Assessment Comments
Asssessment 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 13, 2004 in Section 2 of T89N, R43W, Plymouth County. The cause of the kill was attributed to fertilizer. An ammonia nurse tank reportedly came unhooked when a truck crossed a bridge on 340th St. in Plymouth County around 10 PM Saturday, November 13, releasing approximately 25 pounds of ammonia into the creek. The IDNR investigation showed that ammonia levels in the creek were near 50 parts per million (ppm). Ammonia levels of about 8 to 10 ppm can cause a fish kill, depending on stream temperature and pH. The kill affected approximately 3 miles of this tributary. An estimated 7,323 fish were killed with an estimated value of $782. The responsible party was identified.
According to the IDNR assessment and 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.
