To further investigate the transport-diffusion characteristics of pollutants under the condition of lateral water intake, a typical lateral water intake project in southern China was selected as the study case. A three-dimensional hydrodynamic-pollutant transport-diffusion model was established. Then, the impacts of pollutant releases at different vertical and transverse positions on water quality were systematically analyzed. The results showed that, overall, the turbulent kinetic energy at the surface layer was less than that at the bottom layer, but within the recirculation zone, the turbulent kinetic energy at the surface layer was greater than that at the bottom layer. The surface layer diversion width near the water intake was approximately 0.53 times that of the bottom layer. For sudden water pollution events caused by pollutant releases at different vertical positions, the pollutant mass concentration distributions at the water intake exhibited a broad and low-peaked pattern