After consulting with a New York engineering firm, Butler reported to Carnegie that a lake could be constructed for $118,000 (about $2.5 million in today's dollars). It was one of the great underestimations in Princeton's history: the final cost would be about $450,000 (about $9.5 million today). Working through a local agent, Carnegie began acquiring property in 1903, and by 1905 all necessary acreage was secured and crews set to work clearing the land and constructing bridges and the dam. The lake's official opening occurred on December 5, 1906.
Initially, Lake Carnegie was owned by a nonprofit organization, but in 1934 it was deeded to Princeton University. However, the lake's construction was not yet complete. Its shallowness led to silting and subsequent flooding, and the University would dredge the lake three times in its first 65 years: in 1927, in the late 1930s and in 1971. The last excavation gave the lake a uniform depth of nine feet at a 35-foot distance from the shoreline. In addition, the Washington Road Bridge would be widened, the Harrison Street Bridge replaced and the dam reinforced. But in the midst of all these efforts, the crew team always had its lake.