Assessment Comments
Assessment remains based on results of an IDNR fish kill investigation in November, 2007.
Basis for Assessment
[Note: Prior to the 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 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 remain "not assessed" (IR 3a) due to a lack of water quality information upon which to base an assessment. Beginning with the 2008 listing cycle, the Class B(WW-2) aquatic life uses have ben assessed (monitored) as "partially supported" (IR 5a) based on results of an IDNR fish kill investigation in 2007. New information, however, shows that IDNR sought and received restitution for the value of the fish killed and for the costs of the IDNR investigation of the kill. Thus, this impairment is moved from IR Category 5a to Category 4d (impaired but TMDL not needed) for the current (2014) IR cycle.
EXPLANATION: The fish kill occurred on or before November 2, 2007 and was attributed to Zyglo, a green dye that was discharged by a local industry and passed through the Creston Wastewater Treatment Plant. Approximately 2,583 fish were killed in a 4.5 mile stretch of the river near Creston. The estimated value of the fish was $5,924. Because this discharge occurred through a facility with a discharge permit this assessment was placed in IR Category 5a for the 2008 assessment/listing cycle and has remained in Category 5a.
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. Fish kills attributed to authorized discharges (i.e., a wastewater discharge meeting permit limits) are considered for Section 303(d) listing (IR subcategory 5a) as the existing, required pollution control measures are not adequate to address this impairment, and a TMDL is needed. Thus, this assessment segment was placed in, and remained in, Category 5 of Iowa’s Integrated Report through the 2012 IR cycle.
Also according to DNR's assessment/listing methodology, if a consent order has been issued to the party responsible for the kill and if monetary restitution has been sought for the fish killed, the affected waterbody should be placed in IR Category 4d (impaired but TMDL not required). New information shows that IDNR sought and received restitution for the value of the fish kill and for the cost of the IDNR investigation of the fish kill. Thus, this assessment segment is being placed into Category 4d of Iowa's 2014 Integrated Report. This change in IR category represents a de-listing of the IR Category 5 impairment.
An additional kill occurred on or before September 2, 2008 and was attributed to natural causes (low flow). Approximately 1000 fish were killed. There was no evidence of contamination and the wastewater treatment facility that caused the 2007 fish kill was ruled out.
