Warm groundwater has been encountered in nearly 50 shallow domestic water wells in the Pinyon Hills subdivision, located in the vicinity of Pinyon Hills Drive (E½ Sec. 23, T15N, R20E) in the low hills just east of the Carson River. Water temperatures range from 25°C to 46°C in wells 38-150 m deep (Trexler and others, 1980; Garside and Schilling, 1979). Flynn and others (1980) reported temperatures as high as 60°C. There is no surface discharge in the area, and the water quality is poor. The wells in this area were not drilled for geothermal applications, but rather for water for drinking and other domestic uses. Some residents of the area have considered or attempted space-heating applications (Trexler and others, 1980), but the temperatures are relatively low for direct use.
The area of thermal wells is elongate in a northerly direction along Pinyon Hills Drive, and is on line with a northerly striking fault shown by Bingler (1977) about 1.5 km to the north (McKinney, 1976; Flynn and others, 1980; Trexler and others, 1980). The area of potential thermal groundwater can be extended to the vicinity of that fault based on thermal groundwater contours developed by Szecsody (1982, p. 138). No data area available on the age of the water, but the Pinyon Hills thermal water is isotopically depleted, similar to the Carson Hot Springs water, suggesting the Pinyon Hills water was recharged during a colder climate, possibly 12,000-14,000 years ago (Szecsody, 1982, p. 175). Apparently the area of thermal groundwater is separate from the one in the vicinity of the State Prison, as a temperature gradient drill hole drilled west of the southern end of the Pinyon Hills geothermal area encountered cold groundwater to about 153 m (Trexler and others, 1980).