Bloody Run IA 01-YEL-433
mouth (Clayton Co.) to west line of S22 T95N R4W Clayton Co.
- Assessment Cycle
- 2018
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 7/11/2019 7:06:32 AM
- Updated
- 8/30/2019 8:59:44 AM
The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as “partially supported” due to levels of indicator bacteria that slightly exceed the Class A1 single sample criterion. The presumptive Class A2 (secondary contact recreation) uses are assessed (monitored) as “fully supported”. The Class B(CW1) coldwater aquatic life uses are assessed (monitored) as "fully supported" based on (1) a summary of trout reproduction in Iowa streams and (2) results of ambient chemical/physical water quality monitoring conducted from 2014 through 2016. Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this coldwater stream. Sources of data for this assessment include (1) an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in January 2019 and (2) results of DNR physical/chemical water quality monitoring conducted at Bloody Run Creek from 2014 through 2016 at Site 1 (STORET station 10220003). Despite the very slight bacterial impairment, the results of chemical and bacterial monitoring over the 2014-16 period as well as the historical water quality monitoring data for this stream segment suggest that this segment of Bloody Run has exceptional water quality.
Despite very low levels of indicator bacteria during the 2014-2016 monitoring period, the Class A1 (primary contact recreation) uses remain 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 23 samples collected during the recreational seasons of 2014 through 2016 at Bloody Run Creek were as follows: the 2014 geometric mean was 119 orgs/100 ml, the 2015 geometric mean was 62 orgs/100 ml, and the 2016 geometric mean was 85 orgs/100 ml. None of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Five of the combined 23 samples (22%) 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). Also, if significantly more than 10% of the samples exceed Iowa’s single-sample maximum value of 235 E. coli orgs/100 ml, the Class A1 uses should be assessed as "partially supported." This assessment approach is based on U.S. EPA guidelines (see pgs 3-33 to 3-35 of U.S. EPA 1997b).All geometric means for the recreation seasons of 2014-2016 at Bloody Run Creek are below the geometric mean criterion. The percentage of violations of Iowa’s single-sample maximum criterion for E. coli (235 orgs/100 ml), however, is significantly greater than 10%. Thus, the primary contact recreation uses are assessed as "partially supported." The Class A2 (primary contact recreation) uses are assessed (monitored) as "fully supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 35 samples collected during the recreational seasons of 2014 through 2016 at Bloody Run Creek were as follows: the 2014 geometric mean was 47 orgs/100 ml, the 2015 geometric mean was 43 orgs/100 ml, and the 2016 geometric mean was 39 orgs/100 ml. None of the three recreation season geometric means exceeded the Class A2 geometric mean criterion of 126 orgs/100 ml. One of the combined 35 samples (3%) exceeded Iowa’s Class A2 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 none of the recreation seasons geometric means exceeded criteria for Class A1 uses, these uses are assessed as "fully supported." The Class B(CW1) coldwater aquatic life uses are assessed (monitored) as “fully supported.” This assessment is based in part on the updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in 2019. According to this summary, this reach of Bloody Run Creek is in the category of Iowa trout streams that have fairly consistent natural reproduction and are capable of maintaining a viable population of brown trout without any stocking (a Category I stream). The Class B(CW1) aquatic life uses were also assessed (monitored) as "fully supported" based on results of water quality monitoring at Site 1 on Bloody Run Creek from 2012 through 2014. None of the 36 monthly samples analyzed for dissolved oxygen, ammonia, temperature, pH, chloride and sulfate violated the respective Class B(CW1) aquatic life criteria. Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.