Abstract: An automatic feedback controller for maintaining water level in a dam initially compares target and sensed water levels to derive a deviation value. Simultaneously, a first dead zone having a relatively wide width contiguous to the target level is set. The first set dead zone is compared with the deviation value to open and close a dam gate such that the deviation value becomes smaller than the first dead zone width. When a predetermined time has elapsed, a second dead zone having a width narrower than that of the first dead zone is set. The second dead zone is then compared with the deviation value to open or close the gate such that the deviation value becomes smaller than the second dead zone width.