Well... I go by the rule of thumb being that if it's being fed by a stream or river.. it's a lake. If it's runoff or spring without an outlet, then pond
Mine is only 4 and a half ft deep with a few levels and an alcove for the fish to hide from about 14ft round. I used all the dirt and a bunch of rocks to make a waterfall..
Did it all by hand. Took me a 4th of July weekend.