Im a long way from a professional but have a little bit of experience with ponding,
180 acres of runoff into a surface acre or two pond size is a lot, 18 inches or even 2' of free board is virtually peanuts for that much runoff, now depending on how steep that drainage is and what cover is on it will determine how fast all that water gets to your pond.
I have 15 acres of pond with about 130 acres of drainage coming into it and a big rain will bring that 15 acre lake up 8 to 10 inches, which scattered over 15 acres is probably enough to fill your pond several times from scratch, granted when my water comes up like that it might be spread out over another acre or two.
My point is, you will need to get a professional to design an overflow - spillway, to handle that much water, assuming that your pond was pretty close to full to begin with, and with very little free board, you will need a design that can handle the release of all that water, three creeks worth, in a very short amount of time. it can be done but it will be a pretty expansive, expensive project.
Good Luck!
