Hoover Dam Explosion Cause Determined to Be Blown Transformer

The cause of an explosion that rocked the Hoover Dam on Tuesday and resulted in a fire has been determined.

The incident was first witnessed by tourists at the famed Nevada dam on Tuesday morning, with the Boulder City Fire Department being called to the location at around 10:30 a.m. local time. Videos taken by witnesses circulated across social media in the immediate aftermath of the explosion and showed black smoke billowing up from the iconic structure.

The blaze was ultimately brought under control quickly by the dam's own fire personnel and was fully extinguished by the time the local fire department arrived, KLAS-TV reported. The cause of the incident was determined to be a faulty transformer that exploded.

"At approximately 10 a.m. PDT the A5 transformer at Hoover Dam caught fire within the last hour and was extinguished by the Reclamation/Hoover fire brigade at approximately 10:30 a.m. PDT," Jacklynn L. Gould, regional director for the Bureau of Reclamation, said in an official statement provided to Newsweek. "There are no injuries to visitors or employees. There is no risk to the power grid, and power is still being generated from the powerhouse. We are investigating the cause of the fire and will provide additional updates as they are available."

hoover dam explosion fire transformer
A blown transformer was determined to be the cause of an explosion that led to a fire at the Hoover Dam on Tuesday morning. Above, the famous dam is pictured in 2009. Ethan Miller/Getty Images

The videos of the incident circulating online are shot from high atop the dam or surrounding structures, looking down at the smoke and fire, which can be seen originating from a specific spot near the base along the Colorado River.

An official tweet from the Bureau of Reclamation included two photos in which fire personnel could be seen fighting the blaze.

The explosion had little impact on the dam's daily operations. Tours of the structure were paused for only 30 minutes while the fire was brought under control. No other details about the incident are available at this time.

Built over five years during the Great Depression and named after President Herbert Hoover, the Hoover Dam spans the Colorado River's Black Canyon at the border between Nevada and Arizona. Located roughly 30 miles southeast of Las Vegas, the dam is a major source of hydroelectric power for the region, providing electricity for public and private utilities in Nevada, Arizona, and California.

The dam is also a major tourist destination for the area. According to data published by the National Parks Service in 2018, around 7 million people visit the Hoover Dam each year, with tours offered by the Bureau of Reclamation.

Update 7/19/2022 at 5:00 p.m. ET: This article has been updated to include a statement from the Bureau of Reclamation.