Abstract: A self-regulating tide gate system for a headwall placed over a channel, stream or river exposed to tides or floods with at least one gate opening formed therein. Disposed on the downstream side of the headwall on opposite sides of the gate opening is at least one pivotally attached door panel designed to swing downstream to allow flow in the downstream direction. When water levels are such that flow in the upstream direction is possible, the door panel is held open thereby allowing some backflow. When the backflow generates a sufficient force, the door panel closes. Attached to each door panel is a guide line. Attached to the guide lines is at least one elastic cord or strap designed to apply a variable tension force to the guide lines to hold the door panels in an open position and progressively resist closure of the door panels when the draft force generated by the upstream flow of water matches or exceeds the tension in the guide lines.