The subglacial electrical environment is surprisingly complex owing to the variety of processes that promote spatial and temporal variability. Possible sources of variability are the chemical evolution of subglacial water and the structural and morphological evolution of the drainage configuration. Such changes contribute to changes in the apparent resistivity of the glacier bed. Less obvious, but possibly more interesting, are those electrical phenomena associated with the natural transport of water and charge in the subglacial drainage system. Streaming potentials are generated by water flow through subglacial sediment, and these potentials are closely associated with the subglacial water pressure field. To explore these effects, we have monitored induced and natural electrical responses in the deforming material beneath Trapridge Glacier, Yukon, Canada. Several arrays of electrodes were placed at the ice-bed interface, and data were recorded over a period of several years. Data from these experiments indicate that natural potentials can be used to monitor water pressure gradients and that the bulk resistivity of the glacier bed can be altered by changing the hydraulic regime. We present evidence that temporal variations in streaming potentials can indicate fluctuations in subglacial water flow rate and that spatial variations can be related to variations in bed elevation, water pressure, and hydraulic connectivity. ¿ 1999 American Geophysical Union