Assessment Comments
Assessment is based on occurrence of a fish kill in May 2002.
Basis for Assessment
SUMMARY: The general uses remain assessed (monitored) as "partially supported" due to occurrence of fish kills in September 1998 and May 2002; both kills affected Brown Creek and its confluent, the Des Moines River; both kills were caused by animal waste.
EXPLANATION: The 2000 and 2002 assessments of the general uses of this stream were based on the occurrence of a fish kill in September 1998 (see assessment for the 2000 and 2002 reports). According to IDNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill within the most recent three-year period indicates ongoing impairment of the aquatic life uses. Although three years had elapsed since the 1998 kill, an additional kill, also caused by an accidental release of animal waste (liquid manure), occurred on May 24, 2002. According to the fish kill report, an underground pipe broke resulting in the drainage of a holding lagoon. The liquid manure entered Brown Creek and traveled downstream to the Des Moines River; an estimated 33,400 fish were killed over an 18-mile stream/river reach. The party responsible for both the 1998 and 2002 kills was identified, and IDNR sought restitution for the value of the fish killed.
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. Because the most recent kill on this stream occurred during the current (2006) assessment period (I.e., 2002-2004), this assessment will remain in Category 4d of Iowa's 2006 Integrated Report.
