My new 1/4 acre pond would have made a great crystal clear swimming hole the first year had I kept it unstocked except for a few CC. With all the FHM, BG, RES, and now LMB, plus feeding, the visibility has been reduced to a few inches, and it has FA on the edges.
Plus, I think the abundant crawdads stir up the bottom.
If the main purpose is a swimming hole, why not build a lined, filtered pool of maybe 30,000 gallons or so?
Ponds around here will get too nasty to swim in within a couple of years even if unstocked due to abundant crawdads, aquatic plants, and algae, probably due to the runoff from fertility in hay and cattle fields surrounding them. Many ponds don't receive all their inflow water from the property they are on. YMMV.
