Assessment Comments
Assessment is based on results of two fish kill investigations in 2008.
Basis for Assessment
SUMMARY: The Class B(WW-2) (aquatic life) uses are assessed (monitored) as "partially supported" due to the occurrence of two fish kills in 2009.
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 2720 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 $4311.70. 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.
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 (2007-2009) 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. Thus, this assessment segment will be placed in Category 5b of Iowa’s 2010 Integrated Report
