Cal. Pub. Util. Code § 16575

A district may issue bonds for the purpose of acquiring or constructing any waterworks necessary or proper for carrying out the objects and purposes of the district, in like manner as other bonds are authorized to be issued under this division, and may pledge the revenue, income, receipts, and profits from the operation of the waterworks to the payment of the principal of and interest on the bonds. A district may, if it so elects, declare the payment thereof shall be made solely from the revenue, income, receipts, and profits.