The river usually stands at 14 feet above sea level, while Lake P usually stands at 1 foot above sea level. To move a ship from one to the other you need a lock, a box with doors on both ends. Ship sails in, doors close, water is pumped in or out to match levels with the far side, the door opens, and the ship sails out. One of the locks between the river and Lake P is broken, per anecdotal live news reports and per the NO Times Picayune, with the doors in the open position. Trying to find out which one.
Check the Industrial Canal. It has (at least one) set of locks, and that canal communicates between the lake and the river.
The Bonnet Carre Spillway is opened by lifting creosoted timbers out of place. It isn't made up of "doors" the way a lock is. I doubt the Bonnet Carre' Spillway is open at all.
if you know - where in the city are the locks located?