OK there's you problem! I simply took a few minutes, imported the image from the PDF, and traced it - voila, clean vectors!
Looks like whoever converted it for you used a demo of "Print2Cad," and it did a remarkably poor job. I didn't even bother to open it in any of my CAD programs, simply opened it with Aspire. First thing I noticed is that there is a layer called, "Demo," which has their demo watermark on it, in the middle of your lake. Turning off that layer leaves a big hole in your lake!
Now to the real problem with the time estimates - the silly program created about a gazillion open vectors, trying to simulate the stroke of each line in the PDF image. Zoom way in and you can see what I mean.
If you really want to pursue this, you need to do a couple of things:
1) Learn how Aspire works - go through all the tutorials. It really helps to have a firm grasp of what and why things work. Looking at your DWG file, I can't see how you even attempted to create toolpaths for it, to get your estimated machining times...
2) I'd look into all the free places you can download real GIS data for just about anywhere. USGS comes to mind, but most states offer similar. Paul Rowntree wrote a program that makes this rather painless, actually. You can check it out, HERE.
You can download and use it, but he'd like a $25 donation, which is well worth it for all the work Paul put into it.
Hope this helps!