For all who questioned: there is a boat in the lock, that is why the water is being let out. The waiting is for the boat that is just about to appear at the new, lower, level.
There probably is a lot of waiting to do at a lock, but the wind on the flags, and the water escaping from the gate dosn't make me thing waiting. It would have been great if you could have got a shot of a boat in the lock...