Aggregate Plant

Aggregate Plant at Lake Mead

The Underwater Treasures of the Wild West

In 1932, Thomas M. Price and representatives from the Six Companies, Inc. joined forces to create the Aggregate Classification Plant. The Six Companies were actually six construction and engineering companies who had to pool their talents and resources in order to bid on the construction contract and build the Hoover Dam. The Plant remains a symbol of ingenuity needed to assist in creating western American history. Upon completion of Hoover Dam, it was abandoned in Boulder Basin and currently rests about 115 feet below Lake Mead’s surface. The former Aggregate Classification Plant is now a boat-friendly freshwater dive site spreading across eight underwater acres. Its mechanical remains are a must-see spot for inquisitive divers looking to explore.

Aggregate Plant Site Plan

Site plan of the aggregate plant at lake mead

About the Aggregate Plant

The Aggregate Classification Plant was originally created to wash and sort through aggregate matter that was to be used in concrete mixings for the construction of Hoover Dam.

Due to the successful speed of the mixing plant and producing over nine million tons of aggregate, the plant was able to provide a constant flow of mix into the needed concrete and led to completing the Hoover Dam two years ahead of schedule.

At the end of the Plant’s role in the amazing effort to build Hoover Dam, much of the leftover steel and equipment was sold to projects to build future dams out west. Abandoned, the skeletal remains of the Aggregate Plant were covered by Colorado River water as Lake Mead filled beginning in the summer of 1936.
  • In late October of 1931 to 1932, construction began on the Aggregate Classification Plant.
  • On January 7th, 1932, the plant tested their systems for the first time.
  • The mixing plant processed their first sample of aggregate on January 9th, 1932.
  • On January 9th, 1932, the Aggregate Plant had their first trial run.
  • The plant began official production on February 6th, 1932.
  • The Aggregate Classification Plant shut down on November 29th, 1934.
  • Most of the steel structures and materials were removed during 1935.
  • The plant was submerged in water by the summer of 1936.
  • Between the years of 2017 and 2020, the National Park Service continuously worked to document the historic remnants of the Aggregate Classification Plant – allowing the park to protect and preserve this legendary site.
  • It is currently a fresh-water diving site for experienced divers to explore.
What You’ll See:
  • Steel-framed structures
  • Conveyor belts
  • Concrete tunnels
  • Railroad tracks
  • Four giant piles of aggregate
Depth: About 115 feet below the water’s surface.
Location: Boulder Basin at Lake Mead.

Experience other diving destinations at Lake Mead as you continue to discover the underwater treasures of the wild west.

Last updated: April 22, 2021

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