I agree with Dave - there is no substitute for talking with your neighbors! (Plus getting to know them better is a bonus for future good relations.)

Even if they can't recommend a good pond builder, they might tell you one contractor NOT to use.

Also, local knowledge sometimes trumps expertise. If they hit caliche 6' down in the pasture adjacent to yours, then that is good to know while you are still in the planning stages and can move your pond site to a more favorable location.

Good luck on your project!