LOST VEGAS: The Secret Nazi Plot to Blow Up Hoover Dam

Posted on: March 3, 2025, 01:30h. 

Last updated on: March 3, 2025, 12:24h.

Corey Levitan Read More
Expertise: Commercial Gaming, Entertainment, Expert Insight, Las Vegas, Restaurants, Las Vegas Myths.
  • Nazi spies once plotted to blow up Hoover Dam, a catastrophe that would have altered the course of WWII
  • Their purpose was to cut off electricity to Southern California’s airplane factories
  • Intel from the US Embassy in Mexico and swift action from the federal government intervened

In November 1939, the US was warned about a Nazi plot to bomb Hoover Dam. Such a catastrophe would certainly have hastened our country’s entry into the war by two years.

These four intake towers feed Lake Mead water into the Hoover Dam’s 17 turbines. In 1939, back when the lake was 78%-80% full instead of just 32%, a boat could have approached any one of them high enough to insert explosive devices inside. (Image: usgs.gov)

The warning came from the US embassy in Mexico, which had learned that two German spies living in Las Vegas planned to rent a boat under the guise of a Lake Mead fishing trip. One of them, a munitions expert, would plant bombs inside one or more of the dam’s four intake towers.

This explained the mysterious German man a ranger had already reported taking a copious number of photos around the dam on more than 12 occasions in the previous month.

Hoover Dam as photographed in 1941. (Image: Ansel Adams via Wikipedia)

USBR responded by immediately banning private boats on Lake Mead, installing floodlights to illuminate the intake towers, and increasing the number of rangers patrolling the dam on foot. It even hung a steel mesh across the lake, right above the dam, preventing any boats from getting without 300 feet of the intake towers.

The new restrictions led to speculation among employees, public, and of course, the media. On December 7, 1939, A. E. Cahlan, a columnist for the Las Vegas Evening Review, described the plot to sabotage the dam in fairly accurate detail.

Because of the plot’s classified nature, however, USBR Commissioner John Page issued a press release in January 1940 stating that “there has been no ‘plot’ unearthed” and that “reports that the Bureau of Reclamation is fearful that someone will dynamite the dam are ridiculous.”

Continuing his lie in the name of national security, Page continued: “There is quite a suction near the intake towers and only experienced pilots, such as those of the regular sight-seeing boats and of the government boats, are permitted near this water.”

Pooping Their Dam Pants

Behind the scenes, the Bureau was terrified. Page was highly aware of the damage that crippling the Hoover Dam would inflict on the US war effort.

Shutting down the electricity produced by the dam would render the airplane factories of Lockheed, Douglas Aircraft and the rest of Southern California’s burgeoning aviation industry powerless for perhaps months.

Even after the precautions were enacted, strange activity persisted in the area. Shots were fired at a National Park Service patrol boat, and an unauthorized car was spotted driving away from a no-trespassing zone. A USBR warehouse at Parker Dam, 150 miles downstream from Hoover, was burned down in July 1940. (In the ruins, fragments of an explosive device were discovered — just like the one that exploded that same month at the World’s Fair grounds in New York, killing two cops.)

This 24-foot by 14-foot military bunker, with 13”-thick walls, was constructed high on a cliff on the Arizona side of Hoover Dam following the Pearl Harbor attack. Featuring six gun ports, the abandoned “pill box” still sits there today, silently guarding the dam against attackers who never arrived.

The panicked Bureau hired the services of a “color consultant,” who recommended painting the dam “bold, simple masses of colors” to camouflage it from planes overhead. Another proposal included building a decoy dam downstream.

The German effort was obviously thwarted without the approval of either of these proposals. And the German agents — whose names were never publicly revealed — most likely fled. (Details of their arrest are absent from public records.)

One day after the US entered WWII following the Dec. 7, 1941 Japanese bombing of Pearl Harbor, USBR closed Hoover Dam to all visitors except “those on official business.” A few weeks later, a secret military bunker was constructed on the dam’s Arizona side.

Hoover Dam didn’t completely reopen to the public until the war ended in 1945.

The Accidental Way We Found Out

We only know any of this thanks to Christine Pfaff. A USBR historian, Praff happened to be researching facts as part of what she figured would be a humdrum historical review marking her agency’s 100th anniversary in 2002.

Instead, in the National Archives, she stumbled across recently declassified documents in a series of plain brown files marked “confidential.” Pfaff detailed her discovery in this 2003 article for Prologue Magazine, a quarterly publication produced by the National Archives and Records Administration.

Yet the averted national tragedy remains a widely unknown part of Las Vegas history.

“Lost Vegas” is an occasional Casino.org series spotlighting Las Vegas’ forgotten history. Click here to read other entries in the series. Think you know a good Vegas story lost to history? Email corey@casino.org.