LakeMaster is re surveying all of the N. Mississippi lakes now. They have also done KY Lake and several others in MO. Not sure of the rest, but it might be better to wait on them. Navionics doesn't have good coverage on shallower areas because they surveyed the lakes at Winter Pool, when they were low. They couldn't get to those areas at that time. Like RG said, the Insight built in the Lowrance units works well in these areas, but doesn't show the contours as well as Navionics.