Pond Boss Forums Thread Like Summary - Overflow tube height

New to your site!

Purchased a farm in south central Iowa in December, 2020 which has a 1/2 acre pond on it. It's 9' deep and I would like to get it a little deeper. I have a 6" diameter spiral metal tube going thru the dam at about a 45 degree angle. The banks can handle a increase of 2-3' deeper water so my question is how can I add an extension this metal spiral over flow tube to raise the level up 2-3'?

I've heard 11-12' is a nice depth to have?

Last week I stocked it with 150 BG, 50 LMB, 50 CC all within 3"-4" range and minnows.

No electricity near by but would like to add aeration to it like solar or wind....thoughts?

Thanks in Advance

Another consideration is that your pond should have some freeboard between the normal pool level and the elevation of the emergency spillway (or the top of your embankment if there is no emergency outlet).

If you install a new overflow tube and raise the level by 3', then a big rain could go over your dam while the 6" drain is not keeping up with the inflow. That could wipe out your dam and fish population.

There may be a very good reason for the pipe elevation they selected in the original pond design.

^^^ What he said!

I should have added that you almost certainly need to open a drain valve in the riser for the winter in Iowa. (Which will draw your pond back down for winter.)

Looks pretty rusty. Might think about a new pipe if it is close to giving out.

Be careful with a riser on the outflow if you live where it freezes.

Not cheap, but might work

https://www.agridrain.com/shop/c85/...02/inlet-water-level-control-structures/

ISC,

It is also possible to control your water level by controlling the elevation of the drain tube at the discharge end of the pipe.

It will cost more money for pipe, but it may be much easier to install.

You can install a 45 ell, then a little straight pipe in a horizonal run, a 90 ell, and then a pipe riser that is vertical and extends up to your desired pond elevation level.

In this scenario, the next time a water inflow event raises your pond level, your outflow tube will fill with water. Any excess water above your outlet elevation will run out of the tube, but your pond will stop draining at the new level.

You can even make a variable water level by making a "turn down stand pipe". Basically, your highest water level is when the outlet pipe riser is pointed straight up. As you "turn down" the pipe by rotating it at the 90 ell, you can select a lower water level elevation.

[It would be very difficult to make a turn down stand pipe with spiral metal culvert, but it can work for other piping material for people in a similar situation.]

Good luck on your project!

11' or deeper is nice to have, but not that important under average pond circumstances. I can think of two benefits...longer life as it fills in over time and a larger holding capacity given that it's aerated.

I also think the freeboard needs to be investigated further, but we are lacking those details.

If I had to make that pond 2-3' deeper, with my very limited knowledge of doing so (read - I have no authority on the subject), I would get another piece of pipe like the drain pipe (size and style if possible) to extend it on the pond side. Then...weld it, epoxy it, tar it, wrap it, tar it again, etc....and then build a form around it a concrete the whole works. I'd bet that it would outlast the existing rusty drain pipe. Like I said...I have no experience doing this and would not recommend raising the water level until all the info is explored.

A second thought would be to put in an all new pipe 2-3" higher and have the old pipe dug back, sealed off, and abandoned. Once again, I have no idea how to seal it off besides "weld it, epoxy it, tar it, wrap it, tar it again, etc"...lol

Here's a flip and post of your photo...

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