The dam held back water flowing into the reservoir and was built mostly from materials found on site, likely with a trench dug into bedrock to strengthen the foundation and prevent leakage, a clay core that may also have included concrete made with sand cleared from the basin, and larger stones placed on the inner face to resist wave erosion. Construction was aided by a dinky locomotive engine and dumper cars running on a small track to haul dirt and other materials to the crews along the dam. The concrete outlet tower, about 21 feet tall, worked with a system of pipes to transfer reservoir water to Morgantown. Three levels of side intake openings were controlled by hand from the top of the tower, which the reservoir caretaker reached by walkway to open or close the intake gates according to water levels and need. When the lake stood at normal depth, only the top of the tower remained visible above the water. Water collected in the bottom of the tower and entered a concrete-sealed 24-inch-diameter main outlet pipe that passed under the dam's core and connected to pipes leading to town. On November 27, 1912, water from Tibbs Run was turned into the reservoir, the gatehouse valves were closed, the reservoir began to fill, and the improvement was said to have cost about $50,000.