Assessment Comments
Assessment remains based on results of an IDNR investigation of a fish kill in April 2000.
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 the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed (evaluated) as "partially supported" based on a report of a fish kill in April 2000. Due to the absence of kills in the three years subsequent to that kill, this assessment segment was considered “evaluated” and thus was moved from Category 4d (impaired but TMDL not required) to Category 3b (water in need of further investigation) of Iowa's 2006 Integrated Report. This assessment remains in Category 3b of Iowa's 2008 Integrated Report.
EXPLANATION: A fish kill occurred on this stream segment on April 6, 2000. The kill affected 6.5 miles of Deer Creek beginning at the Iowa/Minnesota state line and extending downstream at the west line, S35, T100N, R19W, Worth County; an estimated 59,000 fish were killed. The kill was caused by a fertilzer spill at an ag-chemical dealer in Myrtle, MN.
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 following the kill, 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).
