Pond Boss Forums Thread Like Summary - Need Advice RE: new pond overflow work

Hello all, 1st time finding this forum and new member !


We purchased a remote NC mountain property acreage with approx 1 acre pond in the woods, fed directly from a spring from top of the mountain which our property buts up against. Wonderful clean, clear spring water right out of the mountain head. We have been clearing the mountain laurel away from bank sides so more sun gets in, clearing dead standing trees on edges too, so they do not fall into pond and clog overflow, etc...

This pond was built around 50+ years ago and done extremely well with a 20' plus width just to top of the levy where existing overflow drops vertically below, that had an old 10" diameter corrugated metal overflow pipe down through bottom of said pond dumping into a clean out below the damn. Overflow on pond size has been crimped down to approx 4" diameter now too we find. This overflow pipe was damaged by neighbors who used the pond while it sat empty several years we found out, and at one point a fellow told us he hit the overflow pipe so hard it bent/moved to the angle it is at right now, which dropped water level 4-5' from where it normally was. I took many depth measurements from my inflatable boat back in November and seems we have approx 8' depth all around right now.

We want to raise this level up to where it used to be. We have talked to a couple local excavation folks who said run a 15" diameter slick wall type ABS pipe across levy (at height we want water to rise to) then down the levy into the existing cleanout basin below. Is this correct?.

In my research I have found so many types of overflow systems, I need solid advice here, as we need and want to save the pond because it is a very active ecosystem (frogs, minnows, turtles, coi fish even) and also had approx 176 trout (3 species) stocked last Fall and average trout are now around 22" in size ! Also it is the only standing water source around should anything happen to neighboring homes/farms such as fire in this remote area of Ashe County, NC and fire dept need something to hook into for a water source.

Is a standing concrete pipe say 36" diameter (with a steel grate top) set just offshore, in the mucky bottom fine (stabilizes it) , then run the 15" diameter slick wall across levy (from this drop inlet standpipe) and down to cleanout best way to ensure no future problems? What is best way to seal or reinforce bank area where pipe is now trenched on pond side to ensure no leakage against this overflow pipe or such in the future and water only goes down the new cast concrete overflow drop inlet, or is this not necessary since new pipe will be corrugated design on exterior and embed entire length in soil as it is run a cross levy and down to the cleanout basin below?

Thanks for any and all replies here.

Despite your information-packed post, I still don't think we have enough information to answer your questions.

Was the inlet of the overflow pipe bent down 4-5' below its original elevation? If so, then you cannot raise the water level until you fix that problem. Or is water entering the damaged pipe BELOW the inlet, or BYPASSING around the outside of the pipe?

If the 10" corrugated metal pipe is 50-years old, then it is almost certainly time to replace it. The most common procedure would be to drain the pond, dig out the old pipe, install your new outlet (of whatever type) through the dam, and then repack with good clay.

However, it sounds like you have a good fish population that would be ruined by draining the pond.

If that is the case, then the second best option may be to plug the discharge end of your current outlet pipe and fill it with cement. Then install a siphon system through the upper portion of the dam - which can be accomplished with only a partial drawdown of the pond.

Good luck on your project!