The Bar dams, in Iran, were constructed to produce a water reservoir outside the main riverbed. However, inadequate geotechnical studies before constructing resulted in seepage miscalculations and delays in operating of the project. To correct the mistakes made in the preliminary studies as well as in the design of the dam, complementary geotechnical tests were conducted during construction. In the present study, upon presenting a brief description of the project and of the preliminary and complementary tests, fundamentals of the numerical finite element modeling are discussed. Based on the results obtained from the seepage analysis, the annual seepage from the reservoir is subsequently estimated. The obtained results shows: the current seepage exceeded that set forth in the project goals. Also, it is possible that internal erosion and the sliding would occur at the downstream alluvial foundation one of these abutments, making the reservoir unstable as a whole. In order to, therefore, providing the project goals and maintaining the stability of the reservoir, appreciate remediation is necessary

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