Abstract: Hydraulic structures which contain surface water, control floods and create storage reservoirs are designed for optimum water use. The stored water, due to high potential hydraulic head seeps through the porous foundation of the structures towards downstream. Seepage in one of the most important design challenges for small and large dams. Regardless of the type of dam. One can say that much of the activities involved for design construction and operation activities and a significant part of the costs for design , construction and operation of water control structures is related to seepage control. Measured the seepage rate for stability analysis of hydraulic structure under various hydraulic conditions is of high necessity. Principles of seepage calculation are based on flow equations on porous environment. This investigation uses finite elements method with three nodes triangular elements for numerical differential equation solving steady flow and drawing flow network downstream of the hydraulic structures. This is carried out under porous environmental conditions in different parts in order to calculate the hydraulic head pressure as well as seepage rate under the hydraulic structures in question. The main focus of investigation is on the foundation of Dez regulating dam which has incorporated cut-off wall and impervious blanket zones. Results indicate that the proposed model was able to calculate the exact rate of seepage flow and flow network under the hydraulic structures in questions.