The "Batch Plant" is a 100' diameter concrete wall tank that was used for cleaning the aggregate used during the the construction of Hoover Dam.  The wall is approximately 15' high with a concrete column located at the center of the tank. This column served as a pivot point for a structure that rotated around the interior perimeter of the tank.  

A smaller rectangular tank is located due south approximately 80' away from the main tank. The top rim of the main tank  is at 1135' above sea level with the lowest point at 1118' above sea level. Because the lake elevation fluctuates, you can calculate the current depths (normally between 60'-90') by subtracting their elevation from the current lake elevation. For current lake levels, visit the US Bureau of Reclamation website.

The tank is located off the western tip of the the northern-most Boulder Island (GPS coordinates N 36^O 02.425'   W114^O 46.292').  An arrow indicates the approximate location of the submerged tank.

The following photo (slightly blurred) is a panoramic view of the Boulder Islands.  Besides the Batch Plant, there is also the "Tortuga" (cabin cruiser) and "Cold Duck" (smaller boat,) located between the two larger islands.  The locations noted are approximate (assuming the boats have not been relocated.)  I hope to provide photos and more accurate positions and depths for each in the near future.