Assessment Comments
Assessment remains based on results of a fish kill investigation in 2004.
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was classified only for Class B(LR) aquatic life uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008, this segment is now presumptively designated for Class A1 (primary contact recreation) uses. According to the Iowa Water Quality Standards, all perennial rivers and streams and all intermittent streams with perennial pools that are not specifically listed in the Iowa surface water classification are designated as Class A1. Thus, for the current (2012) assessment, perennial flow is presumed, and the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses remain "not assessed" due to a lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed (monitored) as "partially supported" based on the results of a fish kill investigation in November 2004.
EXPLANATION: The kill occurred on or before November 2, 2004. Because of high water and extremely turbid conditions, a count of dead fish was not made through the complete kill area, however it was estimated that 1,314 fish were killed. The kill occurred north of Lidderdale, beginning at a tile approx. 300 yards upstream from bridge on east side of Sec 4, T85N R34W Carroll Co. The suspected cause of the kill was runoff from a cattle feedlots. The estimated value of the fish was $149.98. At the time of this assessment there is no information as to whether the DNR sought or received restitution for this fish kill.
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. Thus, this assessment segment was placed, and remains in, Category 5b of Iowa’s Integrated Report.
