Warm springs and warm water wells are distributed over the southern third of the Amargosa Desert. The temperatures reported are mostly less than 32°C, and many wells have temperatures no more than 5 to 8°C above the mean annual air temperature. The thermal springs, known as Big, Ash Meadow and Deep Springs (SW¼ NE¼ Sec 19, T18S, R51E), are concentrated in the vicinity of Ash Meadows and the Death Valley National Monument and are almost certainly related to one or more north- and northwest-trending faults along the east side of Ash Meadows. Spring temperatures are about 24-34°C, with discharge ranging from 3785-6711 L/min (Hughes, 1966; Mifflin, 1968; Center for Water Resources Research, 1973), and extensive travertine deposits are present at some springs (Naff, 1973). The source of the spring waters is apparently carbonate aquifers that are exposed in an area to the northeast (Dudley and Larson, 1976). A number of subspecies of endangered pupfish live in the waters of several of the Amargosa Desert warm springs.