On January 23, 1925, Philadelphia Electric Company awarded the construction contract for the dam to Stone & Webster of Boston, who did the design. Construction, which started in 1926, was carried out by Arundel Corporation of Maryland. (Abandoned railroad tracks for transporting heavy equipment to the dam site can be seen along the western shore of the river below the dam.) When completed in 1928, it was the second-largest hydroelectric project by power output in the United States after Niagara Falls.