Monitoring environmental productivity requires an understanding of the taxonomic composition of phytoplankton communities. The main objective of this study was to investigate the diversity of diatom flora communities in the Sebou basin, which is continuously exposed to various types of pollution. Therefore, it was necessary to monitor the water quality of this basin and conduct a qualitative assessment to understand their dynamics. By analyzing the taxonomic composition of the aforementioned flora population in this basin, we have contributed to the development of a database that compiles the systematic structure of a botanically significant group for the creation of biological indicators. These indicators allow for a highly reliable evaluation of the biological and physicochemical quality of the waters in this basin. The results obtained show the existence of 177 species distributed in 57 genera, 27 families, 12 orders, and 3 subclasses. The subclass of Bacillariophycidae is the most represented, including two genera Navicula and Nitzschia which are the best represented. These same results show that the distribution of species is never uniform in space and that the ecological conditions in which this population thrives allow us to distinguish groups that have been found here and there along the Sebou basin, thus they are ubiquitous species. These species include, for example, Navicula. radiosa, N. trivialis,viridula,Fragilaria gracilis, F. crotonensis, Nitzschia palea, N. dissipata, N. elegantula,and N. angustata. The other group colonizes only a narrow portion of the biotope studied that are therefore categorized as stenoecious species, such as Nitzschia capitellata, N. amphibia, N. clausii, N. filiformis, Frustulia vulgaris,and Pinnularia divergens.