Assessment Comments
Assessment remains based on results of an IDNR investigation of a fish kill in August 2001.
Basis for Assessment
[Note: Prior to the current (2008) Section 305(b) cycle, this stream segment was classified only for general 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 and for Class B(WW1) aquatic life uses. According to the Iowa Water Quality Standards, all perennial rivers and streams and all intermittent streams with perennial pools that are not specifically listed in the Iowa surface water classification are designated as Class A1 and Class B(WW1) waters. Thus, for the current (2008) assessment, perennial flow is presumed, and the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW1) 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 presumpitve Class B(WW1) aquatic life uses remain assessed (evaluated) as "partially supported" based on a report of a fish kill in August 2001. Due to the absence of kills subsequent to that kill, this assessment segment was considered “evaluated” and was moved from Category 4d (impaired but TMDL not required) of Iowa's 2004 Integrated Report to Category 3b (water in need of further investigation) of Iowa's 2006 IR. This stream segment remains in IR Category 3b of Iowa's 2008 IR.
EXPLANATION: A fish kill occurred on this stream segment on August 18, 2001. The kill affected 1 mile of this unnamed tributary to Otter Creek in sections 33 and 28 to T90N, R9W, Buchanan County approximately 3 miles south of Hazleton. The kill was caused by movement of land-applied hog manure and waste milk to this unnamed creek. This kill was not related to rainfall runoff. The responsible party 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 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).
