Assessment Comments
Assessment is based on fish kill investigations in July and October 2006.
Basis for Assessment
[Note: Prior to the current (2008) Section 305(b) cycle, this stream segment was designated 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 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), this segment is now presumptively designated for Class A1 (primary contact recreation) uses. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current (2008) assessment, 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 are "not assessed" due to a lack of water quality information upon which to base an assessment. The Class B(WW-2) aquatic life uses are assessed (monitored) as "not supported" due to fish kills in July and October of 2006.
EXPLANATION: The first fish kill occurred on or before July 18, 2006 and was attributed to runoff from an open feedlot on a small tributary of Prairie Creek. Rainfall from the previous night washed manure and corn glucose from the feedlot into the tributary to Prairie Creek. Approximately 108,882 dead fish including carp, white suckers, smallmouth bass, and minnows were found up to 14 miles downstream of the tributary. The estimated value of the dead fish was $18306.78. At the time of this assessment there are no records that IDNR has sought/received restitution for this fish kill.
The second fish kill occurred on or before October 20, 2006 and was caused by hog manure that entered the creek when a coupler on an umbilical line failed while it was draining a hog facility. The kill occurred southeast of Keystone and affected 3.4 miles of the stream. Approximately 22,809 fish were killed. No information on types of fish was provided. The estimated value of the dead fish was $8484.01. At the time of this assessment there are no records that IDNR has sought/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 (2005-2007) 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 will be placed in Category 5b of Iowa’s 2008 Integrated Report.
