Assessment Comments
Assessment is based on: (1) an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006 and (2) results of IDNR physical/chemical water quality monitoring conducted at Bloody Run Creek from January 2006 through December 2008 at Site 1 (STORET station 10220003).
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(CW) aquatic life 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 presumptively designated for Class A1 (primary contact recreation) and Class A2 (secondary contact recreation) uses. This segment remains designated for coldwater aquatic life use (now termed Class B(CW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption) uses.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as “not supported” due to high levels of indicator bacteria. 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 2006 through 2008. 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 May 2006 and (2) results of IDNR physical/chemical water quality monitoring conducted at Bloody Run Creek from January 2006 through December 2008 at Site 1 (STORET station 10220003).
EXPLANATION: The Class A1 (primary contact recreation) uses are assessed (monitored) as “not supported.” The geometric mean of E. coli in the 21 samples collected at Bloody Run site 1 during the recreational seasons of 2006 through 2008 was 133 orgs/100 ml. This geometric mean slightly exceeds the Class A1 criterion of 126 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean of E. coli is greater than the applicable state criterion, the primary contact recreation uses should be assessed as "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).
The Class A2 (secondary contact recreation) uses, however, are assessed (monitored) as “fully supported.” The geometric mean of the 32 samples collected during calendar years of 2006 through 2008 was also 133 orgs/100 ml. This geometric mean is far below the Class A2 criterion of 630 orgs/100 ml. Only one of the 32 samples exceeded Iowa’s Class A2 single-sample maximum criterion of 2,880 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean of E. coli is below the applicable state criterion, the primary contact recreation uses should be assessed as "fully supported" (see pgs 3-33 to 3-35of U.S. EPA 1997b).
The Class B(CW1) coldwater aquatic life uses are also assessed 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 May 2006. 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 for the target trout species without any stocking. 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 2006 through 2008. None of the 32 samples analyzed for dissolved oxygen, ammonia, or pH violated the respective Class B(CW1) aquatic life criteria. Neither of the two samples collected during this period violated chronic criteria for toxic metals.
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.
