The paper presents the results of monitoring electrical properties of the soil of the body of the earth-fill dam of the Karolinka water reservoir in the fourth year after its reconstruction ended. Monitoring was carried out using the Z-meter device applying the electric impedance spectrometry method with the focus on seepage through the earth-fill dam of the water reservoir. Information about the changes that occurred in the dam body before and after the implementation of the measure (the construction of a cut-off wall when the dam was reconstructed in 2013) was obtained by monitoring the changes of the electrical resistances of the soil of the dam with time.