Did the gates look to be fully closed or partially open?
Looked closed.
There are two sets of gates at ANY lock. If both are open then the up level quickly runs to the low level (kind of a fluid thing). The River is much higher than any thing around the NOLA area except the Rivers own levees. If both sets of gates of the Missippi/Industrial Canal lock were open all that River water would flood into the Lake, over the canal and lake levees. and the city would flood fast. ALL of it - even the bits such as the French Quarter, which are above sea level.