Another thing you will need to consider is where the water will come from to fill the pond. Will it be a groundwater filled pond or runoff or both. Sounds like you have runoff if you will be building a dam with higher ground above the pond. But the other consideration is if you have enough watershed to keep the pond at acceptable levels with your annual rainfall. If it is groundwater sourced there are issues of the groundwater both entering the pond as well as exiting (as in the pond going way low parts of the year)
Your local NRCS official should be able to give you information on your watershed area to fill the pond, groundwater levels, soil considerations in the dug area as well if it is suitable material for a dam, etc. He is likely even familiar with any regulations as far as permits, etc. you might need to stay on the good side of the law. Our local NRCS guy is a good one. I suspect the quality of information you get will be commensurate with the ability and willingness to help of your local government agent.
If you see other ponds in the area, talking to the landowners to see what their issues were might be worthwhile also.
One acre is a pretty easy size to do, especially if the area is open all the way around the pond. Our main pond was three acres, but we were limited on where we could push dirt so had to move more dirt that we would have needed if the dam area had not been bordered by a creek.
To give you an idea of watershed size importance, below is a picture of our pond. Our house is on top of a hill. The natural watershed into the pond was only about 5 acres. Not enough to keep it filled during dry periods. So we needed to build a terrace in the adjoining field to bring in another 5 or 6 acres of water. It is still marginal, but we get about 42 inches of rain a year, sometimes in large events, so even though the pond is probably 18" low now, it will recharge pretty quickly when we get in a wetter period. Size of watershed and annual rainfall (as well as size of rainfall events) are important in a pond filled with runoff. Picture shows added watershed via terrace added to farm land field in the right hand portion of the picture. Building sites are on the peak of the hill.
