I first hired a guy that builds ponds to clear and make the pond for me. There's a small stream that flows through the middle of the pond that can fill it when I close the drain pipe that runs thru the dam. This works if there has been sufficient rain in the fall. If there has not, I had a 6" well dug near the pond with a discharge into the stream that will allow me to fill the pond on demand if needed. It pumps about 350 gallons per minute. I also have four risers for irrigation through the middle of the pond so that I can irrigate whatever I'm growing in the pond in the spring and summer. I've grown milo in the pond some years, but it just doesn't seem to last for feed as far into the duck season as I need. Corn also seems to provide better cover for the ducks. I also made a small island in the middle of the pond, something that many duck pond experts said the ducks would like.
Everything considered, it all really works.
As for ducks, by December I usually have about 500-700 that feed in the pond twice each day. They feed each morning, of course, but feed again each afternoon before flying over to my roost pond, which is about 1/3 of a mile away from this feed pond. I don't hunt the roost pond, or this one in the afternoon, even though the ducks do come in to it in the afternoon during legal shooting hours. This careful approach lets me hunt the ducks about once a week without disturbing them.
It's fun!