(a) The authority may control, develop, store, and use the natural flow and floodwaters of the San Antonio River and its tributaries for the purpose of operating and maintaining:
(1) navigable canals or waterways; and
(2) navigational systems or facilities auxiliary to navigable canals or waterways.
(b) The navigational use of water authorized by Subsection (a) is subordinate and incidental to consumptive use of water.