Tex. Const. art. 3, § 49-d-3

CREATION AND USE OF SPECIAL FUNDS FOR WATER PROJECTS. (a) The legislature by law may create one or more special funds in the state treasury for use for or in aid of water conservation, water development, water quality enhancement, flood control, drainage, subsidence control, recharge, chloride control, agricultural soil and water conservation, desalinization or any combination of those purposes, may make money in a special fund available to cities, counties, special governmental districts and authorities, and other political subdivisions of the state for use for the purposes for which the fund was created by grants, loans, or any other means, and may appropriate money to any of the special funds to carry out the purposes of this section. (b) Money deposited in a special fund created under this section may not be used to finance or aid any project that contemplates or results in the removal from the basin of origin of any surface water necessary to supply the reasonably foreseeable water requirements for the next ensuing 50-year period within the river basin of origin, except on a temporary, interim basis. (Added Nov. 5, 1985.)