It shall be the duty of the district engineer:

1. (1) to make all necessary surveys, examinations, investigations, maps, plans, and drawings with reference to proposed improvements;
2. (2) to make estimates of the cost of proposed improvements;
3. (3) to supervise the work of improvement; and
4. (4) to perform all duties which may be required of him by the commission.

Acts 1971, 62nd Leg., p. 110, ch. 58, Sec. 1, eff. Aug. 30, 1971.