East Branch Boone River IA 04-UDM-6367

The fishkill occurred on or before September 15, 2009, and affected the East Branch of the Boone River near Kanawha. The kill affected approximate 945 fish and was attributed to pesticides, possibly due to aerial spraying. The value of the fish was estimated to be $4,178.42. At the time of this assessment (2016) there is no record that DNR sought or 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. 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. 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.

This stream segment’s fish community was sampled on October 8, 2014, 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 assessment/listing methodology) were followed.  Approximately 440 feet of stream were sampled using a single pass with two backpack electro fishing units.  Results of this sampling show that this stream supports approximately 4,800 fish per mile compared to the Level IV ecoregion 47b average of approximately 3,000 fish per mile; 73% of the expected fish taxa for this ecoregion were sampled.  For detailed results of this sampling, see https://programs.iowadnr.gov/bionet/Sites/975.  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 September 2009 fish kill event.  Thus, the assessment of aquatic life use support for this stream segment is being moved from impairment Category 5b of Iowa’s Integrated Report to Category 3a (designated use not assessed).