South Bear Creek IA 01-UIA-252

The presumptive Class A1 (primary contact recreation) uses are assessed as “partially supporting”.  The geometric means of indicator bacteria (E. coli) in the 21 samples collected during the recreational seasons of 2012 through 2014 at UIRW Site 23 were as follows:  the 2012 geometric mean was 50 orgs/100 ml, the 2013 geometric mean was 135 orgs/100 ml, and the 2014 geometric mean was 125 orgs/100 ml.  Only the 2013 geometric mean exceeded the Class A1 criterion of 126 orgs/100 ml and then only very slightly (by 9 orgs/100 ml).  Six of the 21 samples (29%) exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml.  According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if a recreation season geometric means exceeds the respective water quality criterion, the contact recreation uses should be assessed as “impaired” (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  All three geometric means met and were far below the Class A2 geometric mean criterion of 630 orgs/100 ml.  According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if all recreation season geometric means meet the respective water quality criterion, the contact recreation uses are "fully supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  Despite the new impairment of the Class A1 uses, this stream segment continues to show some of the lowest stream bacteria levels in the state of Iowa.

Based on the 2012-2014 water quality results and 2016 updated IDNR Fisheries trout reproduction data, the Class B(CW1) coldwater aquatic life uses are assessed (monitored) as “fully supporting”.  Results of water quality monitoring from 2012 to 2014 at Upper Iowa River Watershed Site 23 do not indicate impairment of the Class B(CW1) uses.  Analysis of 14 samples for ammonia, temperature, and pH showed that none of the samples collected violated the respective Class B(CW1) criteria.

The updated summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau in January 2016 also suggests the Class B(CW1) uses are "fully supported".  According to the updated summary, Bear Creek (aka South Bear Creek) is in the group of Iowa coldwater streams that supports natural reproduction of trout.  Based on results of surveys by the IDNR Fisheries Bureau, this stream is placed in the category of Iowa trout streams that exhibit recent, but inconsistent reproductive success and that are generally not capable of maintaining a viable population of Brown Trout at this time (a Category II stream).

The Class B(CW1) coldwater aquatic life uses were historically assessed (evaluated) as "partially supported.”  These uses were assessed as "partially supported" for the 2000 through 2004 assessment cycles due to occurrence of a fish kill on August 5, 1999 northwest of Highlandville in Winneshiek County.  As stated in the assessment developed for the 2000 report, the kill followed a 2-3 inch rainfall event; no other water quality problems were observed.  An estimated 3,200 fish were killed.  No responsible party for the kill was identified.  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 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.  For its draft 2006 assessment, IDNR considered this stream segment to be “not assessed” (IR Category 3a) and proposed this impairment for removal from Iowa’s 2006 Section 303(d) list.  According to IDNR’s assessment/listing methodology at that time, if the most recent pollution-caused fish kill occurred on this stream segment more than six years ago (i.e., before the 2000-2005 period), any toxic impacts associated with the kill are assumed to have dissipated, and the affected water would be considered “not assessed.”  

IDNR believes that the combination of the water quality and trout reproduction data indicate that there has been a full recovery of the aquatic life in this stream following the fish kill.  IDNR has de-listed the 5b impairment due to the 1999 fishkill and the aquatic life uses of this segment now reside in IR 2a. 

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