English Creek IA 04-LDM-1057

The Class B(WW2) aquatic life uses are assessed (monitored) as “not supported” based on biological data collected in 2013 and 2014 as part of the DNR/SHL stream sampling project. A series of biological metrics which 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 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 2013 BMIBI scores were 17 and 22 (both poor). The 2014 BMIBI score was 24 (poor). The FIBI scores were unavailable due to fish shocking issues. This stream has extremely high conductivity, TDS and sulfate which renders the fish shocking equipment unable to shock and stun fish for collection. The aquatic life use support was assessed (monitored) as not supporting (=NS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The FIBI BIC for this ecoregion is 33 and the BMIBI BIC for this ecoregion is 41. This segment passed the BMIBI BIC 0/3 times in the last five years. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. This aquatic life assessment is considered "monitored" because there were two or more samples collected from this segment in multiple years over a recent five-year period.

Continuous monitoring data from 2013 and 2014 collected for the DNR/SHL stream sampling project were examined for DO and stream temperature criteria violations. The lowest DO concentration recorded in 53 days of continuous monitoring was 2.3 mg/L. The daily DO minimum concentration failed to meet the 24-hour DO criterion (4 mg/L) in 4 of 53 days and the 16-hour DO criterion (5 mg/L) in 2 of 53 days. The 2013 and 2014 combined percentage exceeding the 24-hour DO criterion (7.5%) was slightly less than (passing) the 10% impairment threshold used to assess conventional water quality parameters; however, the associated statistical analysis confidence level was not high (<90%). The 2013 and 2014 combined percentage exceeding the 16-hour DO criterion (3.8%) was less than (passing) the 10% impairment threshold; however, the associated statistical analysis confidence level was not high (<90%). The maximum stream temperature recorded during the sensor deployment period was 31.2 degrees (C). The temperature criterion for warmwater interior streams (32 C) was exceeded in 0 of 53 days. The percentage exceeding (0%) was less than (passing) the 10% impairment threshold with high statistical confidence (>90%). Based on these data, the B(WW1) aquatic life use is assessed as not impaired by DO and temperature. The DNR’s continuous monitoring assessment methodology specifies that the frequency of violations must exceed the 10% threshold with greater than 90% statistical confidence in order to assess the aquatic life use as impaired. The assessment type is considered as “monitored” because the data meet the minumum requirements of the DNR’s continuous monitoring assessment methodology. Because of the contradictory results showing DO violations in the first year (2013) and not the second year of monitoring (2014), additional continuous monitoring of DO and temperature is strongly recommended.