Cloie Branch IA 01-TRK-134

The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2011, 2013 and 2014 as part of the IDNR/SHL coldwater stream sampling project.  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 2011 CBI score was 20. The 2013 CBI scores were 15 and 25.   The 2014 CBI scores were 31 and 34. 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 0/5 times in the last 5 years.  

This aquatic life assessment is considered "monitored" based on a change in the 2010 IDNR assessment methodology.  IDNR now requires a segment to have two or more biological samples collected from the segment in multiple years over a five-year period to be considered “monitored”.  This segment had five samples collected from 2011-2014.

In addition, three samples were collected from July to September, 2011 near Durango in Dubuque County (STORET station 12310006); these samples were analyzed for dissolved oxygen, pH, and water temperature.   None of the three samples violated the Class B(CW1) criteria for dissolved oxygen or pH.   Two of the three samples violated the Class B(CW1) criterion for temperature (20C):  the water temperature of the samples collected on July 18, 2011 was 29.3C and the temperature on August 8, 2011 was 23.1C.   According to IDNR guidelines, a minimum of 10 samples collected over a three-year period is needed to develop an assessment of sufficient water quality information available to assess use support.   Thus, based on the water quality sampling data alone, this waterbody would be considered “not assessed”.

Continuous monitoring data collected in 2013 and 2014 for the IDNR/SHL coldwater stream sampling project were examined for DO and stream temperature criteria violations. The lowest DO concentration recorded in 126 days of continuous monitoring was 5.1 mg/L. The daily DO minimum concentration failed to meet the 24-hour DO criterion (5 mg/L) in 0 of 126 days. The percentage exceeding (0%) was less than (passing) the 10% impairment threshold used to assess conventional water quality parameters. The associated statistical analysis confidence level was high (>90%). In contrast, the 16-hour DO criterion (7 mg/L) was exceeded in 22 of 126 days. The percentage exceeding (17.5%) was greater than (failing) the 10% threshold with high statistical confidence (>90%). The maximum stream temperature recorded during the sensor deployment period was 30.9 degrees (C). The B(CW1) temperature criterion of 20 (C) was exceeded in 121 of 126 days. The percentage exceeding (96%) was greater than the 10% impairment threshold with high statistical confidence (>90%). Based on these data, the B(CW1) aquatic life use is assessed as impaired due to DO and temperature. The assessment type is “monitored” because the DO and temperature data meet the requirements for a “monitored” assessment according to the IDNR’s continuous monitoring assessment methodology.

IDNR is unsure that this segment should be classified as B(CW1).  If this segment were assessed as a WW segment, there would be no violations of the temperature and DO water quality standards.  Additionally, the biological assessment of the aquatic life uses would also indicate "full support".  The theoretical monitored biological assessment based on data collected in 2011, 2013 and 2014 as part of the IDNR/SHL sampling project suggests that the aquatic life uses are "fully supporting".  A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biological sampling data.  The biological metrics are based on the numbers and types of fish species collected in the stream sampling reach.  The biological metrics were combined to make a fish community index of biotic integrity (FIBI).  The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).  The 2013 and 2014 FIBI scores were 69 (good) and 76 (excellent).  The 2011, 2013 and 2014 BMIBI scores were 51 (fair), 64, 66, 67, 68 (all good).  The aquatic life use support would be assessed (monitored) as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008. This segment passed the FIBI BIC (2/2 times) and passed the BMIBI BIC (4/5 times) in the last five years.  The FIBI BIC for this ecoregion is 52 and the BMIBI BIC for this ecoregion is 61.  

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