Tuttle Lake (a.k.a. Okamanpeedan Lake) IA 04-EDM-975

Assessment Comments

Assessment is based on results of (1) lake monitoring and (2) surveys by IDNR Fisheries Bureau.

Basis for Assessment

Swimmable uses were assessed as PS & fishable uses as NS for the following reasons:  (1) BPJ of DNR Fisheries, (2) results of monitoring in 1990 show that averages of secchi depth, chl-a, and TSS are worse than overall averages for the 116 SPOLs sampled in 1990 and 1992 +/- 1 SD; the average level of total-P is worse than the overall average but is within 1 SE of the overall mean; (3) lake has relativley high sedimentation rate 1.4 cm/yr for a natural lake; (4) fishkill frequency is 14%.  Data from Bachmann et al.  (1994) suggest that this lake has a nutrient enrichment problem that is related to lack of sufficient depth to allow thermal stratification.   DNR fisheries considers lakes with winterkill frequency > or = 1 in 7 years (14%) as not supporting fishable uses.