(a) If approved by a two-thirds vote of the qualified voters of the district voting at an election held for that purpose, the Commissioners Court of Galveston County may impose an annual ad valorem tax at a rate not to exceed 20 cents on each $100 valuation of taxable property in the district for the maintenance of the district’s improvements and facilities.
(b) An election under Subsection (a):
(1) does not require a petition;
(2) must be held in the same manner prescribed for a bond election; and
(3) may be held at the same time as a bond election.

(c) Subsequent elections may be held on increasing, reducing, or abating a maintenance tax not to exceed the limits prescribed by Subsection (a).