(a) The commissioners court may prescribe:
(1) the method of making purchases and expenditures by and for the district; and
(2) accounting and control procedures for the district.
(b) The commissioners court by resolution or order may delegate its powers under Subsection (a) to the board.
(c) A county officer, employee, or agent shall perform any function or service required by the commissioners court under this section.
(d) The district shall pay salaries and expenses necessarily incurred by the county or by a county officer or agent in performing a duty prescribed or required under this section.