Tex. Water Code § 49.153

(a) The board, without the necessity of an election, may borrow money on negotiable or nonnegotiable notes of the district to be paid solely from the revenues derived from the ownership of all or any designated part of the district's works, plants, improvements, facilities, or equipment after deduction of the reasonable cost of maintaining and operating the facilities.

(b) The notes may be first or subordinate lien notes within the discretion of the board, but no obligation may ever be a charge on the property of the district or on taxes levied or collected by the district but shall be solely a charge on the revenues pledged for the payment of the obligation. No part of the obligation may ever be paid from taxes levied or collected by the district.

(c) Except as provided by Subsection (e), a district may not execute a note for a term longer than three years unless the commission issues an order approving the note.

(d) This section does not apply to special water authorities.

(e) Subsection (c) does not apply to:

(1) a note issued to and approved by:

(A) the Farmers Home Administration;

(B) the United States Department of Agriculture;

(C) the Texas Water Development Board;

(D) the North American Development Bank; or

(E) a federally chartered instrumentality of the United States authorized under 12 U.S.C. Section 2128(f) to provide financing for water and waste disposal facilities, provided that the district that executes the note is located wholly in a county that:

(i) does not contain a municipality that has a population of more than 750,000; and

(ii) is not adjacent to a county described by Subparagraph (i); or

(2) a district described by Section 49.181(h).