Abstarct: The purpose of this research is to evaluate the water loss from foundation and embankments of Gotvand dam and present suitable solutions aim at decreasing these water losses. To achieve this, firstly, effective factors in seepage and usual methods for reducing it, in earth dams have been evaluated. Then, with the aid of field investigations and geotechnical studies, sub surface condition of the embankments of the dam was assessed. In addition, by undertaking Lujon and Lofran tests, permeability of foundation and embankments materials and their behavior under different pressures, have been studied. The results of injection grout test and seepage shows that by choosing suitable methods for injection such as correct percentage of cement mixture, optimum injection pressure and also using suitable additives, seepage of Gotvand dam can be reduced to necessary amount. Other topics evaluated in this study include behavior of stone mass of Gotvand Dam against water pressure test and its classification and the properties and role of pressure in controlling the behavior of stone mass. The results of this research have led to the development of some protocols that help in the selection of the types of drilling and injection as well as correct effective pressure in designing injection screen from inspection gallery and within different phases of dam structure.