Data on hydrogeological and lithological characteristics of geological formations are obtainable at every dam site. In practice, it is essential to examine the data using an engineering-based approach such as geostatistical methods. Specifically, it is important to recognize the principal factors that significantly control hydrogeological characteristics, such as Rock Quality Designation (RQD) and average hydraulic conductivity of the rock mass (Lugeon value). In this study, the statistical properties of these parameters are examined as functions of depth, lithology and the spatial distribution of the data points. The results of this study show that the spatial distribution and lithology are the main controls. Using this approach one can determine the most permeable rock formations, potential karst locations and the areas that may warrant more extensive study. The results of stochastic simulation could be extensively enhanced by considering the spatial distribution of hydrogeological characteristics.