The determination of critical depth and the position of control sections is important in open-channel hydraulics. Calculation of critical depth in open channels is useful not only for determining the condition of a flow but also for hydraulic design and analysis of experimental and analytical results. In this study, unlike the conventional approaches, an alternative method, based on a genetic algorithm GA , for the calculation of critical depth in conduits is presented. In our model, the governing equations are transferred into an objective function that is then minimized using a GA in order to calculate critical depth. This method does not have the limitations of existing empirical and semiempirical methods and can be used for any prismatic or nonprismatic open-channel cross section. The concepts presented in this paper can be generalized for solving other tortuous hydraulic engineering equations and problems.