Procedures and apparatuses for determining the integrity of a geophysical barrier are provided. In particular, an electropotential gradient is established across the barrier in an attempt to drive ionic species through the barrier. The resulting ionic transport results in a current which can be measured between the electrodes, and which can be correlated to the integrity of the barrier. The location of a leak in the barrier can be determined by the use of an electromagnetic sensor which detects an anomaly in the flux field associated with the current.