Maple River IA 06-LSR-1585

Assessment Comments

Assessment historically based on 1997 IDNR/SHL biological sampling data: FIBI = 35 (fair); BMIBI = 71, 68 (good). FIBI BIC = 31, BMIBI BIC = 54. Due to the age of the data (>10 years), the assessment of the Class B(WW-1) aquatic life uses is changed from "fully supported" to “not assessed”.

Basis for Assessment

Assessment historically based on 1997 IDNR/SHL biological sampling data (see below).   Due to the age of the data (>10 years), the assessment of the Class B(WW-1) aquatic life uses is changed from "fully supported" to “not assessed”.

[Note  Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(WW) aquatic life uses, including fish consumption uses.   Due to changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008 (see http://www.iowadnr.gov/Portals/idnr/uploads/water/standards/files/swcdoc2.pdf), this segment is also now presumptively designated for Class A1 (primary contact recreation) uses.   This segment remains designated for warmwater aquatic life use (now termed Class B(WW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).]

SUMMARY:  The Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment.   Due to the age of the data, the assessment of the Class B(WW-1) aquatic life uses is changed from "fully supported" (evaluated) based on results of IDNR/SHL biological (biocriteria) sampling in 1997 to “not assessed”.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.  

EXPLANATION:  For previous assessment/listing cycles, the assessment of the Class B(WW1) aquatic life uses was based on data collected in 1997 as part of the IDNR/SHL stream biocriteria project.   The 1997 FIBI score was 35 (fair) and the BMIBI scores were 71 (good) and 68 (good).   The aquatic life use support was assessed (evaluated) as fully supporting (=FS), 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 31 and the BMIBI BIC for this ecoregion is 54.   This segment passed the FIBI BIC 1/1 times and passed the BMIBI BIC 2/2 times in the last 14 years.   Because the data upon which these assessment were based are now more than ten years old, the Class B(WW1) uses are now considered “not assessed.”  As water quality data age, they are less able to represent current water quality conditions.   As data age beyond ten years, their ability to represent current water quality conditions is increasing suspect.   Additional monitoring is needed in this assessment segment to update status of its aquatic communities.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river segment.