Daniel took the portion of the property with the hot springs (where the townsite was eventually built), whereas James preferred the open grazing lands.

[3] In 1882, the two published an advertising brochure titled, El Paso de Robles Hot and Cold Sulphur Springs and the Only Natural Mud Baths in the World.

[3] In 1904 the Paso Robles Hot Sulphur Company was formed by 12 investors to build a bathhouse for locals and to develop a spa for tourists and guests.

The pH is 6.85 and the primary mineral content of the water is Calcium and Magnesium carbonate-chloride with precipitates of sulfur, iron sulfide and barite.

[6][8] In 1889, the spring water was purported to heal "acute and chronic rheumatism, articular affections, scrofula, blood, glandular and cutaneous diseases."

It was also claimed that the water "proved highly beneficial" for catarrh of the naso-pharynx, engorgement of the pelvic organs as well as leucorrhoeal [sic] discharges.