Assessment Comments
Assessment is based on results of an IDNR investigation of a fish kill in June 2005.
Basis for Assessment
SUMMARY: The general uses of this stream are assessed (monitored) as “partially supported” due to a fish kill in June 2005. 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. Thus, this impairment is appropriate for Category 4d of Iowa’s 2006 Integrated Report.
EXPLANATION: This kill occurred north of Chapin, IA, on or before June 18, 2005 and was attributed to fertilizer. A tank of anhydrous ammonia fertilizer being pulled by a tractor spilled. Despite attempts to control the discharge of the fertilizer, most of the 850 gallons of fertilizer vented to the atmosphere. The hovering of the vapor cloud near the ground, and the dissolving of the ammonia into the water of the unnamed tributary, is believed to be the cause of the kill. An estimated 2,072 non-game fish were killed (minnows, stonerollers, and darters). The estimated value of the fish killed was $201. Approximately 5.25 miles of stream were affected by the kill. The party responsible for the kill was identified.
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 (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.
