Long Dick Creek IA 03-SSK-960

The Class B(WW2) aquatic life uses remain assessed (evaluated) as “partially supported” based on biological data collected in 2003 and 2008 as part of the DNR/SHL stream biocriteria 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 2003 FIBI scores were 33, 34 (both fair) and the BMIBI scores were 33, 44 (both fair). The 2008 FIBI score was 44 (fair) and the BMIBI score was 40 (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 FIBI BIC for this ecoregion is 32 (non-riffle) and 53 (riffle) and the BMIBI BIC for this ecoregion is 62. The 34 and 44 FIBI scores correspond with a non-riffle site and passed the non-riffle BIC (32), while the 33 FIBI score was from a riffle site, thus it failed to meet the riffle BIC (53). In addition, all sites failed to meet the BMIBI BIC of 62. This segment passed the FIBI BICs 2/3 times and passed the BMIBI BIC 0/3 times in the past 14 years.

This aquatic life assessment is now considered "evaluated" 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 over a recent five-year period to be considered “monitored”. This segment had multiple samples collected in the previous 14 years (2003-2016); however, the multiple samples were not collected during 2012-2016. According to DNR’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). DNR 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 Section 303(d) list of impaired waters.