To my knowledge there is no detailed GPS map being produced by any of the
major map card makers such as Garmin and Navionics..I know with my current Navionic's SD cards I have to disable them and let my Humminbird 987si world map take over so that I get a good out line map of the lake. However with just the outline you get no detail and no depth contours..worse of all you also get no navigational aids to mark the major channels.
I suggest that everyone try and get themselves an Atlantic Mapping map of the lake ahead of time so they can study the lake's details. I wouldn't wait until the day I showed up to try and start totally blind..