(a) To provide money for any purpose provided by this chapter or another law relating to navigation districts, the board may issue bonds secured:
(1) solely by a pledge of and payable from the net revenue derived from the operation of all or a designated part of the district’s improvements and facilities then in existence or to be constructed or acquired;
(2) by a pledge of and payable from an ad valorem tax on all taxable property in the district under Section 59, Article XVI, Texas Constitution; or
(3) by a combination of the methods prescribed under Subdivisions (1) and (2).
(b) If bonds issued under Subsection (a)(1) are outstanding, the board shall charge and collect fees, tolls, and charges sufficient to:
(1) pay all maintenance and operation expenses of the improvements and facilities, the income of which is pledged;
(2) pay the interest on the bonds as it accrues;
(3) pay the principal of the bonds as it matures; and
(4) make any other payments prescribed in the bond order or resolution.

(c) If bonds issued under Subsection (a)(2) are outstanding, the board shall annually impose a tax sufficient to pay:
(1) the interest on the bonds as it accrues; and
(2) the principal of the bonds as it matures.
(d) If bonds issued under Subsection (a)(3) are outstanding, the board shall charge and collect fees, tolls, and charges so that, in the manner prescribed in the bond order or resolution, the amount of tax to be collected may be reduced or abated to the extent that the revenue from the operation of the improvements and facilities, the income of which is pledged, is sufficient to:
(1) meet the requirements for maintenance and operation of the improvements and facilities; and
(2) provide money for the bonds as prescribed in the bond order or resolution.
(e) All district bonds must be authorized by board resolution or order.
(f) Bonds payable solely from net revenue may be issued without an election.