I hired a grader today to start my 1.5 acre pond in 2 weeks. We roughly have 55 acres of watershed and he was saying we need a 24 inch pipe. That sounds big to me. Also, what type of system would you guys recommend? Everyone seems to go with a syphon system, but I want to be able to drain it if I need too. Sorry for the silly questions. I am new to all of this. Thanks in advance for your help!

I am not sure what size pipe you need, BUT you are right down the road from me! I would much rather be too big than too small. To Mother Nature, size DOES matter!! Good luck!

Your local NRCS or state Soil & Water office can probably provide the best guidance on what size drain pipe you need, based on the vegetation type in the watershed (tilled field, grassland, forest, or God forbid parking lot) and local average and worst case rainfalls.

Like Theo said, all of the above issues will make a difference including how much free board you have and obviously too big is way better then too small, that being said unless most of the 50 acres is paved, 24" seems excessive.

The 50 acres is almost all wooded. I am thinking 18 would be sufficient. I called the NCRS and they are not doing farm ponds anymore!

Just a 12" pipe will flow a hell of a lot of water and would lower your 1.5 acre pond down quite a bit just over night.

Is there some reason to think this pipe is needed to also flow a river from the country side?

Here's the question;
Where does the water go now when it rains, is there a pop up stream of some sort?

I have a 12" pipe in a 2 acre lake with probably 70 80 acres of runoff in woods and in 20 years have never reached the emergency spillway, with a couple feet of free board.
rule of thumb, every time you double the diameter of a pipe you quadruple the flow approx, so a 24" pipe would carry the same amount of water as 4 12" pipes.