The Rocky Flats Plant was a former nuclear weapons production facility in the western United States, near Denver, Colorado. Operated from 1952 to 1992, it was under the control of the U.S. Atomic Energy Commission (AEC), succeeded by the Department of Energy (DOE) in 1977. Weapons production was temporarily halted in 1989 after EPA and FBI agents raided the facility. Operators of the plant later pleaded guilty to criminal violations of environmental law.