Opening a DWG

I have a topographic map of my property and a dwg file of it. I could open the DWG in AutoCAD and save it to the desktop. Then when I opened that in SketchUp only the borders of the property opened and none of the contours. It’s only the contours I need. Does anyone have any suggestions?

Make sure that the contours aren’t an unsupported CAD entity.

https://help.sketchup.com/en/sketchup/importing-and-exporting-cad-files

If the contours were created in AutoCad Civil you would probably have to open the file in AutoCad with that AutoCad extension enabled, and from there, use what in some versions is called the Export to AutoCad command to convert the AutoCad Civil special objects into standard AutoCad entities.