East Fork Medicine Creek IA 05-GRA-1350

The presumptive Class A1 (primary contact recreation) uses are assessed (evaluated) as "partially supported" (IR 3b) due to identification of an impairment for indicator bacteria (E. coli) in the adjacent downstream segment by the Missouri Department of Natural Resources.

The (evaluated) assessment of the Class B(WW2) aquatic life uses was based on data collected in 2005 as part of the IDNR/SHL REMAP 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 2005 FIBI score was 0 (poor) and the BMIBI score was 13 (poor).   The aquatic life use support was assessed 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.   The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008.   This segment passed the FIBI and BMIBI BICs 0/1 times in 2005.

This aquatic life assessment is considered "evaluated" because there were not two or more samples collected from this segment in multiple years over a recent five-year period.   Additionally, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).   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 was previously on Iowa’s Section 303(d) list and thus remains on Iowa’s Section 303(d) list of impaired waters (IR Category 5b-t).