Twelve Mile Creek Lake IA 05-GRA-1367

Assessment Comments

Basis for Assessment

Fishable uses were assessed as "fully supported / threatened" (FST), drinking water uses were assessed as "fully supported" (FS), and swimmable uses were "not assessed" for the following reasons:  (1) BPJ of DNR Fisheries suggest that desig.  uses are FST; (2) results of monitoring show that average levels of secchi depth, chl-a, TSS, and total-P are all much better than overall averages for the 86 SPO impoundments sampled in 1990 and 1992 with average levels of TSS and total-P better than the overall average +/- 1 SD; (3) lake does not have problem with fishkills; (4) lake supports one of the highest levels of fishing of any SPO impoundment in Iowa; (5) lake has one of the lowest sedimentation rates (1.1 cm/yr) and longest life expectancies (404 years) of any SPO impoundment in Iowa.   Although lake is desig.  for swimmable use, lake does not have a beach & swim use reported as zero by Bachmann et al.  (1994).   A winter study of pesticides in Iowa water supply reservoirs (Miller and Kennedy 1993) showed that few pesticides at very low levels occurred in this lake.