Hot springs near the town of Carlin lie near the south end of the Carlin Trend structural zone (Zimmerman and others, 1991, p. 56) Thermal waters in the 24 to 60ºC temperature range are found in deep workings and drill holes for over 40 km along the Trend. The higher temperature waters have been observed in developmental drill holes and water wells along several major structural zones in the Blue Star (~Sect. 4, T35N, R50E) and Bootstrap (~ Sec. 3, T36N, R49E) districts, at depths of 244 to 762 m. Vertical fracture flow of thermal waters from the locally artesian regional carbonate aquifer is reported at the Post-Betze, Purple Vein, and Bootstrap gold deposits northwest of Carlin. Isothermal conditions at a maximum temperature of 60ºC occur below producing fracture zones at depths from 335 to 457.2 m below the original, pre-mining surface (Zimmerman and others, 1991, p. 56).
Two hot-spring areas are located 2-4 km southwest of the town of Carlin in SE¼ Sec. 33, T33N, R52E and in the SE¼ SW¼ Sec. 5, T32N, R52E. The temperatures have been reported as 78.8°C F or boiling (Mariner and others, 1974; Bradberry and Associates, 1964) and warm (Bradberry and Associates, 1964), respectively. Trexler and others (1982) reported a temperature of 82°C for the Sec. 33 spring (their Carlin Hot Spring) and 24-35°C for the Sec. 5 spring (their Long John Warm Spring). Hot water was encountered in two wells drilled within 0.5 km of the hot springs. An estimated thermal aquifer temperature (Na-K-4/3Ca) is near the spring temperature of the northern spring (Mariner and others, 1974).). The Carlin High School (NW¼ SE¼ Sec. 27, T33N, R52E) used 31°C geothermal fluid from a 280-m well from 1986 to 1992 in a closed-loop space heating system. The well was abandoned in 1992, apparently in part because of scaling problems with iron and manganese. Gravity data suggest the geothermal springs and wells are associated with a concealed northeast-striking fault.