This hydrothermal reconnaissance of the State of Utah contains temperature-profile data for 30 wells. Most of the wells were small-diameter geothermal-exploration wells. Some were stock, domestic, or irrigation wells. Temperatures were measured using thermistor, 4-conductor cable, and a digital multimeter. Meter readings were in ohms, but were converted to temperature by a calibration graph. The electronic thermometer is capable of an accuracy to 0.01 deg C, and the highest temperature measured was 107.80 deg C in the only well to have measurements of 100 deg C or higher. Because of variations in field conditions, the temperature data in many wells probably is accurate only to 0.1 deg C. Depths below land surface were measured using a sheave and attached counter. (Woodard-USGS)