West Okoboji Lake - Main Basin South IA 06-LSR-1653

Assessment Comments

Monitored in 1990 by ISU as part of the Clean Lakes Classifcation study; in 1993 for surveys of Water Supply Reservoir (Miller & Kennedy 1993).

Basis for Assessment

Assessment from the 1992 report (FST) was changed to FS for the following reasons:  (1) BPJ of DNR Fisheries, (2) results of monitoring in 1990 that show average levels of secchi depth, total-P, chl-a, and TSS are much better than overall averages for SPOLs sampled in 1990 and 1992.   Levels of total-P and secchi depth were better than the overall means +/- 1 SD; other parameters were near the upper end of this range.   These data show that the lake has some of the best water quality of any of the SPOLs in Iowa.   Lake was monitored on March 2, 1993 at the inlet and at deep location for 7 ag herbicides in water and sediment.   According to Miller and Kennedy (1993: 53), low levels of atrazine and metolachlor were found in water from the inlet and the deep area.   Additional monitoring is necessary to determine levels of herbicides in summer.   Because levels of atra zine in water were < 1/2 MCL, DW uses were assessed as FS.