California Code, Public Utilities Code - PUC § 103357

(a) The district may issue bonds payable from the proceeds of the retail transactions and use tax.

(b) The maximum bonded indebtedness which may be outstanding at any one time shall be an amount equal to the sum of the principal of, and interest on, the bonds, but not to exceed the estimated proceeds of the transactions and use tax, as determined by the district.  The amount of bonds outstanding at any one time does not include the amount of any bonds or refunding bonds for which moneys or securities necessary to provide for the payment thereof have been set aside for that purpose in a trust or escrow account.