Chariton River IA 05-CHA-1307
from the Iowa/Missouri state line to the Highway 2 crossing in S27 T69N R17W Appanoose Co.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 9/26/2016 2:53:22 PM
- Updated
- 1/18/2017 10:28:05 AM
The Class A1 (primary contact recreation) uses are assessed (monitored) as “partially supporting" (IR 5p) based on the identification of a bacterial impairment in the adjacent downstream segment in Missouri. This impairment was identified using Iowa DNR data for indicator bacteria. This is a new impairment for this segment of the Chariton River. The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supporting” (IR 2a) based on results of chemical/physical monitoring in 2004. Fish consumption uses remain “not assessed” (IR 3a) due to lack of fish contaminant monitoring data upon which to base an assessment. The source of data for this assessment remains the results of USGS chemical/physical water quality monitoring near Moulton from March 2004 through September 2004.
The presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" (IR 5p) due to identification of an impairment for indicator bacteria (E. coli) in the adjacent downstream segment by the Missouri Department of Natural Resources. This bacterial impairment covers the entire length of the Chariton River in Missouri. The bacterial impairment for the upper portion of the Chariton River in Missouri was based on data for E. coli from the Iowa DNR monitoring station downstream from Rathbun Dam (STORET station 10040001). Thus, identification of an IR Category 5 impairment for the Iowa segment of the river adjacent to Missouri seems justified. A TMDL for the bacterial impairment on the Missouri portion of the Chariton River was approved by EPA in December 2010. The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supported" based on results of water quality monitoring by the U.S. Geological Survey near Moulton in 2004. No violations of state water quality criteria occurred in the seven samples analyzed for dissolved oxygen, pH, ammonia, chlorpyrifos, DDE, and dieldrin. Although these results indicate “full support” of the aquatic life uses of this river segment, the number of samples is relatively low and does not meet IDNR guidelines for developing a “monitored” (i.e., higher confidence) assessment. Thus, the assessment type is considered “evaluated” (lower confidence). Also, because these data are now more than five years old, and because as data age beyond five years they are less able to represent current water quality conditions, the assessment type is considered “evaluated” (lower confidence assessment) rather than “monitored” (a higher confidence assessment). The fish consumption uses remain “not assessed” due to the lack of information upon which to base an assessment.