Today, diatoms are being used to assess ecological conditions in surface water bodies around the world. As diatoms occur in almost all the environmental niches, the same group of organisms can be used for comparison of lakes, streams, wetlands, oceans, estuaries, and even some ephemeral aquatic habitats. Diatoms play a significant ecological role and are being extensively used as indicators of water pollution because they are natural inhabitants of the water. The distribution of diatom species in surface water bodies is mainly governed by the physico-chemical composition of the water. It is important to understand which environmental variable can affect diatom growth, assemblage, and distribution. In India, Diatom studies especially for monitoring the environment are yet to gain momentum. The investigations on Lake Diatoms are scanty. Understanding threshold responses in diatom assemblages along environmental gradients is valuable for justifying specific management targets. Thus, a more complete understanding of the taxonomy and ecology of diatoms remains at the foundation of sound science for environmental assessments and advancements in that science.