Coon Creek IA 01-UIA-265
mouth (NE 1/4 S3 T99N R7W Winneshiek Co.) to road crossing in S13 T98N R7W Winneshiek Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 5/8/2019 9:46:38 AM
- Updated
- 8/30/2019 7:32:58 AM
The presumptive Class A1 (primary contact recreation) uses and the presumptive Class A2 (secondary contact recreation) uses remain assessed (monitored) as “not supporting” due to levels of indicator bacteria that exceed state water quality criteria. The Class B(CW1) coldwater aquatic life uses are assessed (monitored) as “fully supporting” based on a summary of trout stream reproduction prepared by the DNR Fisheries Bureau and based on water quality monitoring from 2012 to 2014. Fish consumption uses remain “not assessed” due to the lack of fish contaminant monitoring in this stream segment. The sources of data for this assessment include (1) the results of water quality monitoring at Site 19 of the Upper Iowa River Watershed (UIRW) project (STORET No. NEIARCD 191910012) from April 2012 through October 2014 and (2) an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in January 2019.
The Class A1 (primary contact recreation) uses and the Class A2 (secondary contact recreation) uses remain both assessed as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 21 samples collected during the recreational seasons of 2012 through 2014 at UIRW Site 19 were as follows: the 2012 geometric mean was 932 orgs/100 ml, the 2013 geometric mean was 866 orgs/100 ml and the 2012 geometric mean was 816 orgs/100 ml. All three geometric means exceed the Class A1 criterion of 126 orgs/100 ml, and all three geometric means also exceed the Class A2 criterion of 630 orgs/100 ml. Sixteen of the 21 samples (76%) exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml; four of the 21 samples (24%) exceeded the Class A2 single-sample maximum criterion of 2,880 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and DNR’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). Monitoring from 2012 to 2014 at Upper Iowa River Watershed Site 19 also suggests full support of the Class B(CW1) aquatic life uses. This monitoring included analysis for ammonia, pH, and temperature. Of the 14 samples analyzed for ammonia, 12 samples contained less than the limit of detection (0.05 mg/l); the two detected samples contained 1.6 and 0.09 mg/l of ammonia. Although elevated, the concentration of 1.6 mg/l of ammonia is below the temperature/pH-dependent chronic ammonia criterion of 2.8 mg/l. Thus, all levels of ammonia were below any Class B(CW1) aquatic life criteria for ammonia. In addition, there were no violations of the Class B(CW1) criteria for pH or temperature in the 14 samples analyzed. These results do not suggest impairment of the Class B(CW1) aquatic life uses.
An updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in January 2019 suggests that the Class B(CW1) uses should be assessed as "fully supported". According to the updated summary, Coon Creek is in the group of Iowa coldwater streams that support natural reproduction of trout. Based on results of surveys by the DNR Fisheries Bureau, this stream is placed in the category of Iowa trout streams that exhibit consistent natural reproduction and maintain a wild population of brown trout without any stocking (Category I stream).
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream segment.