Sny Magill Creek IA 01-YEL-430

Assessment Comments

Assessment is based on (1) results of at Sny Magill project sites monitored for water quality, fish, macroinverts, and habitat at varying frequencies and (2) a DNR summary of trout reproduction.

Basis for Assessment

Results of water chemistry and biological monitoring from 1996 and 1997 were reviewed.  During this period there were no violations of the d.o.  standard.  Earlier reports of low DO have not been explained.  Biological monitoring continues to indicate support of a good quality aquatic community of benthic macroinvertebrates and fish.  B(CW) aquatic life use assessment level was upgraded to FS from FS/T due to extensive implementation of agric.  BMPs in the watershed and monitoring evidence.  Relatively low total numbers of forage fish at monitoring sites in Sny Magill Creek and North Cedar Creek in 1995-1997 surveys have not been explained.  A herbicide spill which occurred May 19, 1995 was suggested as a possible cause.  However, some of the sites having low numbers of fish are located upstream from the spill area, and the benthic macro- invertebrate community was apparently not affected by the spill.