Assessment Comments
Assessment is based on occurrence of fish kills in September 1998 and May 2002.
Basis for Assessment
SUMMARY: The general aquatic life uses are 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, and both kills were caused by animal waste.
EXPLANATION: The previous (2000 and 2002) assessments of the general aquatic life uses of this stream were based on the occurrence of a fish kill in 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 September 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. According to IDNR’s assessment methodology, the occurrence of the May 2002 kill suggests that the aquatic life uses of this river reach are only “partially supported.”
