The nonlinear behavior and crack propagation in concrete dams, particularly at spillway sections where section variations can induce excessive local stresses, pose significant challenges for designers. While many designs rely on 2D models due to their simplicity and reduced computational demands, this common approach may underestimate stress concentrations and potential damage at critical spillway sections. This study undertakes a comparative analysis of 2D and 3D simulations of a concrete gravity dam using the finite element program ABAQUS. Our findings indicate that 3D simulations more accurately detect damage at stress concentration points, underscoring the importance of employing rigorous 3D models for complex sections of concrete gravity dams to ensure structural integrity and safety.