In this study, water samples were collected from four different stations in Sarimsakli Dam Lake from May 2001 to June 2002 monthly to determine the trophic situation of lake. Additionally, physical parameters of water such as temperature, dissolved oxygen, electrical conductivity (EC), pH, light permeability were measured in the field and status of surface active substance, sulphur, nitrite, nitrate, total nitrogen, phosphate, total phosphate, oxygen saturation were analysed in Environment Ministry Reference Laboratory. Zooplankton samples were collected with a plankton net mesh size of 55 mu m horizontally and vertically and they were fixed with 4% formaldehyde. The results of the light permeability, basic water quality parameters and dominant zooplankton species indicated that the lake studied was eutrophic. Furthermore, biotic index confirmed this result. The Lake examined in study area was partly polluted with different sources, because the study area is liable to human activities. If the pollution is not prevented, it may endanger the lives of living organisms here in future. Knowledge on the trophic situation of Sarimsakli Dam Lake is not well established; so all of the zooplankton species determined are new records.