 It was located at a narrow point between the Lower and Upper Mystic Lakes, with its west end in Arlington and its east end in Medford.The water system it was a part of eventually merged into the Metropolitan District Commission (MDC), predecessor to the Massachusetts Water Resources Authority (MWRA) and the Massachusetts Department of Conservation and Recreation (DCR).As built, the dam was over long and high, with most of that length (about ) consisting of earthen embankments lined with riprap and puddle clay.