Chemical analyses of ground water related to geothermal investigations in the Teton River area, eastern Idaho

Water samples were collected from 31 wells and springs in eastern Idaho and western Wyoming to help evaluate the potential geothermal resources in the Teton River area, Idaho. The water analyses included the common anions and cations, oxygen-18, deuterium, and several minor elements. Actual temperatures of the sampled thermal waters ranged from 23° to 49°C. Estimated aquifer temperatures, as derived from geochemical thermometers, ranged from 45° to 145°C based on silica concentrations and 45° to 205°C based on sodium-potassium-calcium ratios. Using the cation thermometer, two analyses indicated aquifer temperatures that were lower than the actual measured temperatures. Estimated temperatures using a mixing-model method ranged from 205° to 320°C, the higher temperature being of questionable value. The different methods used to estimate aquifer temperatures showed little correlation. On the basis of isotope data, the warm waters may be of local meteoric origin and have not been heated enough to react significantly with the aquifer rocks, or they originated as precipitation at high altitude and great distance from the area.