Assessment Comments
Assessment remains based on results of an IDNR investigation of a fish kill south of Clarion in 2001.
Basis for Assessment
[Note: For the 2002 report, the previous waterbody segment for White Fox Creek (IA 04-UDM-0220-0), which extended 17 miles from its mouth to confluence with an unnamed tributary in Wright County, was split into two subsegments: (1) mouth to the Hamilton / Wright county line (IA 04-UDM-0220-1) and (2) Hamilton / Wright county line to confluence with unnamed tributary WNW of Big Wall Lake (IA 04-UDM-0220-2). See assessment information for segment IA 04-UDM-0220-1) for previous Section 305(b) assessments for the original 42-mile river reach.]
SUMMARY: The Class B(LR) aquatic life uses are assessed (evaluated) as "partially supported" based on a report of a fish kill in December 2001. Due to the absence of kills subsequent to that kill, this assessment segment will be considered “evaluated” and thus moved from Category 4d (impaired but TMDL not required) to Category 3b (water in need of further investigation) of Iowa's 2006 Integrated Report.
EXPLANATION: A fish kill occurred on this stream reach on December 14, 2001. The kill began just east of Clarion in S5, T91N, R24W, Wright Co., and traveled 11.2 miles to the south line of section 12, T90N, R25W, Wright Co. The kill was caused by the release of 28% nitrogen fertilizer; an estimated 160,000 fish were killed. The party responsible for the kill was identified, and restitution was sought.
According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill during an assessment period indicates "partial support" of the aquatic life uses. If, however, a consent order has been issued to the party responsible for the kill and monetary restitution has been sought for the fish killed, the affected waterbody should be placed in IR Category 4d (impaired but TMDL not required). Thus, this assessment segment was placed into Category 4d of Iowa's 2004 Integrated Report. Also, according to IDNR's assessment/listing methodology, if no additional fish kills have occurred over at least a three-year period (i.e., no kills occurred in the period 2002-2004), the assessment of impairment should be considered “evaluated” (i.e., of lower confidence), and the waterbody segment should be moved from IR Category 4d to IR Category 3b (list of waters in need of further investigation).
