East Fork Wapsipinicon River IA 01-WPS-409

Assessment Comments

No information available upon which to base an assessment.

Basis for Assessment

NOTE:  Following their review of Iowa's 2004 Section 303(d) list, EPA--in their November 2005 decision document--proposed adding-back this segment of the East Fork Wapsipinicon River based on impairment of aquatic life uses suggested by 1995 biological data generated as part of the IDNR/UHL biocriteria project.   IDNR staff determined, however, that, due to segment splitting conducted for the 2002 reporting cycle, (1) the results of the 1995 biological assessment were appropriately reassigned to the most upper segment of this stream (IA 01-WPS-0190-6) (which is where the 1995 biological sampling was conducted) and (2) that the 1995 assessment results should have been deleted from this segment (IA 01-WPS-0190-3).   Thus, as noted in IDNR’s December 19, 2005 letter to EPA, the original 2004 assessment for segment IA 01-WPS-0190-3 was in error, and this waterbody should not be added to Iowa’s 2004 Section 303(d) list.   Based on this information, the 2004 assessment for segment IA 01-WPS-0190-3 was corrected in January 2006.  

The original (erroneous) 2004 assessment is appended below:

"SUMMARY:  The Class B(LR) aquatic life uses are assessed (evaluated) as "partially supporting" based on results of IDNR/UHL biological monitoring conducted in 1995 as part of the stream biocriteria project.   The aquatic life uses of this segment were not assessed for the 2002 reporting cycle due to age of the data.   These data, however, remain current enough (less than 10 years old) to develop an "evaluated" (I.e., lower confidence) assessment.    No causes or sources of the impairment were identified in historic assessments."

"EXPLANATION:  As stated in the assessment developed for the 2000 reporting cycle, the assessment of the Class B(LR) aquatic life uses was based on data collected in 1995 as part of the IDNR/UHL stream biocriteria development project.   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 that were collected in the stream sampling reach.    The biological metrics were combined to make a fish community index of biotic integrity (F-IBI) and a benthic macroinvertebrate index (BM-IBI).   The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum)-100 (maximum).   The F-IBI score was 41 (fair), and the BM-IBI score was 48 (fair).   The aquatic life use support status was assessed as partially supporting (=PS), based on a comparison of the F-IBI and BM-IBI scores with biological assessment criteria established specifically for the 2000 Section 305b report.   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-1998."