(a) Not later than January 1 of each year, the board shall conduct a review to determine what percentage of the developable acreage in the district has been developed. The board by rule shall establish criteria for determining whether certain acreage is developable.(b) If the board determines on conclusion of a review conducted under Subsection (a) that at least 90 percent of the developable acreage in the district has been developed, Section 3861.052 does not apply to the district and all five directors shall be selected by elections held on the uniform election date in May in even-numbered years.(c) If the board makes the determination described by Subsection (b), a director appointed to the board before the board makes that determination is entitled to serve the remainder of the director's unexpired term.(d) A vacancy on the board that occurs on or after the date the board makes the determination described by Subsection (b) shall be filled in the manner prescribed by Section 3861.054(b). Added by Acts 2015, 84th Leg., R.S., Ch. 439 (H.B. 648), Sec. 3, eff. September 1, 2015.