After doing a little research of my own I found your assessment to be correct. I have 200 to 300 acres of watershed and based on 8 acres per acre foot of water and a runoff factor of 60% I calculate that I would need to build a 4-5 acre pond in addition to having a good spillway. Does anyone see a flaw in this logic? I was not planning this big of a pond but if the watershed will support it I may give it a try! I have attached a new pond layout based on the above and some of the reference data that I used in my calculations.
