p.24 #1766 - p.24 #1767 Panoramic view of upper cofferdam, looking downstream. Nov. 26, 1932. p.24 #1744 Lower portals of Diversion Tunnels No.3 & 4, after diversion of Colorado river was completed. Nov. 14, 1932. p.24 #1778 Upper cofferdam, taken from Lookout Point. Nov. 29, 1932.