Willow Creek IA 06-FLO-1829

This fish kill occurred on or before September 11, 2003; the kill was attributed to animal waste from an open feedlot (animal type unknown). An estimated 101 fish were killed; except for one white sucker, the fish killed were reported to be “minnows”. No estimated value of the fish killed was provided. An estimated 3 miles of this stream was affected by the kill. No responsible party was identified. The location point for this kill is the SW ¼ of the SE ¼ of Section 19, T94N, R43W, Sioux County near Granville. According to the DNR investigation, this stream has many feedlots along its banks. A heavy rain (5-6 inches) occurred on the day of kill, and this rain event likely flooded the stream with farm and feedlot runoff. Recent drought conditions and low stream flows likely made the fish susceptible to any kind of pollution that might have washed in from the recent rainfall.

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 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. For previous assessment/listing cycles, DNR had considered fish kill-impaired (IR 5b) waters with no subsequent kills in the three year subsequent to the kill as appropriate for de-listing and for movement to IR categories 2b or 3b (i.e., Iowa’s list of waters in need of further investigation). Due, however, to EPA uncertainty regarding the full recovery of the aquatic life following the kill, any existing fish kill (5b) impairment will remain in IR Category 5b until more recent monitoring has shown full recovery of the aquatic communities affected by the kill. Thus, this assessment segment will remain in Category 5b of Iowa’s Integrated Report.