(a) At the time general obligation bonds are issued under § 1070.252, the board shall impose an ad valorem tax at a rate sufficient to create an interest and sinking fund to pay the principal of and interest on the bonds as the bonds mature.
(b) The tax required by this section together with any other ad valorem tax the district imposes may not in any year exceed the tax rate approved by the voters at the election authorizing the imposition of the tax.