We have made some new maps from the old topo maps before the lake was dammed up. It shows everything like old Roads,Foundtions,Railroads, Ponds ETC. You can actually see thee old topo on your Lowrance unit. W have made a few screen shots of what the will look like. You can follow this link below. We will have several lakes in North and South Dakota coming soon.
Greatplainsmapping.com