Assuming we are only considering climate, If the pond gets 30+ days of ice cover, I would classify it as northern pond. A refined classification would put a WVA pond and those with similar latitude as "intermediate".
Technically if I was establishing the north vs south pond classification, I would create a scale that was similar to vegetation plant hardiness zones. Incorporate number of growing days with temperatures above 50F.
https://garden.org/nga/zipzone/2012/
