Mr. Ed, I have never seen the 40 acres your parents use to own, however, without the advantage of looking at it I can still assure you of two (2) things, 1: The pond had a natural clay "possible stone" liner and 2: There was some water source feeding the pond, creek, underground spring, natural runoff, gutter, etc.

As far as the fish size you mentioned "except for the catfish, 30+ inches, they were introduced into the pond" that is very possible with bass as they are very fierce competitors. All in all it sounds as though there was a very balance eco system in place during the time your parents had the property. I have know idea how old the pond would be now, however, unless someone is watching and caring over it and tending to the backfill problems, winter fish kills, water pollutants, algae take over, droughts, and pressures from anglers, it to will eventually be a mud hole. All ponds go through stages and most ponds are eventually done in by erosion.

Your original question was concerning pumping water into what you referred to as a seasonal duck pond using a solar pump. Ponds are somewhat a forte of mine, so I felt the urge to be helpful, I didn't want you to get all carried away about pumping water when you didn't even have the main ingredient "a hole in the ground that can contain water" I guess in your case trial by error would seemed appropriate.