North Bear Creek IA 01-UIA-255

Assessment Comments

Assessment based on 2000 IDNR biocriteria sampling data: 8/8 coldwater biological indicators met the criteria - Fully Supporting (FS).

Basis for Assessment

SUMMARY:  The Class B(CW) coldwater aquatic life uses remain assessed as "fully supported."  Fish consumption uses remain "not assessed."  EXPLANATION:   The assessment was based on data collected in 2000 as part of the DNR/UHL stream biocriteria project.   A series of eight (8) coldwater biological indicators, which reflect stream water quality and habitat integrity, were calculated from the biocriteria sampling data and supplemental IDNR Fisheries Bureau data.   The coldwater biological indicators are based on the numbers and types of coldwater benthic macroinvertebrate taxa and fish species that were collected in the stream sampling reach.   Sites that score 7 or 8 are Fully Supporting (FS), sites that score 4-6 are Fully Supporting/Threatened (FS/T), sites that score 2-3 are Partially Supporting (PS), and sites that score 0-1 are Not Supporting (NS).   The 2000 coldwater biological indicator score was 8/8.   The aquatic life use support was assessed 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 1994-2002 and with assistance from the IDNR Fisheries Bureau.   In addition, based on a 1999 summary of trout reproduction in Iowa streams, and based on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in April 2002, the Class B(CW) uses remain assessed as "fully supported."  According to this summary, this reach of North Bear Creek is in the category of Iowa trout streams that have fairly consistent natural reproduction and are capable of maintaining a viable population for the target trout species without any stocking.   Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.