Flaming Gorge was built in block-shaped stages of concrete called "forms". The first concrete for the powerhouse was placed on September 8, and construction of the main dam wall began ten days later. In order to accelerate hardening of the concrete, cold water was pumped through metal tubing, or "coils", embedded in the structure. Concrete placement continued until November 15, 1962, when workers topped out the dam. By the end of 1962, both the river outlet works and the spillway tunnel were completed, and the diversion tunnel was closed, allowing water to begin rising behind the dam. The dam's hydroelectric generators were installed by mid–August 1963 and the first unit went into operation on September 27 at the press of a switch by President John F. Kennedy. The dam was officially dedicated by Lady Bird Johnson on August 17 of the following year.