Assessment Comments

Assessment is based on results from IDNR ambient monthly monitoring.

Basis for Assessment

Upgraded the assessment of support of the Class B(WW) aquatic life uses developed for the 1996 report from PS to FST, with the primary threat being habitat alterations due to extensive channelization.   Results of DNR WQ monitoring near Shambaugh show no violations of Class B(WW) WQ criteria for either toxic or conventional contaminants in the eight samples collected from Oct 93 to Jul 95.   Thus, WQ montoring suggests good water quality in this river reach.   Results of fish contaminant monitoring conducted in 1994 as part of the U.S.  EPA/ DNR Regional Ambient Fish Tissue (RAFT) monitoring program showed that levels of all contaminants in the sample of channel catfish were less than 1/2 of the respective FDA action levels; thus, fish consumption uses were assessed as FS.   Support of the Class C drinking water uses were assessed as FS due to levels of nitrate well below the MCL of 10 mg/l as N:  levels of nitrate in the 8 samples collected from Oct 93 to Jul 95 ranged from 0.6 to 4.7 mg/l as N.   No information is available on levels of pesticides.   Follow-up monitoring is needed to determine the status of aquatic communities and to determine the degree to which the Class B(WW) uses may be impaired.   The assessment of support of the Class B(WW) uses developed for the 1996 report (=PS) was developed without either chemical or biological information.