Zooplankton abundance and composition are one of the most important factors which affect the food web in aquatic ecosystems. The purpose of this study was to determine the water quality of Bafa Lake in Turkey, based on zooplankton communities. As the study case, Bafa Lake is one of the biggest lake in Turkey, and the lake is quite rich in terms of biodiversity. Bafa Lake is the under effects of domestic, agricultural and industrial wastes that accumulate and cause the deterioration of ecology in the lake by Büyük Menderes River. With this purpose, 8 sampling sites were determined and zooplankton samples were collected monthly for two years. TSINRot index and various versions of diversity indices were used to determine the water quality and ecological status of Bafa Lake. To determine similarities between the stations, the stations were clustered by using UPGMA based on zooplankton fauna. By applying Pearson Correlation, correlations between the indices based on zooplankton fauna were assessed. With the identification of collected zooplankton, a total of 73 taxa which belong to groups of Rotifera, Cladocera, Copepoda, and Meroplankton were detected. As a result of similarity analysis, most similarity values were obtained between stations 1, 2 and 8, respectively. According to TSINRot index, Bafa Lake has got a eutrophic ecological state while according to all versions of diversity indices, Bafa Lake has got the α-β mesosaprobic ecological state.