Hydrogeology is known to have important implications to Coalbed Methane (CBM) exploration and development. The lower the regional permeability, the greater the potential to have a pervasive, underpressured gas system and the lower the chance of encountering free water. Therefore, the occurrence of such systems can have a profound impact on the gas contents of the coals, depressuring and water handling and disposal. The objective of this project is to determine the regional pressure systems and to outline the regions of pervasive, underpressured gas for six different hydrostratigraphic units (HSUs) in the upper Cretaceous of southern Alberta.