East Fork Des Moines River IA 04-EDM-970
mouth (Humboldt Co.) to Hwy 169 at Devine Access in S26 T94N R29W Kossuth Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trend
- Unknown
- Created
- 8/2/2019 8:46:36 AM
- Updated
- 8/2/2019 8:49:44 AM
The Class A1 (primary contact recreation) uses are assessed as "partially supported" due to high levels of indicator bacteria (E. coli). The Class B(WW1) aquatic life are assessed as “fully supporting” based on results of water quality monitoring from 2012 through 2014. Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river reach. The sources of data for this assessment are the results from the DNR ambient monthly monitoring station near St. Joseph in Kossuth County (STORET station 10550001) from 2012 through 2014.
Note: A TMDL for indicator bacteria (E. coli) was prepared by DNR and approved by EPA in January 2009. Thus, the 2006 bacteria impairment was moved from IR Category 5a to Category 4a (impaired; TMDL approved) for the 2008 cycle. This impairment remains in Category 4a of Iowa’s Integrated Report.
The Class A1 uses are assessed (monitored) as "partially supported" based on results of monitoring for indicator bacteria (E. coli). The geometric means of indicator bacteria (E. coli) in the 24 samples collected during the recreational seasons of 2012 through 2014 at DNR station 10550001 near St. Joseph were as follows: the 2012 geometric mean was 64 orgs/100 ml, the 2013 geometric mean was 394 orgs/100 ml, and the 2014 geometric mean was 231 orgs/100 ml. The 2013 and 2014 geometric means slightly exceed the Class A1 criterion of 126 orgs/100 ml; the 2012 geometric mean is well-below the Class A1 criterion. Ten of the 24 samples (42%) exceeded the 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 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). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired” (partially supported).
Results of DNR/SHL ambient monitoring from 2012-2014 suggest relatively good water quality and “full support” of the Class B(WW1) uses. None of the 36 samples collected during the 2012-2014 assessment period at the DNR/SHL ambient monitoring station (10550001) violated Class B(WW1) water quality criteria for pH, ammonia-nitrogen, temperature, chloride, or sulfate. One of the 36 samples (3%) had a level of dissolved oxygen (4.4 mg/l) that violated the Class B(WW1) criterion of 5.0 mg/l. According to U.S. EPA guidelines for Section 305(b) reporting (U.S. EPA 1997b: page 3-17), a violation frequency for conventional parameters such as dissolved oxygen of less than 10% does not suggest an impairment of aquatic life uses. Thus, the results of chemical/physical water quality monitoring from 2012-2014 suggest “full support” of the Class B(WW1) aquatic life uses.