As used in this chapter, unless the context requires a different meaning: “Board” means the State Water Control Board. “Correlative right” means the right of each geothermal owner in a geothermal system to produce without waste his just and equitable share of the geothermal resources in the geothermal system. “Geothermal energy” means the usable energy that is produced or that can be produced from a geothermal resource. “Geothermal resource” means the natural heat of the earth and the energy, in whatever form, that is present in, associated with, or created by, or that may be extracted from, such natural heat, as determined by the regulations of the Department. “Geothermal system” means any aquifer, pool, reservoir, or other geologic formation containing geothermal resources.