Assessment Comments
Assessment is based on: (1) the results of IDNR/UHL biological (biocriteria) monitoring in 2001: 5/8 coldwater biological indicators met the criteria = Fully Supporting (FS) and (2) an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006.
Basis for Assessment
Note: Prior to the current (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 stream segment also remains identified as an “HQR” (high quality resource) water.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses and presumptive Class A2 (secondary contact recreation) uses are "not assessed" due to the lack of data for indicator bacteria upon which to base an assessment. The Class B(CW1) aquatic life uses are assessed (monitored) as "fully supported" based on results of IDNR/UHL biological (biocriteria) monitoring in 2001 and on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006. The biological data are now more than five years old; therefore, this assessment is now considered "evaluated" instead of "monitored". Fish consumption uses remain "not assessed."
EXPLANATION: The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2001 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 5-8 are Fully Supporting (FS), sites that score 2-4 are Partially Supporting (PS), and sites that score 0-1 are Not Supporting (NS). The 2001 coldwater biological indicator score was 5/8. 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 1994-2004 and with assistance from the IDNR Fisheries Bureau.
In addition, based on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006, the Class B(CW1) uses are assessed as "fully supported". According to the updated summary, Catfish Creek is in the group of Iowa coldwater streams that supports natural reproduction of trout. Based on results of surveys by the IDNR Fisheries Bureau, this stream is placed in the category of Iowa trout Streams that exhibit fairly consistent natural reproduction and maintain a viable population of the listed species without any stocking. This assessment is consistent with previous assessments of the ability of this stream to support natural reproduction of trout.
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.
