© Springer International Publishing Switzerland 2016. Dam safety is an issue that affects directly or indirectly all society sectors. Up to now, Mexico does not have a proper federal or state legislation to evaluate dam safety, thus it is difficult to assign liability when total or partial dam failure occurs or to prevent failure by programming cost-effective dam supervision. Dam safety risk analysis by means of numerical simulations has the objective of evaluating the occurrence probability of a phenomenon, or group of phenomena, that affects dam safety. This work is focused on obtaining the overflow probability of the dam “La Esperanza” located in Hidalgo, Mexico. With this purpose, first, a statistical hydrologic analysis using daily maximum rains was conducted to obtain dam inflow as a function of rainfall duration and return periods. Second, different inflow scenarios were simulated to obtain their associated maximum hydraulic head values using the Smoothed Particle Hydrodynamics (SPH) numerical method. Finally, simulation results of maximum hydraulic head reached by water particles were used to calculate the overflow probability. We have obtained a high overflow probability for the “La Esperanza” dam warranting more studies, for this and other dams with similar conditions, given that the hazard potential to populated downstream areas is high.