I've been speaking on and off with the DNR about this for about a year, and there has never been a mention of any calculations required. I honestly don't think they want to know the watershed runoff flow amounts. (However, I agree with you that perhaps they should)
However, flow rates of the proposed system would likely be required.
I currently have a riprap where my current drain is. It would have to expand if I were to do a large spillway. However, there really is a very small volume of water that goes through that pipe.
I agree, more homework is needed, as I haven't decided on anything yet. I'm completely open to ideas. So far however, the siphon seems like the most reasonable, and cost effective method.
Otherwise, honestly, the pond does not add enough value to me, to make it worth $20k or another high expense repair.
