It does make sense. The area marked "dam" is where you intend to excavate, core the dam, use the best clay soils and build your dam, right? If so, you are approaching it properly. Don't move an ounce of dirt until you have finished your due diligence. If you haven't ordered our book, "Perfect Pond," you need to do that right away. It takes you through this process, step by step. Keep trying with the NRCS, too. Get USDA Handbook 590 about building ponds and lakes. Shoot the elevations...your idea is on the right track, but you need to do more homework. You might even think about calling Mike Otto and paying him to come help.

Teach a man to grow fish...
He can teach to catch fish...