[Note:  A TMDL for pathogen indicators in this segment of the Volga River was prepared by IDNR and approved by EPA in 2006.  Because the primary Section 303(d) impairment identified for the 2006 assessment/listing cycle (indicator bacteria) was addressed by the TMDL, this waterbody was moved from IR Category 5a from the 2004 assessment/listing cycle to IR Category 4a (impaired; TMDL approved) for the 2006 cycle.  Subsequent biological monitoring indicated a biological impairment not covered by the TMDL; thus, this waterbody was placed in Category 5b-v of the 2010 Integrated Reporting cycle.  However, recent biological sampling data (2006, 2012-2014) indicates that the aquatic life uses of this segment are fully supporting and the aquatic life use impairment is removed.]  

EXPLANATION:  The Class A1 (primary contact recreation) are assessed as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria.  The geometric means of indicator bacteria (E. coli) in the 48 samples collected during the recreational seasons of 2012 through 2014 at the IDNR/SHL ambient station near Elkport were as follows:  the 2012 geometric mean was 174 orgs/100 ml, the 2013 geometric mean was 205 orgs/100 ml, and the 2014 geometric mean was 124 orgs/100 ml.  The 2012 and 2013 geometric means slightly exceed the Class A1 criterion of 126 orgs/100 ml; the 2014 geometric mean is slightly below the Class A1 criterion.  Thirteen of the 48 samples (27%) exceeded the Class A1 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 a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.”  This river reach has a history of high levels of indicator bacteria, with assessments of either "partial support" or "nonsupport" of the primary contact recreation uses made since the 1992 Section 305(b) report. 

[Note:  the above geometric means of E. coli at station 10220002 are based on raw data for the 48 samples collected during the recreation seasons of 2012 through 2014 (16 samples collected during each recreation season).  If serially correlated samples in these data (i.e., bacteria samples collected within one to three days) are averaged, the 2012 geometric mean of the ten independent samples becomes 242 orgs/100 ml, the 2013 geometric mean of the 12 independent samples becomes 230, and the 2014 geometric mean of the ten independent samples becomes 131 orgs/100 ml.  Nine of the 32 samples (28%) exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml.  Thus, whether raw data or averaged data are used, the results of monitoring at this station suggest “non-support” of the presumptive Class A1 (primary contact recreation) uses.]  

Results of IDNR TMDL bacterial monitoring on the Volga River at Littleport (Site 32) also suggest impairment of the Class A1 uses due to geometric means of indicator bacteria that exceed the Class A1 criterion.  The geometric means of indicator bacteria (E. coli) in the 15 samples collected during the recreational seasons of 2012 through 2014 at the this station were as follows:  the 2012 geometric mean of seven samples was 282 orgs/100 ml, the 2013 geometric mean was 429 orgs/100 ml, and the 2014 geometric mean of eight samples was 108 orgs/100 ml.  Similar to the results from the IDNR ambient monitoring station, two of the three geometric means slightly exceed the Class A1 criterion of 126 orgs/100 ml.  Nine of the 24 samples (38%) exceeded the Class A1 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 a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.” 

The results of IDNR ambient water quality monitoring from 2012 through 2014 suggest "full support" of the Class B(WW1) uses due to the lack of violations of state water quality criteria for pH (78 combined samples), dissolved oxygen (84 combined samples), ammonia-nitrogen (52 combined samples), temperature (84 combined samples), and chloride/sulfate (68 combined samples) during this three-year period. 

In agreement with the recent water quality results, the aquatic life use assessment based on IDNR/SHL biological sampling conducted in 2006, 2012, 2013, and 2014 as part of IDNR/SHL stream sampling projects, suggest “full support” of the Class B(WW1) aquatic life uses.  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 (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 2006 FIBI score was 78 (excellent).  The 2012, 2013 and 2014 BMIBI scores were 75, 67 and 72 (all good).  The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports.  The FIBI BIC for this ecoregion is 52 and the BMIBI BIC for this ecoregion is 61.  This segment passed the FIBI BIC 1/1 times in 2006 and passed the BMIBI BIC 3/3 times in the last five years.  The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008.  This aquatic life use assessment is considered "monitored" because there were two or more BMIBI samples collected in multiple years over a recent five-year period. 

Monitoring data collected from the IDNR/SHL ambient fixed station near Elkport (10220002) during the 2010-2014 data assessment period were sufficient to complete a Nutrient Impact Assessment (NIA). Data analysis methods and screening benchmark values for nutrient stressor and response parameters described in the IDNR’s 2016 NIA methodology were used to examine for nutrient impacts often associated with low biotic index scores and violations of dissolved oxygen (DO) criteria. Nutrient stressor: The median concentration of total phosphorus (TP) was 0.10 mg/L among samples collected during the June 15- October 15 index period. The TP benchmark (0.10 mg/L) was exceeded in 9 of 20 samples. The percentage exceeding (45%) was less than (passing) the 50% threshold; however, the statistical analysis confidence level (< 90%) was not high. Nutrient response parameters: The median concentration of algal chlorophyll A suspended in water (WCHLA) was 7 ug/L. The WCHLA benchmark (20 ug/L) was exceeded in 1 of 20 samples. The percentage exceeding (5%) was less than (passing) the 50% threshold with high statistical confidence (> 90%). The median rating of filamentous algae coverage (FLMA) on hard substrates was 0 (Absent). The FLMA benchmark (3; 50%-75%)  was exceeded in 0 of 8 observations. The percentage exceeding (0%) was less than (passing) the 50% threshold with high statistical confidence (>90%). 

The results of this “evaluated” assessment indicate the presence of reasonably low levels of the nutrient stressor parameter (TP) and low levels of the nutrient response parameters (WCHLA and FLMA). This combination of results is interpreted as representing a low risk of aquatic life use impairment due to nutrient enrichment. Continuous monitoring data were not available to examine for violations of DO criteria; however, the benthic macroinvertebrate index (BMIBI) results described suggest full attainment of aquatic life uses. Based on the assessed risk level, the stream segment is considered a low priority for follow-up nutrient impact monitoring.

The fish consumption uses remain "not assessed" due to the lack of recent fish tissue monitoring in this river reach.