Cal. Public Utilities Code § 16475

(a) A public utility district which acquires, constructs, owns, operates, controls or uses works for supplying its inhabitants with water, may, pursuant to the notice, protest, and hearing procedures in Section 53753 of the Government Code, fix and collect a water standby or immediate availability charge on all land within its boundaries to which water is made available for any purpose by the district, whether the water is actually used or not, except that such charge shall not supply to lands permanently dedicated exclusively to transportation of persons or property. If the procedures set forth in this section as it read at the time a standby charge was established were followed, the district’s board of directors may, by resolution, continue the charge pursuant to this section in successive years at the same rate. If new, increased, or extended assessments are proposed, the district shall comply with the notice, protest, and hearing procedures in Section 53753 of the Government Code. (b) The board of directors of the district which fixes such a charge may establish schedules varying the charges in different months and in different localities within a public utility district depending upon factors such as the uses to which the land is put, the cost of transporting the water to the land, the degree of availability or quantity of use of such water to the affected lands. The board may not, however, fix an annual charge in excess of ten dollars ($10) per acre or in excess of five dollars ($5) for parcel of less than one acre, unless the standby charge is imposed pursuant to the Uniform Standby Charge Procedures Act (Chapter 12.4 (commencing with Section 54984) of Part 1 of Division 2 of Title 5 of the Government Code). (c) If a person for more than one year obtains substantially all of his or her water requirements for the contiguous parcels of land which he or she occupies from rainfall, springs, streams, lakes, rivers, or wells, and if the person’s primary economic activity on such land is the commercial extraction or processing of minerals, such land shall be exempt from any water standby or availability charges. (d) Any funds derived from the charges levied pursuant to this section may be used by the district for all purposes which a public utility district is authorized to expend funds insofar as said purposes relate to the acquisition, construction, operation, control, or use of works for supplying its inhabitants with water.