(a) At any time, the board may on its own motion call a hearing on the question of the exclusion of land from the district as provided by Chapter 49, Water Code, if the exclusion is practicable, just, or desirable.
(b) The board shall call a hearing on the exclusion of land or other property from the district if, before the issuance of bonds has been authorized, a property owner in the district files a written petition with the secretary of the board.