Sugar Creek IA 02-CED-492

This fish kill occurred east of Tipton in Cedar County on or before August 5, 2015.  The kill was attributed to a spill of animal waste from a hog confinement.  An estimated 22,807 fish were killed over 3.8 miles of stream.  The value of the fish killed was estimated at $9,259.97, and the cost of the Iowa DNR investigation of the kill was $303.33.  Based on this information, presumptive Class B(WW1) aquatic life uses are assessed as “partially supporting”.  The following are notes from the Iowa DNR fish kill investigation:

Responsible party said a coupler broke while he was draining a hog confinement and the spilled manure made it to a drainage ditch that entered the stream.  The kill started below a drainage ditch in Sugar Creek in section 29 [T81N, R2W] (UTM X = 658099, Y = 4628601) and extended approximately 3.8 miles to just downstream of Red Star Road  in section 9 of Center Township in Cedar County (UTM = 658898, Y = 4624765).

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).  The responsible party for this kill was identified, and Iowa DNR sought and received partial restitution for the value of the fish killed and the cost of the Iowa DNR investigation.  Thus, this assessment segment is placed in Category 4d of Iowa’s 2016 Integrated Report.

The presumptive Class B(WW1) aquatic life uses also remain assessed (evaluated) as "partially supported" based on results of biological monitoring conducted in 1996 and 2001.  The biological assessment was based on data collected in 1996 and 2001 as part of the IDNR/SHL stream biocriteria project.  The 1996 FIBI score was 38 (fair) and the BMIBI score was 41 (fair).  The 2001 FIBI score was 50 (fair) and the BMIBI score was 58 (good).  This segment passed the FIBI BIC 2/2 times and passed the BMIBI BIC 1/2 times in the last 19 years.  The aquatic life use support was assessed (evaluated) as partially supported (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008.  The FIBI BIC for this ecoregion is 36 and the BMIBI BIC for this ecoregion is 51.  Even though this site passed the FIBI BIC (2/2) and failed the BMIBI BIC (1/2), it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it is a small presumed BWW1 (formally general use) stream and doesn’t fall in the calibrated watershed size.  Additionally, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).  

Prior to the changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008, this stream was classified only for general uses due to the inability of the stream to support a viable aquatic community at low-flow conditions.  IDNR’s existing biological assessment protocol, however, was calibrated to aquatic life reference conditions in larger wadeable streams with perennial flow.  The aquatic environment of most headwater streams is one of extremes in water quality.  Consequently, intermittent headwater streams tend to have biological diversity that is low relative to more stable aquatic environments of larger streams with perennial flow.  Thus, the use of biological assessment methods developed for the ecologically more stable and diverse streams will likely overstate the existence of impairment in headwater streams.  

Results of chemical/physical water quality monitoring conducted in 2001 in support of TMDL development show no violations of Class B(WW1) state water quality criteria for conventional parameters and ammonia-nitrogen in the nine monthly samples collected between March and November 2001 at the site 2 miles E of Tipton (Site 9) (the maximum value of ammonia-nitrogen was 0.12 mg/l).  These results suggest "full support" of the aquatic life uses.