Silver Lake IA 04-UDM-1229

Assessment Comments

Basis for Assessment

Swimmable uses were not assessed, and fishable uses were assesed as PS for these reasons:  (1) BPJ of DNR Fisheries; (2) results of monitoring show that average levels of secchi depth, chl-a, total-P, and TSS are worse than overall averages for the 116 SPOLs sampled in 1990 and 1992; average levels of secchi depth, chl-a, and TSS are worse than the overall averages +/- 1 SD; (3) lake has a relatively low sedimentation rate (0.8 cm/yr) but has a relativey short life expectancy for a natural lake (189 years); (4) although designated for swimmable uses, the lake does not have a swimming beach, and Bachmann et al.  (1994) report swimming use as zero; (5) lake has a winterkill frequency of 12 percent.   Thus, lake has poor WQ for SPOLs, and organic loads combined with shallowness lead to fishkills that impair fishable uses.