Pond Boss Forums INTRO Questions & Observations overflow pipe screen HELP!

I think MOST of us can safely put up a fence of some sort that will stop MOST of the fish from leaving our pond MOST of the time. Change any of those three MOSTs to an ALL and you're looking for trouble.

I believe my barrier, that is shown in the thread Brettski linked to, will stop almost all fish exceeding the 1/2" screen size from being washed out of my pond in anything short of a once in 5-10 year rain event. I put it in so that it only takes perhaps 8" of water level rise to by-pass the fence. This is at about 18" below the point where the secondary spillway (overflow) starts to pass water, which in turn is at least 18" below the top of the dam.

So that all the qualifiers and provisos (that I can think of) are in the open, the pond has a 10-11 acre watershed feeding it and has only required an 8" drain pipe to handle all drainage. The secondary spillway has only had water once, when the pond was new. Before I cut the thin upper end collar off the drainpipe, it collapsed during a heavy flow and blocked probably 2/3 of the hole. Since the collar was removed, all flows have fit down the 8" drain without any overflow.

One additional important fact is that my pond has a very small amount of vegetation in it to possibly block the screen. Most of what it does have is FA, which seems to float if loose and has only blocked the screen at the surface level. When that happens, the water keeps on flowing out through the submerged part of the screen.

P.S. I put the screen in when the pond was new, my fish were small, and my amazement at the sheer numbers of fry, fingerlings, and juvenile fish produced by spawning had not yet been established. If I hadn't have done it then, I wouldn't bother to do it now.