This report presents a description of the hydrogeology of the Wintinna coal deposit proposed mine site area, and of the investigative work performed to acquire specific data on aquifer properties and groundwater behaviour. Two production bores were drilled into the major sandstone aquifers to depths of around 160 m, and these were pump tested for 24 hours and the results analysed and interpreted, with input from 6 other monitoring wells either purpose drilled/constructed or already present and converted to act as piezometers. Permeability testing of the Upper Permian coal measure rocks by downhole packer methods was carried out in two existing fully cored geotechnical test holes, and groundwater quality analyses were also done.