Unnamed Tributary to West Fork Cedar River IA 02-WFC-2075
from mouth (SE1/4 S28 T93N R19W Franklin Co.) to headwaters in NE1/4 S7 T92N R19W Franklin Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 7/26/2019 7:51:52 AM
- Updated
- 7/26/2019 7:51:52 AM
The presumptive Class A1 (primary contact recreation) are remain "not assessed" due to a lack of water quality information upon which to make an assessment. The presumptive Class B(WW1) (aquatic life) uses are assessed as "partially supported" based on results of a fish kill investigation in August 2007. This assessment was changed from IR Category 3b to IR 5b for the 2012 IR cycle due to the severity and extent of this fish kill. This fish kill was historically used to assess the next upstream segment - https://programs.iowadnr.gov/adbnet/Segments/2079. However, for the current cycle, the impairment was removed from segment 2079 and applied to this segment.
The presumptive Class B(WW1) (aquatic life) uses are assessed (evaluated) as "partially supported" due to a fish kill in 2007. The fish kill occurred on or before August 17, 2007 and affected 1.7 miles of the stream; no cause was identified for the kill. An estimated 18,780 fish were killed. No details of the types of fish killed were provided. The estimated value of the fish was $3,134.85. According to DNR’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 was not identified during the DNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.” Such assessments, although suitable for Section 305(b) reporting, lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (IR Category 5). Due, however, to the extremely large number of fish killed (~18,000), the length of the kill (1.7 miles), and the lack of naturally occurring environmental extremes during summer 2007 that would have contributed to this kill (e.g., low stream flow and/or high water temperatures), some type of pollutant cause is suspected.