The study investigated the interplay of factors influencing the occurrence of Uroglena sp. blooms in surface water, particularly during the spring season. While Uroglena sp. typically demonstrates a propensity for blooming during the spring season, diminished population density was documented, underscoring the influence of pertinent environmental factors. To study the determinants, surface water samples collected for 3years were analyzed for general water quality parameters, coexisting microalgae species, and total bacteria. Key determinants were found to include the ratio of dissolved nitrogen to dissolved phosphorus (DN: DP), temperature, bacterial density, the presence of Dinobryon sp. (golden algae) and Microcystis sp. (cyanobacteria). The findings indicate that factors such as DN:DP ratios and temperature variations intricately modulate Uroglena sp. bloom by affecting microbial dynamics, notably competitive interactions. The findings of this study offer further scientific insight into addressing seasonal occurrences of fishy odors in water reservoirs, with particular relevance to the spring season.