(a) After bonds other than preliminary bonds are voted, the board may authorize the issuance of the bonds in whole or in part as they are needed by the district.
(b) The board shall levy and annually assess and collect sufficient taxes to pay principal and interest on the bonds.

(c) The bonds may be approved by the attorney general and registered by the comptroller before the filing of the report of the commission under Section 51.421 of this code.