Cal. PUC § 33002

(a) In determining the amount of a special benefit assessment, the board may measure the benefit to real property in the benefit district or zones therein by the parcel area of unimproved real property and by the parcel area and the floor area of real property and improvements thereto of improved real property, as deemed appropriate by a resolution adopted by a two-thirds vote of the members of the board.

(b) The special benefit assessment constitutes a charge imposed on particular real property for a district project of direct benefit to that property, and does not constitute ad valorem taxes or any other form of general tax levy applying a given rate to the assessed valuation of all taxable property within the district.

(c) The district shall possess all powers necessary for, incidental to, or convenient for the collection, enforcement, administration, or distribution of the special benefit assessment in accordance with California law.

(d) The revenue from a special benefit assessment, which is imposed pursuant to this chapter, or from bonds secured by such a special benefit assessment, for the purpose of financing a rail transit station or rail transit related facility located within the benefit district, shall be used only for financing of the facility for which it was levied, and that revenue shall not be used for any other purpose or the payment of any other expense of the district, including, but not limited to, transit, transportation, or operating expense.