California Code, Public Utilities Code - PUC § 180250

(a) As part of the ballot proposition to approve the imposition of a retail transactions and use tax, authorization may be sought to issue bonds to finance capital outlay expenditures as may be provided for in the adopted county transportation expenditure plan, payable from the proceeds of the 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 tax, as determined by the plan. The amount of bonds outstanding at any one time does not include the amount of bonds, refunding bonds, or bond anticipation notes for which funds necessary for the payment thereof have been set aside for that purpose in a trust or escrow account.