Assessment Comments
Assessment remains based on results of an IDNR investigation of a fish kill in August 2005.
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 of this stream remain assessed (monitored) as “partially supported” due to a fish kill in August 2005. The kill was caused by manure discharge from a dairy feeding operation. The party responsible for the kill was identified. This impairment is appropriate for Category 4d of Iowa’s Integrated Report.
EXPLANATION: This kill occurred on or before August 19, 2005, and was caused by manure discharged from a dairy feeding operation. The kill began in Section 36 of T93N, R4W and ended in Section 36 of T93N, R3W. Approximately 1.3 miles of stream were affected; South Cedar Creek, a trout stream, did not appear to have been impacted by the event. A total of 2,226 fish were killed with an estimated value of $660. The party responsible for the kill was identified, and IDNR is seeking restitution for the value of the fish killed and the costs incurred by IDNR in the investigation of the kill.
According to IDNR’s 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. 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 will be placed in IR Category 4d (impaired but TMDL not required). IDNR feels that (1) TMDLs should not be required for kills caused by a one-time illegal or unauthorized release of manure or other toxic substance where enforcement actions were taken and (2) enforcement action is more appropriate, efficient, and effective for addressing a spill-related impairment than is the TMDL process.
