Siewers Spring IA 01-UIA-6596
from mouth (NE1/4 SW1/4 S27 T98NR8W Winneshiek Co.) to headwaters (spring head) in SW1/4SW1/4 S27 T98N R8W Winneshiek Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 7/15/2019 7:45:50 AM
- Updated
- 7/15/2019 7:48:05 AM
The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as “not supported” due to violations of Iowa water quality criteria for indicator bacteria. The Class B(WW1) aquatic life uses are assessed as "fully supporting" based on results of chemical/physical water quality monitoring. The source of data for this assessment is the results of monitoring at Site 32 (STORET station 191910016) conducted as part of monitoring by the Northeast Iowa RC&D from April 2012 to October 2014.
The presumptive Class A1 uses are assessed (monitored) as “not supported" due to levels of indicator bacteria (E. coli) that exceed the Class A1 geometric mean criterion. The geometric means of indicator bacteria (E. coli) in the 21 samples collected during the recreational seasons of 2012, 2013, and 2014 at the Site 32 were 659, 626, and 1,309 orgs/100 ml, respectively. All three of these recreation season geometric means exceed Iowa’s Class A1 geometric mean criterion of 126 E. coli orgs/100 ml, thus indicating non-support of the presumptive Class A1 primary contact recreation uses. Seventeen of the 21 samples (81%) 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 DNR’s assessment/listing methodology, if a recreation season geometric mean is greater than the respective criterion (126 orgs/100 ml for Class A1, the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). In additional, the percentage of samples with levels of E. coli that exceeded Iowa single-sample maximum criteria indicate impairment of Class A1 uses at this monitoring site.
In terms of comparison to Iowa's Class A2 (secondary contact) criteria, the results of monitoring at Site 32 also suggest impairment. Two of the annual geometric means (2012 at 659 orgs/100 ml and 2014 at 1,309 orgs/100 ml) exceed the Class A2 geometric mean criterion of 630 orgs/100 ml. Four of the 21 samples (19%) 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 DNR’s assessment/listing methodology, if an annual geometric mean is greater than the Class A2 criterion (630 orgs/100 ml), the secondary contact recreation uses should be assessed as "impaired". Thus, if designated for Class A2 uses, this stream should be assessed as “not supported”.
Results of chemical/physical monitoring at Site 32 from 2012 to 2014 suggest "full support" of the presumptive Class B(WW1) aquatic life uses. None of the 14 samples analyzed from April 2012 to October 2014 violated the Class B(WW1) criteria for ammonia or temperature. None of the 14 samples collected violated the Class B(WW1) criteria for ammonia: all level of ammonia were reported as less than detection (0.05 mg/l) Only one of 14 samples (8%) violated the Class A1 & B(WW1) criterion for pH. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17), however, a violation frequency of less than 10% for conventional parameters such as pH does not suggest impairment of aquatic life uses. Based on DNR’s assessment methodology, these results suggest good water quality and "full support" of the presumptive Class B(WW1) aquatic life uses.