(a) If the proceeds of bonds issued by a district are insufficient to complete the proposed improvement or construction, if the commissioners decide to begin other and further construction or improvements, or if additional funds are required to maintain the improvements made, the commission shall certify to the commissioners court the necessity for an additional bond issue.
(b) Unless the amount previously authorized has been exhausted, the commissioners court shall issue the bonds.

(c) The certification to the court shall state:
(1) the amount of bonds required;
(2) the purpose of the bonds;
(3) the rate of interest; and
(4) the length of time for which the bonds are to run.