Assessment Comments
Assessment remains based on results of an IDNR investigation of a fish kill in August 2004.
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 presumptive Class B(WW1) aquatic life uses of this stream remain assessed (monitored) as “partially supported” due to a fish kill in August 2004. The kill was caused by animal waste from an open feedlot. Although the party responsible for the kill was identified, IDNR records do not indicate that IDNR sought restitution for the value of the fish killed or costs incurred by DNR during the investigation of the kill. Thus, this impairment is appropriate for Category 5b of Iowa’s Integrated Report (=Section 303(d) list).
EXPLANATION: Regarding support of aquatic life uses, the fish kill occurred on or before August 3, 2004 and occurred two miles north of Luxemburg on Highway 52 in Section 9 of T90N, R2W, Dubuque County; approximately 0.8 miles of stream was affected by the kill. The kill was attributed to animal wastes from an open (swine) feedlot. An estimated 6,574 fish were killed with an estimated value of $628. Fish killed were non-game species, primarily minnows (including creek chubs, stonerollers, blacknose dace, and southern redbelly dace). The party responsible for the kill was identified.
According to the IDNR assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill is identified, and the cause is either known, or suspected, to be a “pollutant”, the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing. Fish kills attributed to a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b. The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources.
