I'm working on creating a 3D Model of a depth chart of a local lake so I can CNC it into a piece of wood for a custom cribbage board. I created the outline with the various depths in Adobe Illustrator. I imported that into Solidworks and created offset planes for the various steps of depth. I then want to create a gradual surface between each depth to make it look continuous and like a bowl. (I don't know much about 3D modeling. I'm having a friend of mine who is studying engineering help me). I believe he attempted to loft a boundary surface between the layers. The problem is we are getting overlapping since one layer is concaveing while the other layer is convexing and vise versa. It physically isn't overlapping since its a lake and there's a gradual slope to the bottom (conceptually). So is there anyway to fix this problem either by manually adjusting those lines connecting the layers together to make it not overlap or is there a command to tell it to connect from one layer to the other in a fashion that's closest to perpendicular.

Sorry if my terminology is a little entry level.

I've attached some screenshots of our work and problems within solidworks, a visual of the lake depth chart, the solidworks program file and the drawing file that was imported to solidworks. 

If anyone is able to help explain or if you could even attempt this solve this problem within solidworks that would be so awesome!

Thanks!