Crane Creek IA 01-TRK-213
from confluence with unnamed tributary (NW 1/4 S33 T99N R13W Howard Co.) to confluence with unnamed tributary in S7 T99N R13W Howard Co. approximately 2 miles north of Saratoga.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 9/15/2016 8:25:01 AM
- Updated
- 11/21/2016 2:49:28 PM
The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed (evaluated) as "partially supported" (IR 5b-t) based on results of IDNR/SHL biological sampling in 2006 and 2010.
The assessment of the aquatic life uses was based on data collected in 2006 and 2010 as part of the IDNR/SHL stream REMAP and follow-up sampling projects. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2006 FIBI score was 68 (good) and the BMIBI score was 40 (fair). The 2010 FIBI score was 70 (good) and the BMIBI score was 48 (fair). The aquatic life use support was assessed as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The non-riffle habitat FIBI BIC for this ecoregion is 44 and the artificial substrate BMIBI BIC for this ecoregion is 52. This segment passed the FIBI BIC 2/2 times and the BMIBI BIC 0/2 times in the last nine years.
This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology. IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a recent five-year period (2010-2014) to be considered “monitored”. This segment had multiple samples collected in the previous nine years (2006-2014); however, the samples were not collected during a recent five-year period. Additionally, the 2006 sample was collected outside of the IDNR index period (7/15-10/15) and should not 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). However, despite this change in assessment methodology and type, this waterbody remains in IR Category 5b-t and remains on Iowa’s 2012 Section 303(d) list of impaired waters.