During World War II, the dam was the target of a German bomb plot.

During World War II, the dam was the target of a German bomb plot.

In November 1939, with World War II underway, U.S. officials found out about an alleged plot by German agents to bomb Hoover Dam, by planting bombs at the intake towers to sabotage the power supply to Southern California’s aviation manufacturing industry. After American authorities learned of the plot, private boats were prohibited in the Black Canyon, stricter regulations for dam employees and visitors were enacted and a variety of other security measures such as physical barriers and increased lighting were put in place. Following the attack on Pearl Harbor in December 1941, the dam was closed to visitors for the rest of the war. The dam had its own police force but the Army provided some personnel to help guard the dam. Additionally, government officials investigated various possibilities for protecting the dam from an aerial attack, such as large-scale smoke screens or the construction of a decoy dam, but none of these options were used. Hoover Dam reopened to the general public in September 1945.