Grannis Creek IA 01-VOL-322

Assessment Comments

Assessment is based on a 2006 summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau.

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 “HQ” (high quality) 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) coldwater aquatic life uses remain assessed (monitored) as "fully supported" based on the May 2006 summary of trout reproduction in Iowa streams as prepared by the IDNR Fisheries Bureau.    Fish consumption uses remain "not assessed."  

EXPLANATION:  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, Grannis 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.