Is the lower right part of the map (darker shade) the flooded portion of the city?
That is not a current photograph, but rather a composite of old satellite images. The shade variation is due to the different times or cameras that took the photos. Pretty much the entire area you see is flooded.
It's all flooded, for miles around.
This page has a link to a video of a helicopter tour of NOLA and surrounding flooded areas:
http://www.wwltv.com
Look below the photo for the first link, "Aerial video of city".
The video has been split into several parts, 1 through 5, due to its length.
The reporter could not believe the extent of the flooding.