Cal. Public Resources Code § 3742.2

Any person having drilled a well or wells on state, federal or private lands which are producing or, according to the supervisor, are capable of producing geothermal resources, may, at any time, apply to the supervisor for a certificate of primary purpose. When the supervisor determines that such well or wells are primarily for the purpose of producing geothermal resources and not for the purpose of producing water usable for domestic and irrigation purposes, the supervisor shall issue a certificate of primary purpose to such person. Such certificate shall establish a rebuttable presumption that such person has absolute title to the geothermal resources reduced to his possession from such well or wells. Such presumption may be rebutted only upon a showing that the water content of the geothermal resources is useful for domestic or irrigation purposes without further treatment thereof, but not by virtue of any production of such water as a by-product incident to the production of the geothermal resources.