Franciscan missionary and explorer Juan Crespí, who was the diarist for the expedition, mentioned the artesian springs in his 1769 diary.

The springs were a gathering place for several thousand years for the Tongva, Chumash, Tataviam and other Indigenous tribes.

[3] Rancho Los Encinos, the land encompassing the springs, was originally granted by the Spanish king to a veteran of the Portolá expedition named Juan Francisco Reyes, then regranted to the San Fernando Mission in 1797, and then finally, after secularization, in 1845, one square Spanish league was granted by the Mexican government to Ramon, Francisco and Roque, who are traditionally believed to have been Mission Indians.

Land case records state that de la Osa had sought out the "Native Americans who owned Encino prior to him in exchange for the right to purchase the rancho from them.

[6] De la Osa claimed that the springs on the property were "both cold and warm, the latter possessing medicinal qualities.

[9] In 1925, a Mexican worker at the site discovered a 20-inch (51 cm) grinding mortar made of volcanic basalt, and a possible burial ground west of the springs.

[12] The springs have been under the purview of the California State Parks and Recreation department since 1949,[13] and continue to feed the reservoir (alternately called an artificial lake or "fishpond") that was built by Garnier in the 1870s.

The report stated that the site was known as the "old Amestoy Homestead", and mentioned that a swimming pool and dance hall were being constructed at the "famous hot spring".

The mineral content was recorded as including sodium, calcium, sulphate, chloride, carbonate, silica, and trace amounts of potassium, lithium and phosphate.