[Note: A TMDL for pathogen indicators in this segment of the Volga River was prepared by DNR 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) indicated that the aquatic life uses of this segment are fully supporting and the aquatic life use impairment is removed.]

The Class A1 (primary contact recreation) uses are assessed (monitored) 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 32 samples collected during the recreational seasons of 2014 through 2016 at the DNR/SHL ambient station near Elkport were as follows: the 2014 geometric mean was 124 orgs/100 ml, the 2015 geometric mean was 154 orgs/100 ml, and the 2016 geometric mean was 416 orgs/100 ml. Two of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Twelve of the combined 32 samples (38 %) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and Iowa DNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary 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 "partially supported."

Results of chemical/physical water quality monitoring at the DNR/SHL ambient station near Elkport suggest “full support” of the aquatic life uses. Monitoring showed no violations of Class B(WW1) water quality criteria for 36 Ammonia samples (maximum = 0 mg/L), 36 Dissolved Oxygen samples (minimum = 7.2 mg/L), 36 pH samples (range = 7.7 to 8.4), 36 Temperature samples (maximum = 23.2°C), 36 Chloride samples (maximum = 19 mg/L), or 36 Sulfate samples (maximum = 26 mg/L) occurred during monitoring from January 2014 to December 2016. According to U.S. EPA guidelines for Section 305(b) water quality assessments (U.S. EPA 1997b, page 3-17), the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated. Thus, these results thus suggest “full support” of the Class B(WW1) aquatic life uses.

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.