Just got answer. This is part of BC spillway. Locks on the Miss can be opened for water to exit the River above NO and go thru a big swath of the land, spillway, and go into Lake Ponchatrain.
I wonder if this means that water from the Lake going over those levees is Miss River water.
I haven't heard this before so it is in the area of rumor, maybe false. People outside NO should be able to see and report it if so.
If what you says is true, that will put Lake P none feet above normal. Storm surge is forecast at 6 to 8 feet, so this will make it worse. I think they will sum greater than either contributing factor, because water is slow draining from Lake P.
Hate to say it but I think downtown is going to flood again.