p.23 #1725 Close-up of upper portal of Diversion Tunnels No. 3 & 4, during preparations for blast. Nov. 13, 1932. p.23 #1728 Close-up of upper portals of Diversion Tunnels No. 3 and 4, showing flow in diversion tunnel No.4, shortly after blast. Nov. 13, 1932. p.23 #1733 Dumping materials at temporary pile bridge to complete diversion of Colorado River. Nov. 13, 1932. p.23 #1737 Upper portals of Diversion Tunnels No. 3 & 4, and temporary dyke, after diversion of Colorado River was completed. Nov. 26, 1932.