Rock Creek IA 02-CED-586

Assessment Comments

Stream use assessment in Mitchell County.

Basis for Assessment

Used results of the July 1992 DNR stream use assessment to assess support of the Class B(WW) aquatic life uses as FST due to (1) habitat score (24) better than the overall median score (22) for DNR stream use assessments, (2) fish score (12) equal to the 75th percentile score for stream assessments made with electrofishers, (3) indications on field sheet of diverse substrates, only isolated channel alterations, and relatively stable banks.   Lower reach of Rock Creek also sampled in August 1982 as part of ISU fish survey (JRO-78-1982); at last bridge before confl w/ Cedar R.   Twenty fish species from 4 families captured, including state-threatened black redhorse and several rare/pollution intolerant species (e.g., Ozark minnow, rosyface shiner, and rainbow darter).  Sample site had excellent aquatic habitat:  high quality riffles of broken limestone and relatively deep pools.   Continued support of the aquatic life uses is threatened by pasturing of riparian zone.