North Cedar Creek IA 01-YEL-431

Assessment Comments

Assessment based on results of (1) IDNR/UHL biocriteria sampling data in 2000 and (2) water quality and biological monitoring conducted in 2000-01 as part of the Sny Magill / Blood Run project.

Basis for Assessment

SUMMARY:  The Class B(CW) aquatic life uses remain assessed (monitored) as "fully supported" based on results of biological monitoring conducted in 2000 and on results of ambient water quality monitoring conducted from 2000-2001.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream reach.   The sources of data for this assessment are results of (1) IDNR/UHL biological monitoring conducted in 2000 as part of the stream biocriteria project and (2) water quality monitoring conducted at IDNR station 15220003 from January 2000 to September 2001 as part of the Sny Magill Creek Nonpoint Source Pollution Monitoring Project.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream reach.  

EXPLANATION:  The assessment was based, in part, 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 5/8.   The aquatic life use support was assessed as Fully Supporting/Threatened (=FS/T), 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.  

Results of the chemical monitoring conducted on this stream segment in from 2000 through 2001 as part of the Sny Magill Creek Nonpoint Source Project also suggest "full support" of the Class B(CW) uses.   No violations of Class B(CW) water quality criteria for dissolved oxygen or temperature occurred in the approximately 90 samples analyzed during this period.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment.  

For more information on the Sny Magill Creek Nonpoint Source Pollution Monitoring Project visit the DNR-Geological Survey Bureau web site at http://www.igsb.uiowa.edu/inforsch/waterag.htm.