West Rat Creek IA 06-BSR-6609
from mouth (T98N R43W Sec22) to headwaters (T99N R42W Sec20 SW SE)
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 12/14/2016 3:47:01 PM
- Updated
- 12/14/2016 3:47:01 PM
The presumptive Class A1 (primary contact recreation) uses are "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The presumptive Class B(WW1) aquatic life uses are assessed (monitored) as "partially supported" (IR 5b) based on results of an IDNR investigation of a pollutant-caused fish kill in August 2014. This is a new impairment for this previously unassessed stream segment.
This fish kill occurred approximately 4.5 miles NE of Matlock, Iowa, on or before August 20, 2014. The kill was attributed aerial spraying of pesticide. No estimate of the number of fish killed was provided in the Iowa DNR fish kill investigation report. The kill affected approximately one-half mile of stream. Based on this information, presumptive Class B(WW1) aquatic life uses are assessed as “partially supporting” and are placed on Iowa’s Section 303(d) list of impaired waters. According to IDNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired.” If a cause of the kill is identified, and the cause is either known, or suspected, to be a “pollutant”, the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing. Fish kills attributed to a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b. The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources.