The Alberta Geological Survey (AGS) collected samples of groundwater for �4C-age dating at three sites within the Athabasca Oil Sands (in situ) Area of Alberta. Each site has a nest of piezometers completed at various depths in Quaternary or Quaternary-Tertiary aquifers. Not all of the piezometers at each site were sampled for �4C-age dating, however. The three Quaternary intertill/intratill aquifer water samples at the first site possess ages of 1558 � 91 radiocarbon years at 41 m depth, 2402 � 110 radiocarbon years at 76m depth and 2532 � 58 radiocarbon years at 120 m depth. A basal Quaternary aquifer at a second site has a calculated age of 30 880-� 257 radiocarbon years at a depth of 158 m below ground. A groundwater sample from a Quaternary-Tertiary buried channel aquifer water sample at a third site has a calculated age of 11 186-� 79 radiocarbon years at 230 m depth.