Des Moines River IA 04-UDM-1211

Assessment Comments

Basis for Assessment

Had 1 of 18 samples exceed Class A WQC for fecal coliforms (=6% viol = FS).   Had 1 of 8 samples exceed Class B WQC for copper (12% viol) and 8 of 9 samples for mercury (89% viol).  As stated elsewhere, no apparent sources of these metals exist; thus disregard for 305(b) reporting.   No other Class B WQC excceded; thus assess as FST.   Four of 68 samples analyzed for nitrate excceded Class C WQC of 10 mg/l as N (=6% viol).   Both mean (5.94 mg/l) and median (5.54) NO3 concentrations were < the Class C criterion; thus assess as FS.   Due to rel.  low levels of NO3, decided not to consider installation of NO3 removal system at DM water works as a cause for impairment on this seldom-used intake (instal.  of the NO3 removal system, however, should be considered an impairment for the Raccoon R.  dstr from Van Meter).