What matters now is the elevation of the city, about which I have now become an expert. The areas near the river are all abo above sea level typically from 5-10 feet above sea level. There is no surge now. Some posit the lake is rising like a top. Is that creditable. Here is a pic. The one water way is about 2 miles wide and there is another, and the "land" area is swamp, and if it is more than a couple of feet high I would be amazed. The idea that the lake can rise much in calm weather strikes me as not creditable.
I guess you're going to make me find that damn graphic.
While lake level may be sea level the river is higher than sea level. And if the industrial canal is breached which connects the river to the lake than it's possible that the river is now flowing in to St. Bernard and the lake at the same time.