Assessment Comments
Assessment remains based on results of a fish kill investigation in August 2009 and is based on results of IDNR fish kill follow-up monitoring in July 2013.
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 information upon which to base an assessment. The presumptive Class B(WW1) aquatic life uses were assessed (monitored) as "partially supported” (IR 4d) based on the results of a fish kill investigation in August 2009. However, results of IDNR fish kill follow-up monitoring in July 2013 show recovery of the fish community in this assessment segment, and thus the IR 4d impairment is moved to IR Category 3a ("not assessed") for the 2014 IR cycle.
EXPLANATION: The kill occurred on or before August 12, 2009. Approximately 89 fish were killed along a 3.05 mile stretch of the creek four miles north of Kalona. The suspected cause of the kill was runoff from a dairy operation. The estimated value of the fish was $30.19. Updated information on this fish kill indicates that IDNR sought and received restitution for this fish kill.
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. Thus, this assessment segment was placed in Category 4d of Iowa’s 2012 Integrated Report.
This stream segment’s fish community was sampled on July 25, 2013 as part of the IDNR Watershed Improvement and Water Monitoring sections’ fishkill follow up monitoring program. Sampling methods described in IDNR’s fish kill follow-up protocol (Attachment 5 of Iowa’s 2014 assessment/listing methodology) were followed. Approximately 525 feet of stream were sampled using a single pass with one backpack electro fishing units. Results of this sampling show that this stream supports approximately 6,000 fish per mile compared to the Level IV ecoregion 47f average of approximately 1,600 fish per mile; 89% of the expected fish taxa for this ecoregion were sampled. The results from this follow-up sampling and comparison of these results to ecoregion averages suggest that the fish community of this stream segment is similar to or better than non-fishkill impacted streams. Although the results of the fishkill follow-up sampling lack the scientific rigor to determine whether the designated aquatic life uses are “fully supported,” the results do indicate that the stream has recovered from the August 2009 fish kill event. Thus, this stream segment is being moved from impairment Category 4d of Iowa’s Integrated Report to IR Category 3a (designated use not assessed).
