My two are mostly under 1 acre, except in spring when one grows. In fall it is closer to 500sq ft.
I would think that you won't have a problem with ice pushing on those piers BUT you might have a problem with the ice grabbing them and lifting if the water rises after the pond freezes. Around here this happens to decks when they are on sono-tubes. Cover the rough concrete piers with something that the ice can either slide up, or grab and lift without moving the pier behind it.