Actually it could still be rising, if there are levee leaks from the river side. The river could indeed be higher than sea level.
High river levels are around 14 feet above sea level I've seen. I have no idea where it is at the moment.
I haven't heard about any leaks from the river side. If there are, then water will flow from the river downhill through NO to Lake Ponchartrain VERY fast. The river is several feet above sea level, 14 feet at high water. If there is a leak from the river, we will hear about that one in a hurry.