The many spa resorts in Desert Hot Springs draw their natural hot mineral waters from their own wells in the Desert Hot Springs Subbasin aquifer. The water in this aquifer seeps down through fissures deep into the earth, where it is heated and rises back up through those fissures as superheated steam, warming the water held in the hot water aquifer. MSWD is often asked for maps of the hot water zone and so we have supplied them below. Please note that these maps are 20 to 30 years old, so spas listed on them may no longer exist and exact boundaries and temperature readings may no longer be accurate. At this time, MSWD does not draw or test water from the hot water aquifer and does no mapping of the hot water zone. These existing maps are provided for information requests only.