Brush Creek IA 01-VOL-318

The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2012, 2013 and 2014 as part of the DNR/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 2012 CBI score was 61, the 2013 score was 47 and the 2014 score was 40.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 0/3 times in the last five years (2012-2016).This aquatic life assessment is now considered "monitored" based on a change in the 2010 DNR assessment methodology. DNR now requires a segment have two or more biological samples collected from the segment in multiple years between 2012 and 2016 to be considered “monitored”.

This site is approximately 1/10th of a mile from the upper end of the cold water segment. At this time, DNR does not know if the spring is above or below the sampling site and if the sampling data should be judged on a cold or warm water basis. The information below is an additional assessment based on warm water criteria.

The additional assessment of the aquatic life uses based on data collected in 2012, 2013 and 2014 as part of an DNR/SHL sampling project. 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 that were 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 2012 FIBI score was 76 (excellent) and the BMIBI score was 85 (excellent).The 2013 FIBI score was 79 (excellent) and the BMIBI score was 75 (good). The 2014 FIBI score was 86 (excellent) and the BMIBI score was 76 (excellent). If the segment was designated warm water, 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 data collected at stream ecoregion reference sites from 1994-2008. The FIBI BIC for this ecoregion is 62 and the BMIBI BIC is 61.

The Class A1 (primary contact recreation) uses, Class A2 (secondary contact recreation) uses and Class HH (fish consumption) uses remain "not assessed" due to the lack of information upon which to base an assessment.