Geothermal fluids of the Ojo Caliente area discharge from a northeast trending normal fault that juxtaposes Precambrian metarhyolite and Tertiary sediments. An electrical resistivity survey shows that the fluids emerge from the fault and flow as a plume of thermal water into cold aquifers east of the fault. Geochemistry of fluids indicates a maximum reservoir temperature at depth of 80/sup 0/C with no suggestion of high temperature isotopic exchange between water and reservoir rocks. From this data, it is believed that the Ojo Caliente system is suitable only for small-scale direct use geothermal applications.