Steeles Branch IA 01-TRK-178

The Class A1 and A2 uses are assessed (monitored) as “not supported” due to levels of indicator bacteria (E. coli) that exceed the respective Class A1 and Class A2 geometric mean criteria.  The geometric means of indicator bacteria (E. coli) in the 16 samples collected during the recreational seasons of 2012, 2013, and 2014 at Steeles Branch Site 1 were 1,232, 575, and 318 orgs/100 ml, respectively.  The geometric means of indicator bacteria (E. coli) in the nine samples collected during the recreational seasons of 2012, 2013, and 2014 at Steeles Branch Site 3 were 2,866, 524, and 20 orgs/100 ml, respectively.  Five of the six recreation season geometric means exceed Iowa’s Class A1 geometric mean criterion of 126 E. coli orgs/100 ml, and two of six also exceed the Class A2 geometric mean criterion of 630 E. coli orgs/100 ml, thus indicating nonsupport of both the Class A1 and A2 water contact recreation uses.  Thirteen of the 16 samples (81%) at Steeles Branch Site 1 exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml, and five of nine samples (56%) exceeded this criterion at Steeles Branch Site 3.  Compared to the Class A2 single sample maximum criterion of 2,880 orgs/100 ml, two of the 17 samples at Site 1 (12%) and one of the 10 samples at Site 3 (10%) exceeded this criterion.  According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean is greater than the respective criterion (126 orgs/100 ml for Class A1 and 630 orgs/100 ml for Class A2), the contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). 

The assessment of support of the Class B(CW1) coldwater aquatic life uses is changed from “partially supported” (IR 3b) due to a fish kill to “not assessed” (IR 3a).  The fish kill occurred in a tributary of Steeles Branch on August 2, 2002, and resulted from the spillage from a 500 gallon tank containing liquid animal feed containing molasses; the tank slid off a flatbed truck into a road ditch; an undetermined amount of liquid feed was spilled.  Approximately 0.5 miles of this tributary was affected; a total of 153 fish was killed.  The party responsible for this kill was identified.  Iowa DNR sought and received restitution for the value of the fish killed and the cost of investigation.  Steeles Branch was not affected by this kill. 

Listing history for this fish kill impairment:  According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill during an assessment period indicates "partial support" of the aquatic life uses.  If, however, a consent order was issued to the party responsible for the kill and monetary restitution was sought for the value of the fish killed and the costs incurred by IDNR during the fish kill investigation, the affected waterbody should be placed in IR Category 4d (impaired but TMDL not required).  Thus, this waterbody was included in Category 4d for the 2004 through 2008 IR cycles.   Because no additional fish kills had occurred in this stream segment over at least a five-year period, the impairment was moved from IR Category 4d to IR Category 3b (list of waters in need of further investigation) for the 2010 IR cycle.  Because no additional kills have been reported for this non-303(d)-impaired stream for over 10 years, any fish kill-related impacts in this segment have likely dissipated, and thus the aquatic life uses are considered “not assessed”; thus, this segment is moved to IR Category 3a (not assessed) for the current (2016) cycle.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream reach.