An automatic trip gate for installation in a gate support structure at a bank of an impounded body of water. The automatic trip gate controls a release of an overflow of water through the gate support structure upon the occurrence of an overflow event. The automatic trip gate includes a plate supported by a hinge assembly that attaches to the support structure. A trough attached to the plate catches and retains overflow water. When the level of overflow water in the trough reaches a tipping level, the plate pivots from a substantially vertical orientation wherein the impounded body of water is maintained behind the plate, to a tipped position wherein the impounded body of water is released o through the gate support. A plunge pool is located below the automatic trip gate that absorbs the energy imparted by the plate when tripped.