The loads acting on the pressure face of hydraulic structures from the water mass of the reservoir during earthquakes are usually set in the form of a diagram of the coefficients of the added mass of water, while the hydrodynamic pressure of water along the height of the pressure face is distributed in proportion to the diagram of the obtained coefficients. The paper presents a solution to the problem of hydrodynamic water pressure on the pressure face of an earth dam at slope angles from 0 to 75 degrees (with respect to the vertical). Construction of isolines of the streamline function distributionψ (x, z) in the computational domain was carried out in PC MATLAB. Solution Δψ = 0 allows to build isolines of the distribution of the hydrodynamic pressure function φ(x, z) in the computational area. The paper presents hydrodynamic grids and graphs that make it possible to construct a diagram of the added mass of water for the entire range of emplacement of the upper slopes of dams. The developed method for solving the problem of hydrodynamic water pressure on the pressure face of the dam can be applied to any shape of the slope profile of the dam.