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. The Old Lake Dam, now called Chambers Creek Watershed, Site 20a, was reconstructed in 1988 by the U.S.D.A., Soil Conservation Service, in cooperation with the Ellis - Prairie Soil and Water Conservation District and the City of Ennis, to provide flood control and continued recreational benefits.