Bear Creek IA 01-YEL-440
Alternate name(s) for this segment: Unnamed Creek (aka Bear Cr.)
mouth (S13 T96N R5W Allamakee Co.) to north line of S12 T96N R5W Allamakee Co.
The presumptive Class A1 and Class A2 uses remain assessed as “partially supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BCW1 use remains assessed as "not supported" due to the historical impairment based on dissolved oxygen levels. All other designated uses were “not assessed”. Note: A TMDL for the bacterial impairment for streams in the Yellow River basin was prepared by Iowa DNR in 2012 and was approved by U.S. EPA in February 2013. Due to completion of the TMDL, the Integrated Report categories for the Class A1 and Class A2 recreational uses were changed from 5p (impaired; TMDL needed) to 4a (impaired; TMDL approved). Because not all impairments identified for this assessment segment are covered by the TMDL (aquatic life impairment due to low dissolved oxygen), this segment remains in Category 5a of Iowa's Integrated Report (impaired and TMDL required).
Sources
of Data: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2008-2009 15030006 Bear Creek nr Co. Rd. X26 Presumptive
Class A1 - Indicator Bacteria: Historical Site ID Data Source ID # Samples / # Years 2008 Geometric Mean 2009 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 15030006 6 26 / 2 218 874 Yes 15 58% Yes Evaluated Partial Presumptive
Class A2 - Indicator Bacteria: Historical Site ID Data Source ID # Samples / # Years 2008 Geometric Mean 2009 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 15030006 6 26 / 2 218 874 Yes 10 38% Yes Evaluated Partial Class
BCW1 - Conventional Parameters: Historical Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations % Acute/ Chronic Violations Significantly >10% Violations Assessment Type Support Level 15030006 6 Ammonia 25 / 2 0.39 0.07 0.05 0 / 0 0% / 0% No Evaluated Full 15030006 6 Dissolved oxygen 12 / 2 11.9 10.34 10.65 NA / 0 NA / 0% No Evaluated Full 15030006 6 pH 12 / 2 8.1 7.9 8.0 0 / NA 0% / NA No Evaluated Full 15030006 6 Temperature 12/ 2 15.3 14.1 14.7 0 / 0 0% / 0% No Evaluated Full These
results are in contrast to the 2004-06 period when 42 of 80 samples violated
the Class BCW1 criterion for dissolved oxygen of 7.0 mg/l. Based on DNR's
assessment methodology, however, two consecutive assessment/listing cycles
without significantly greater than 10% of the samples violating the standard
are necessary to suggest de-listing of an impairment due to low dissolved
oxygen. Therefore, the impairment for dissolved oxygen remained in place for
the current assessment/listing cycle and continues. Class
BCW1 – Trout Natural Reproduction: In
contrast to the WQ data, based on the January 2020 trout reproduction in Iowa
streams summary prepared by the DNR Fisheries Bureau, the Class BCW1 coldwater
aquatic life use of Bear Creek was assessed as "fully supported".
According to the updated summary, this stream was placed in Category II:
streams that exhibit recent but inconsistent reproductive success and
occasional stocking may be needed to maintain the trout population. Class
HH - No Data