Assessment Comments
Assessment is based on results of an IDNR investigation of a fish kill in April 2004.
Basis for Assessment
[Note: Prior to the current (2008) Section 305(b) cycle, this stream segment was designated only for Class B(LR) aquatic life 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. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current (2008) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses are "not assessed" due to a lack of water quality information upon which to base an assessment. The Class B(WW-2) aquatic life uses of this stream are assessed (monitored) as “partially supported” due to a fish kill in April 2004. The kill was caused by animal waste from a hog confinement operation. The party responsible for the kill was not identified. This impairment is appropriate for Category 5b of Iowa’s 2006 Integrated Report (=Section 303(d) list).
EXPLANATION: This kill occurred on April 27, 2004. The cause of the kill was identified as animal waste from hog confinement operation. Only 1 fish was reported killed*; no value estimate was provided. No location information for the kill was provided. According to the IDNR investigation, the spill of animal (swine) waste sent approximately 1,500 gallons of manure into David’s Creek. The umbilical line (hose that runs from the confinement building to the tractor applying the manure) ruptured, thus spilling manure onto the land and through a tile line before entering the creek. Dams were constructed to stop the flow of manure into the stream. The party responsible for the kill was not 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 (2005-2007) 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 a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b. Although documentation of this fish kill suggests that the party responsible for the kill was identified, IDNR records do not indicate that IDNR sought restitution for the value of the fish killed or for the costs incurred by DNR during the investigation of the kill. The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources. For previous assessment/listing cycles, IDNR had considered fish kill-impaired (IR 5b) waters with no subsequent kills in the three year subsequent to the kill as appropriate for de-listing and for movement to IR categories 2b or 3b (i.e., Iowa’s list of waters in need of further investigation). Due, however, to EPA uncertainty regarding the full recovery of the aquatic life following the kill, any existing fish kill (5b) impairment will remain in IR Category 5b until more recent monitoring has shown full recovery of the aquatic communities affected by the kill. Thus, this assessment segment will remain in Category 5b of Iowa’s 2008 Integrated Report.
*Note: IDNR staff (JRO & TFW) surveyed Davids Creek in October 2001 as part of an IDNR stream use assessment. The fish community in the lower portion of this stream was found to be very productive and very diverse (15 species with eight species reported as "common"). Although field notes from that survey suggest that aquatic habitat in the upper reaches of this stream is limited, the report that only one fish was killed during the April 2004 kill should not be taken to imply that this stream is incapable of supporting an aquatic commuity.
