In most of the western United States, mineral industry waste facilities are separated from the groundwater table by hundreds of feet of unsaturated sands, silts, and clays. Often considered an advantage, because of the slow movement of fluid in the unsaturated zone, these layers can cause problems because by the time contamination is discovered, significant amounts of contamination may have accumulated, and may continue to pollute the groundwater long after the source of contamination is shut down, reclaimed, or removed. Early detection and quantification of vadose zone contamination is central to groundwater protection, yet no reliable remote-sensing technique exists for vadose zone mapping. The research reported here tested the accuracy and resolution of complex geotomography, a new and advanced subsurface imaging technology. The method uses subsurface conductivity (related to fluid salinity in the saturated zone) and dielectric constant (proportional to moisture content and fluid chemistry in the vadose zone). The images are valid at high or low frequencies, and in the earth, where complex, high-contrast anomalies render other approaches inappropriate. Computer simulations showed that the complex geotomography algorithms can provide accurate reconstructions even under the most rigorous theoretical testing. The required electromagnetic amplitude and phase measurements could be made in a mine environment and the measurements used to provide accurate images of effluent location and movement.