You think eagles have good eyesight; herons and egrets are eagle-eyed, too. Once they find your pond, they’ll put it on their “route” and visit for a feeding daily-to-weekly.
Herons/egrets can land/take-off in 2-3 steps; I had some with 8ft wingspans visit the Farm, years ago. They’re some impressive birds.
If you’re removing the pond, let the herons clean it out, or give the fish away to neighbors for their ponds.
Don’t spend the $ on heater/guard/netting if you’re getting rid of it.
You got that right about Herons and Egrets, Duck hunting, which I spent many hours doing in my youth, they stayed way away from the decoys...I assume because they could see us.