Pond Boss Forums POND CONSTRUCTION Building a dam Skip the spillway?

So much depends on what kind of rain events and the amount of runoff you have. For example, a very small pond with a very large runoff area had better have very good water control leaving the dam. A small pond with relatively small runoff area, not so much so.

A half acre pond is not so big. If it is fairly close to the top of a hill and has just a few acres runoff, then your builder might not be expecting there ever to be huge amounts of rain flow across the top. I do agree with others though, a dam will rarely stay level and the water is likely to find a low spot and start washing there.

If you have 40 acres running into that half acre pond and sometimes get 12 inches of rain in two days like we can get where I live, better have a very good emergency spillway.

I'm in no way an expert on these matters. Just a farmer with quite a few years of experience with terraces and waterways handling water flow. How much flow there will ultimately be makes all the difference in the world.