Reservoirs can get polluted during flood seasons, affecting water quality. A study used a model to identify pollution sources and assess risks to water quality. Nonpoint sources are the main polluters, contributing to nitrogen, phosphorus, fecal coliforms, and turbidity. The risk of water quality issues increases with higher rainfall, especially for nitrogen, phosphorus, and fecal coliforms. The risk is higher at the reservoir inlet than at the dam site, and phosphorus and turbidity levels increase more than nitrogen and fecal coliforms. Biochemical oxygen demand is less affected by nonpoint pollution. This research can help manage water quality during flood seasons.