(a) Unless the board by resolution increases the rate of reimbursement to an amount authorized by Section 49.060, Water Code, a director other than a director described by Subsection (c) is entitled to receive $50 a day and reimbursement for actual and necessary expenses incurred for each day the director:
(1) attends a board meeting; and
(2) attends to the business of the district that is authorized by board resolution or motion.
(b) A director is not entitled to receive a per diem allowance for more than 60 days in a calendar year.

(c) If a member of a commissioners court or a municipal government officer is appointed as a director, the member’s or officer’s service as a director is considered an additional duty of the member’s or officer’s existing office. The member or officer is not entitled to a per diem allowance under this section, but is entitled to reimbursement for actual and necessary expenses incurred in performing official duties as a director.