Get in touch with the NRCS as soon as possible to begin your planning phase. They'll design the dam, calculate volumes of dirt that need to be moved and help you. Do it now, because those folks are typically overworked, hard to schedule and need the lead time nowadays.

Just because you know an excellent dirt mover doesn't mean he needs to do the work. I know a pilot, but wouldn't dare want him in control of a jumbo jet. Experience pays, even if it costs more.

If you choose to pursue your dirt mover to do the work, then I'd call Mike Otto for consultation. He's been a great lake builder for more than 40 years. If he can't convey good knowledge to your favored, no one can.

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