Bear Creek IA 01-VOL-298
south line of S18 T91N R4W (Clayton Co.) to west line of S23 T91N R5W Clayton Co
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 6/22/2016 3:16:36 PM
- Updated
- 11/29/2016 11:02:52 AM
The presumptive Class A1 (primary contact recreation) uses and presumptive Class A2 (secondary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of data for indicator bacteria upon which to base an assessment. The Class B(CW1) coldwater aquatic life uses are assessed (evaluated) as "partially supported" (IR 3b-c) based on based on results of IDNR/SHL biological sampling in 2004 and 2005. Fish consumption uses remain "not assessed" (IR 3a).
The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2004 and 2005 as part of IDNR/SHL coldwater stream sampling projects. A series of biological metrics which reflect coldwater stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa that were collected in the stream sampling reach. The biological metrics were combined to make a coldwater benthic index (CBI). The index ranks the biological integrity of a coldwater stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2004 CBI score was 42 and the 2005 CBI score was 61. The aquatic life use support was assessed (evaluated) as partially supporting (=PS), based on a comparison of the CBI scores with biological impairment criteria (BIC) established for the 2012 Section 305(b) report. The biological impairment criteria were determined from a statistical analysis of data collected at coldwater stream reference sites from 1994-2011. The CW BIC is 60 and this segment passed the CW BIC 1/2 times in a two-year period (2004 & 2005).
IDNR now requires a segment have two or more biological samples collected from the segment in multiple years in a five-year period to be considered “monitored”. This segment had multiple samples collected in a five-year period; however, the data are now more than five years old and are not reliable enough to be considered for a monitored assessment. According to IDNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.