Assessment Comments
Assessment remains based on (1) results of two fish kill investigations in 2008, (2) results of a fish kill investigation in June 2011, and (3) results of an IDNR fish kill follow-up survey in October 2013.
Basis for Assessment
[Note: Prior to the 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, 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 (2014) 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 remain "not assessed" due to the lack of information upon which to base an assessment. The assessment of support of the Class B(WW-2) (aquatic life) uses is changed from "partially supported" (IR 5b) based on occurrence of pollutant-caused fish kills in 2008 and 2011 to "not assessed" (IR 3a) based on results of fish kill follow-up monitoring in 2013. This change in assessment respresents a de-listing of the previous impairment of the Class B(WW2) aquatic life uses.
EXPLANATION: The first of these fish kills occurred before August 17, 2008. The kill likely occurred up to 4 days prior to August 17, 2008. Approximately 2,720 fish were killed along a half mile of Whitewater Creek. The value of the fish was reported as $498.44. No definite cause was identified although aerial spraying was listed as a possible cause.
The second kill occurred before September 22, 2008 due to the poor condition of fish carcasses at the time of the investigation. The kill affected approximately 3084 fish, although it was noted that small-bodied fish were likely severely under-represented. The fish were valued at $4,311.70. The following species were identified: common shiner, johnny darter, smallmouth bass, stonecat, and white sucker. A high-quality smallmouth bass fishery exists in Whitewater Creek and dead fish encountered in the census provide evidence that this kill impacted an important resource for recreation.
The third kill occurred on or before June 19, 2011; this kill was caused by animal waste. Approximately 104,000 fish were killed over nearly 18 miles of stream. The value of the fish was reported as $96,482.22; the cost of the DNR investigation was estimated as $1,190.07. The cause of the kill was identified as animal waste from hog and cattle feedlots. According to the IDNR fish kill report (https://programs.iowadnr.gov/fishkill/detail.aspx?fkid=830), the kill was caused by ammonia toxicity associated with manure discharge as determined by IDNR Field Office #1 field tests. An open hog lot and a cattle operation were on site. The kill originated in the SW 1/4 of Section 18, T88N, R1E in Whitewater Creek (1 mile SE of Epworth) and proceeded downstream to the NE 1/4 of Section 26, T87N, R1W (Highway 151 Bridge) for a total distance of 17.95 miles. Observations of fish and invertebrates at the stream suggest a complete kill in the upper 2.5 miles of the assessment area (Lone Pine Rd to Pilot Grove Road) and an extensive kill from Pilot Grove Rd to East Pleasant Grove Rd (3.2 additional miles). From East Pleasant Grove Rd to the confluence with Curran Branch (5 miles) a moderate to partial kill appeared to have occurred. In the downstream 7 plus miles of assessed stream a partial kill appears to have occurred with additional dead fish floating in from upstream areas."
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. 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 records show that the party responsible for the 2011 kill was identified, and IDNR sought and has received restitution for the value of the fish killed and the costs incurred by IDNR during investigation of the kill. Thus, this assessment segment was appropriate for Category 4d of Iowa’s Integrated Report.
This stream segment’s fish community was sampled on October 8, 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 550 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 5,500 fish per mile compared to the Level IV ecoregion 47f average of approximately 1,500 fish per mile; 89% of the expected fish taxa for this ecoregion were sampled. For detailed results of this sampling, see https://programs.iowadnr.gov/bionet/Sites/961. 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 June 2011 fish kill event. Thus, the assessment of aquatic life use support for this stream segment is being moved from impairment Category 4d of Iowa’s Integrated Report to Category 3a (designated use not assessed).
