Consists of two tunnels of portal section of 14x14m, located over the left margin of the river,  excavated on rock covered with hydraulic concrete on sole and walls and thrown concrete on the vault, design to travel over the design flow (5 730.60 m3/s). the entrance and exit portals will be excavated on rock, each tunnel has a Tailrace covered with concrete to host and operate the Stoppers activated by steady lathes in order to control de flow of the water. The door will slide through a vertical Tailrace covered with concrete trough a lathe, the installed mechanism will be on the platform besides the mark that will support the door during the final closure. 

It will be complemented with two cases built with graduated material, the impermeable nucleus of both will be linked to an impermeable screen built over an alluvium, all over the healthy rock on the bottom of the river bed, to avoid filtrations to the Dam construction zone, guaranteed the correct construction of the impermeable nucleus and screen to achieve the proper conditions for the placement settling. This consists on keeping the zone dry, it is convenient to perform the constructions of the cases before the raining period.

Construction of two diversion tunnels of 14m x 14m each one; length T1 = 693.35 m, length T2 = 750.57 m