The bowls are not lower than the gulf in parts of the city. Some parts of the city I have seen under water are a couple of feet above sea level. If there is water on Bourbon Street, which is six feet above sea level, it is seven feet above sea level.
You're not taking in to account outflow from the headwaters that were surged. If the outlet for the lake to the Gulf is constricted then the bowls get the water. Sea level is relative at this point.