The objective of the survey in the SW GAB was to assess the TEM method for providing extensive information on leakage from the aquifer cheaply and quickly. The survey covered 57 line km in 2 weeks, which compares favourably with most ground geophysical methods. The results indicate 2 thick, strong conductors intercalated with three resistors. Since these layers appear to bear no relation to stratigraphy, it is anticipated that both lateral and vertical resistivity variations indicate changes in fracture patterns, and in the salinity of the groundwater. It seems probable that there is a relationship between these parameters and upward leakage from the aquifer. It is recommended that follow-up work concentrate initially on defining this relationship.