Assessment Comments
Assessment remains based on IDNR investigations of fish kills that occurred in August 2003, July 2004, and August 2005.
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, 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 (2012) 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" due to the lack of information upon which to base an assessment. The presumptive Class B(WW1) aquatic life uses of this stream remain assessed (evaluted) as “partially supported” due to occurrence of three fish kills during the 2003-2005 period. The kills occurred in August 2003, July 2004, and August 2005. Because the kills occurred more than five years ago, this assessment is now considered “evaluated” (of lower confidence). Nonetheless, the impairment related to the fish kills remains in IR Category 5b of Iowa’s Integrated Report. Two of the kills were caused by release of fertilizer from an ag-chemical dealer; a cause for the third (2005) kill was not identified. The party responsible for the 2003 and 2004 kills was identified, and IDNR received restitution for the value of the fish killed and for the costs of the IDNR investigations. Due to the repeated occurrence of fish kills in East Branch Blue Creek, this waterbody remains assessed as Section 303(d) impaired (IR Category 5b).
EXPLANATION: Three fish kills occurred on this stream during the 2003-2005 period. The first of these kills occurred on or before August 1, 2003; the cause of the kill was attributed to fertilizer. An estimated 3,296 fish were killed with an estimated value of $516. Approximately one-half mile of stream was affected. The kill occurred when an ag-chemical dealer in the city of Walker drained a pit where chemicals are mixed. The water from the pit entered a ditch which is a tributary to East Branch Blue Creek. IDNR indentified the party responsible for this kill and sought and received restitution.
The second of these kills occurred on or before July 10, 2004. Similar to the August 2003 kill, the cause of the kill was attributed to the accidental discharge of 4,000 gallons of water from a fertilizer tank from the same ag-chemical dealer in Walker, IA, that caused the kill in August 2003. An estimated 7,744 fish were killed with an estimated value of $1,341. Approximately 1.5 miles of stream was were affected by the kill; the kill began in Section 4 of T86N, R8W and ended in Section 9 of T86N, R8W. Restitution was also sought and received for this fish kill.
The third of these kills occurred on or before August 14, 2005. Despite a thorough investigation by IDNR field staff of the potential causes and sources of the kill—especially due to the previous kills in August 2003 and July 2004—no definitive cause or source of the kill was identified. A new tile line had recently been installed. Based on conversation with the installer of the line, a hypothesis was developed that recent rains had flushed contaminated water from a low spot in the new tile line into the stream, thus causing the kill. An estimated 15 fish were killed; no estimate of valuation was calculated. The kill occurred on the south side of Walker; approximately 0.25 miles of stream were affected.
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. However, due to the repeated occurrence of fish kills, this segment is assessed (evaluated) as impaired and was placed in Category 5 of Iowa’s 2008 Integrated Report (=Section 303(d) list) where it remains for the 2012 Integrated Report.
