Assessment is based on results from the DNR monthly water quality monitoring station at Hwy 59 near Shenandoah.
Basis for Assessment
Due to lack of biolgoical information, based the assessment of the Class B(WW) aquatic life uses on results of monthly water quality monitoirng at the DNR station at Shenandoah: no violations Class B(WW) WQ criteria for either conventional or toxic pollutants occurred in the 24 samples collected during the October 1995 to September 1997 period. Although this reach is not designated for Class C drinking water uses, results of pesticide monitoring show no levels of atrazine or alachlor in the 24 samples collected from Oct 95 through Sept. 1997 that exceed MCLs (ranges: atrazine: 0.1-1.7 ug/l; alachlor: 0.1-0.4 ug/l). Data for levels of toxic contaminants in fish are from the 1990 RAFT and are thus considered too old (>5 years) for making "monitored" Section 305(b) assessments. The assessment of support of the Class B(WW) aquatic life uses was developed without the benefit of biological information. Monitoring is needed to determine the status of the aquatic communities and habitats in this reach of river and to determine to what degree the Class B(WW) uses may be impaired. Assessment of the Class B(WW) aquatic life uses was set at FST due to potential impacts of extensive channelization and other impact in the riparian corridor of this stream (e.g., stream bank erosion and removal of natural riparian vegetation).