National Archive documents are proof that Hoover Dam was considered a strategic and vulnerable target for sabotage. During World War II, with Hitler’s aggression growing worse, our government became sensitive to these enemy threats on the dam. 

A careful eye was kept on dam employees, and stricter regulations were enforced for visitors at Hoover Dam. But as tensions mounted and the War Department uncovered evidence of several bomb plots, security became even more critical. 

Documents show a plot by German agents to bomb Hoover Dam by planting explosives at the intake towers. The intent was to cut off power to our nation’s biggest defense plants in Southern California, where warplanes and tanks were manufactured. German agents living in Las Vegas (one of them an explosives expert) had made several trips to the dam as they formulated their plan to sabotage it. FBI members were deployed to the dam site to assess how best to protect it.

The State Department told officials at Hoover Dam to keep the plot highly confidential so that the public (and press) wouldn’t find out. Authorities banned private boats from the Colorado River in the area of Black Canyon. And the National Park Service increased their patrols around Lake Mead.

Even as rumours by the media of a conspiracy to bomb the dam were  denied by officials, intelligence was being uncovered that Berlin was issuing life or death orders to bomb Hoover Dam. Security forces were increased at the dam, armed guards were brought in, and additional gates, doors and other barriers were installed.

After the attack on Pearl Harbor (Dec.1941) the dam was closed to tourists for the remainder of the war. And it wasn’t until 1945 that Hoover Dam reopened to the public.

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