Subsurface injection of CO 2 creates pressure build-up in the geological formation and the formation water is displaced laterally within the storage formation and/or vertically through the top seal into overlying formations. Numerical simulations of industrialscale CO 2 injection taking into account variable-salinity water indicate that the overall potential for brine displacement resulting in significant salinization of fresh groundwater resources is low. Although the radius of pressure impacts can be on the order of 100 km, the resulting formation water flux decreases rapidly in the far-field of the injection site where the displaced volumes of saline formation water are small.