Assessment Comments
Assessment is based on results of an IDNR investigation of a fish kill in November 2004.
Basis for Assessment
SUMMARY: The general uses of this stream are assessed (monitored) as “partially supported” due to a fish kill in November 2004. The kill was caused by a spill of ammonia fertilizer. The party responsible for the kill was identified, and IDNR has sought restitution for the value of the fish killed and the costs incurred by IDNR during investigation of the kill. This impairment is appropriate for Category 4d of Iowa’s 2006 Integrated Report.
EXPLANATION: This kill occurred on or before November 10, 2004 in Section 20 of T80N, R41W of Harrison County. The cause of the kill was attributed to fertilizer. A truck pulling an anhydrous ammonia tank rolled over and spilled its contents near South Picayune Creek. An undetermined amount of anhydrous ammonia traveled into the creek. The kill traveled approximately 700 feet from where Picayune Creek empties from a road culvert through County Road F 32 east of Woodbine and stopped at an emergency dam constructed downstream of road culvert. Following the spill, ammonia levels in the contained area of the creek were between 75 and 150 parts per million (ppm), while levels downstream were between zero and 2.5 ppm. Ammonia levels of about 8 to 10 ppm can cause a fish kill, depending on stream temperature and pH. An estimated 93 fish were killed with an estimated value of $768. The responsible party 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 (2002-2005) 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.
