed
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 “partially 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 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 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 biological assessment is considered “evaluated” because the drainage area (1553 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 the one out of two samples failed to meet the FIBI BIC and the 2003 sample passed 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.
Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Garber in 2007 and 2008. The composite samples of fillets from channel catfish and smallmouth bass in 2007 had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: chlordane: <0.03 ppm; total PCBs: 0.09 ppm; mercury: 0.09 ppm. The level of mercury in the composite sample of smallmouth bass fillets was 0.514 ppm. The level of mercury in the sample of smallmouth bass is above the IDPH/IDNR advisory trigger level (0.30 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. According to IDNR's methodology two consecutive samples with levels above the advisory trigger level are necessary to issue a fish consumption advisory. Follow-up sampling was conducted in 2008 to better determine the levels of mercury in smallmouth bass and determine whether an advisory is justified for this river segment. The 2008 sampling showed the level of mercury in the composite sample of smallmouth bass fillets (0.269 ppm) was below the advisory trigger level. Therefore an advisory at this river segment is not justified and the fish consumption uses remain assessed (monitored) as "fully supported."
