The geotechnical parameters and permeability of the Bazoft dam site were investigated. The bedrock of the Bazoft dam site belongs to the Asmari and Jahrum (Eocene, Oligocene and Miocene) formations. Rock mass rating (RMR) and geological strength index (GSI) classification systems were used to evaluate the dam site. Physical, mechanical and dynamic tests were performed on samples in a rock mechanics laboratory. Shear strength parameters and geotechnical parameters of the rock mass were determined. The results of Lugeon tests for determining rock mass permeability were in the range of 10–30. Based on the RMR, the dam site is located in the ‘good’ category. Finally, the relationship between Lugeon, the number of joints and rock quality designation (RQD) of the rock mass was evaluated using statistical analysis for 24 exploratory boreholes with a total length of 3400 m. The values of these parameters were determined and analysed using equations, tables and reports in sections of 5 m along the borehole. The results showed that the relationship between Lugeon with RQD and the joint number is an exponential equation with a good correlation coefficient. Multiple linear analysis also showed high accuracy of the estimated Lugeon based on RQD and joint number.