Buck Creek IA 01-YEL-428

Assessment Comments

Assessment based on 2007 IDNR/UHL biological monitoring data: 3/4 coldwater biological indicators met the criteria - fully supporting (FS).

Basis for Assessment

[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(CW) aquatic life uses.   Due to changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), this segment is also now presumptively designated for Class A1 (primary contact recreation) and Class A2 (secondary contact recreation) uses.   This segment remains designated for coldwater aquatic life use (now termed Class B(CW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption) uses.   This segment remains an HQ water.]

SUMMARY:  The Class A1 (primary contact recreation) uses and the Class A2 (secondary contact recreation) uses are "not assessed" due to the lack of information upon which to base an assessment.   The Class B(CW1) coldwater aquatic life uses are assessed (monitored) as "fully supported" based on results of 2007 IDNR/UHL benthic macroinvertebrate sampling.   Fish consumption uses are not assessed due to the lack of fish contaminant monitoring in this assessment segment.

EXPLANATION:  The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2007 as part of the IDNR/UHL coldwater stream sampling project.   A series of four (4) coldwater biological indicators, which reflect stream water quality and habitat integrity, were calculated from the biocriteria sampling data.   The coldwater biological indicators are based on the numbers and types of coldwater benthic macroinvertebrate taxa that were collected the stream sampling reach.   Sites where only a benthic macroinvertebrate sample was obtained or sites that do not receive any type of trout stocking are scored on the benthic macroinvertebrate data only.   Non-trout stocking sites that score 3 or 4 are fully supporting (FS), sites that score 1 or 2 are partially supporting (PS), and sites that score 0 are not supporting (NS).   The 2007 coldwater biological indicator score was 3/4.   The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the coldwater biological indicator score with biological assessment criteria established for this Section 305(b) report.   The coldwater biological indicators were determined from a statistical analysis of data collected at coldwater stream ecoregion reference sites from 1994-2008 and with assistance from the IDNR Fisheries Bureau.

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology.   IDNR now requires a segment have two or more biological samples collected from the segment in multiple years between 2004 and 2008 to be considered “monitored”.   This segment had a single sample collected in 2007.   Despite this change in assessment methodology and type, this waterbody was placed in IR Category 2a.