Assessment Comments
Assessment is based on results of monitoring conducted by Iowa State Univ. as part of the ACOE's Des Moines R./Saylorville Res./Red Rock Res. water quality study.
Basis for Assessment
Had no violations of the Class A WQ criterion for fecal coliform bacteria in the 13 non-flow affected samples collected during summers of 1996 and 1997 (=FS). Levels of fecal coliforms ranged from 1 to 90 orgs/100 ml. Had no violations of Class B(WW) WQ criteria for conventional pollutants in the 46 samples collected over the 1996-97 period. Class B(WW) WQ criteria for three toxic metals, however, were exceeded during the Oct 94-Sep 97 period: 2 of 12 samples (17%)exceeded the chronic criterion for copper (=NS according to 1998 Section 305(b) Guidelines, p. 3-18); one of 12 samples (8%) exceeded the chronic criterion for zinc (=FS); and 8 of 11 samples (73%) exceeded the chronic criterion for mercury (due to problems with analysis for merucry in water, and based on recommendations of Section 305(b) reporting guidelines, did not use data for mercury to develop this assessment). Levels of pesticides (e.g., dieldrin and chlordane) in composite samples of whole-fish carp collected in 1996 & 97 were all below 1/2 the FDA action levels (=FS fish consumption uses). Problems with gas supersaturation remain: fish kill on Aug. 12, 1997 attributed to this problem.
