The old pit was more than likely used to build up the base for an old abandoned railroad that runs along the property. I don't believe it was built to be a pond, however I do know that it used to hold water better than it does now. It has a clay base but it needs some trees and stumps removed and a core trench put in. There is a waterway that feeds into it that catches about 8-10 acres worth of surface runoff. The water level raised about 18" after a 4" rain event this summer so I think it has plenty of watershed to go bigger if I want. My main concern at this point is trying to figure out if going bigger is worth the extra expense or not.