Indonesia has 147 volcanoes by which approximately 76 are active, including volcanoes in Dieng plateau, Java. Dieng is surrounded by complex volcanic mountainous as the highest plateau in Indonesia. The activity of the volcano affected the formation of lakes in the Dieng plateau, one of them is Cebong Lake. Similar to other lakes in Dieng, Cebong Lake is an important resource for water supply, ecotourism, and irrigation for potato plantation. The multiple drivers of physical parameters of water quality interact across multiple scales affected the diversity of diatom. This study aimed to determine the relationship between water quality and epipelic diatom assemblage in Cebong Lake. The diatom samples were collected from the different sediment surface sites from Cebong Lake to show a diatom distribution associated with physicochemical parameters of water quality. The sediment sample was digested using hot HCL and H₂O₂ 10% to remove organic material, mounted with Naphrax, and identification/enumeration of diatom using a microscope under 1,000 magnification for at least 300 valvae were found. The surface epipelic diatom community was represented by 60 taxa belongs to 27 genera. The diatom indices that represent >70% species from Cebong Lake were IDG, IPS, TDI, IBD. Based on the diatom indices, Cebong Lake was in the b mesosaprobic status. This is supported by the concentration of TN and TP that was in the mesotrophic status. Diatom assemblages from Cebong lake were characterized by the presence of Achanthidium microcephalum, Brachysira brebissoni, Aulacoseira tenella, and Denticula tenuis that were correlated with NH₃. The occurrence of Staurosira psedoconstruens was correlated to the turbidity, DO, and pH. Nitzchia palea was correlated with temperature, while Achanthidium minutissimum, Staurosira construens, and Fragillaria tenera are being closer to each other and were associated mainly with TP. Diatom species had specific tolerance to the environmental parameter and their response in species and communities level had indicated the water quality of the lakes.