Dipole-dipole Resistivity surveys were conducted at Roosevelt Hot Springs KGRA. Three different dipole spacings were used; 99km of traverse line were surveyed with 100m dipoles, 50km with 300m dipoles, and 44km with 1km dipoles. The objectives of the Resistivity surveying were to detect and delineate regions of low Resistivity associated with fracturing, brines, high temperatures, and clay alteration. The Resistivity of rocks that are typical of hydrothermal environments is due to two main conduction mechanisms: (1) electrolytic conduction through pores and fractures; and (2) surface conduction due to a thin zone of cations attracted to those mineral surfaces with net negative charges (especially clay minerals). For saturated rocks, the Resistivity due to electrolytic conduction is a function of the effective porosity of the fractured rock, of the temperature, and of the salinity of the fluid filling the pores and fractures. The Resistivity decreases as the effective porosity, water saturation, salinity, and temperature increase. The presence of clay minerals and pyrite will also decrease the Resistivity