In the prosecution of the plans for which the authority has been created for the storing, controlling, conserving, and distributing for useful purposes of the storm waters, floodwaters, and unappropriated flow waters of the Brazos River watershed and developed groundwater from the Brazos River basin for the use of its customers, the authority may use the bed and banks of the Brazos River and its tributary streams for any and all purposes necessary to the accomplishment of the plans of the authority.