Constructed in 1891, this dam created a body of water known variously as the City Reservoir, Ennis Railroad Lake, and Old City Lake. It was built in answer to a proposal by the Houston and Texas Central Railroad to move its divisional headquarters to Ennis from Corsicana. The lake provided water for the train station and machine shops. The location of the railroad here contributed to the growth of the city, and in recent years the Old Lake Dam has provided recreational facilities and flood control for the area.