Here is view of the original Emergency Dam being tested at the Gatun Locks.  In case an accident occurred to the locks gates, allowing a free passage of water from the 85-foot lake level, to the sea level. the dam would be swung across the lock chamber (as shown) and a series of wicket girders hinged to it would be lowered with their ends resting in pockets in the lock floor.  Steel gates would then be lowered down, one at a time, which would close the lock chamber and check the flow of water.  There were two emergency dams at each of the three locks on the lake end or fresh water end.
   In the Isthmian Canal Commission Annual Report for 1916, it talks of having monthly drills to keep the Emergency Dam crew familiar with different scenarios.  They would test both at day and night.  If per chance there was an emergency, and due to the loud noise caused by the rushing water, the whole operation was done in silence and with hand signals.  It states that "arrow signals were installed near the gates on each girder so that the silver operators can signal when the hooks are clear or in place on the gates."
    The photo below shows the wicket girders in place and the steel gates lowered.    

    In the late 1930's, the Special Improvement Project 7 (SIP 7) Emergency Dams replaced the original dams.  The SIP 7 dam was raised out of slot in the bottom of the Lock chamber hydraulically or with compressed air.  The SIP 7 Emergency Dams were retired in the late 1980's.  Today, there is no emergency dams in use at the Panama Canal Locks.  

Another part of our Canal Zone heritage now captured and preserved on the World Wide Web!!  Long live the glory and memory of our Zonian history!