Savage, welcome to the forum! You can go back in the historical images in Google Earth to see if the pond grows/shrinks in size. If there are bushes/trees in it, then the water is not very deep at all. If the pond is shared between other properties I would continue looking - any work you do to the pond could be completely undone by any neighbors that own part of the pond. i.e. managing fish, etc., etc.

With the pond being 1/3 acre it can't be very deep if you do the math in regards to the bottom of the pond slope. Plus the trees/bushes growing in it means that it isn't deep at all. Possibly too shallow for any sort of sustainable fishery.