Captions: On the left, the gate structure to #4 diversion tunnel, 165 ft high. On the right side the upper portal to #3. Note: bulkhead in foreground, will be blown out after the completion of coffer dam, allowing water to pass thru; Coffer dam - Boulder Dam '32; Looking down a completed tunnel. Just before the water was diverted. Sunday Nov. 13, 1932, Hoover Dam.
Black and white image showing an upstream view of Black Canyon from the Hoover Dam construction site. In the distance, Fortification Hill can be seen along with tunnel lining forms near the inlet portals of the Nevada diversion tunnels. Note: Boulder Dam was officially renamed Hoover Dam in 1947.