A warm spring at the present site of the Nevada State Maximum Security Prison was used in a bathhouse on the site of Curry's Warm Springs Hotel, which was used for Nevada's first territorial legislature session in 1861 (Guy Rocha, Reno Gazette Journal, 8/18/2002). The Warm Springs Hotel was in operation adjacent to the old State Prison in 1867 (Gillis, 1868). In 1983 the flow from a spring at or near this site issued in alluvium inside an abandoned greenhouse just west of the main gate of the prison. The flow was probably only a few liters/minute at the surface although it could have been greater in the shallow subsurface. The maximum temperature measured at that time was 30°C (L. Garside, unpub. information, 1983). A water well at the Carson City Sewer Treatment Plant, 500 m or more east of the spring at the prison, is reported to be 60 m deep and have a water temperature of 32°C (Trexler and others, 1980, p. 25) Another(?) well there is reported to be 82 m deep and have a temperature of about 21°C, based on water well records in the office of the Nevada Division of Water Resources (L. Garside, unpub. information, 1983). The spring is apparently along the trace of a N15°E fault which separates Pliocene sandstone from alluvium there (Bingler, 1977).
The 21°C water from the the sewer plant well probably should not be considered anomalously warm for this area, although the well does produce warmer water than most cold-water wells in the Carson City area. However, the 32°C water from a different(?) well is clearly anomalous. Possibly the geothermal groundwater in this well results from mixing of somewhat warmer water rising along north-striking faults to the east (see Bingler, 1977) with colder groundwater in the shallow alluvium. This situation would be analogous to the fault-related spring at the prison. Szecsody and others (1984) also suggest mixing of thermal and cold waters in this area, based on stable isotope data; 14C and tritium data on the warm water at the prison suggest the water is between 30 and 500 years old (Szecsody, 1982). If these interpretations are correct, circulation to depths great enough to warm this water must be fairly rapid. Recharge in this area is probably by infiltration from the Carson River (Szecsody, 1982). An area of anomalously warm groundwater is projected to the west of the prison about 1.5 km. based mainly on a water temperature of 28°C (Garside, 1994) from the Carson City No. 4 well (184 m deep). Contours of groundwater temperature (Szecsody, 1982) suggest that the area of warm groundwater may extend along the northwest flank of Prison Hill as well. As described below in the section on the Pinyon Hills area, that area is believed to be separate from the area of thermal groundwater at the prison.