Its the original Corp of Engineers survey map of the pre-inundation area laid over a low water aerial photography making areas such as the north side of Mallard island and Van Hook bay even more interesting for the serious fisherman as seen in the included images.
HDS Gen 1-2-3
Elite HDI/Chirp/TI & Hook models.
Built-in Insight Maps will overlay the satellite image
Old 83 near Seven Sisters Islands
North Van Hook road and railroad grades.
Mike Peluso review
Sakakawea map is wicked good!