Hard to say, because we can't see if the southern gates on the lock are open, though the northern gates are. Checking google maps ( http://maps.google.com/maps ), that picture is looking NNE, and so it is draining into the Arabi section, not the central city section. That Arabi bowl(eastern NO) is the one that flooded earliest yesterday, and where yesterday's rooftop flooding and rescue shots were coming from. Also speculated that 22' storm surge from the hurricane overtopped and began filling it from the east. Am wondering if there is now an east breach, and as much of the river that fits through the lock is draining through that bowl to the sea.
Yes, my guess is that what you call is Arubi section is dumping its above sea level water load through the breach in the levee down to the sea level navigation channel. It seems from the pic, that the water is up to the top of the levees in Arubi.