Pond Boss Forums POND CONSTRUCTION Building a dam Adjustable Spillway

Hello fellow Pondbossers,

I have a 10-30 acre (depending on the weather) body of water that is dammed and I think I want to bleed water out of it to control the water level and make wetlands down stream. The dam has a culvert that only flows water when we've had lots of rain, say once every ten years.

I'd like to be able to adjust the height of the water so I can flood down stream on a whim to promote growth of wild rice and the like.

A. Does any of this sound like a bad idea?

B. Can anyone suggest a spillway design?

I have a backhoe and I'd like some adjustment in the spillway not just an on-off valve.

-Jim

Do an internet search for "flash board risers".

Also Stop Log. Leland dam has a side stop log system, should they need it, although it's aluminum, concrete and steel.

Kinda hard to see here, but it's on the right of the heavier water flowing from the hydraulic dam:


A mini one of these would probably work. This is a pretty big lake tho.

I may have a closer shot, but will have to look.

Thanks esshup! That's exactly what I was looking for, just didn't know what to call it.

http://www.briggsconcrete.com/products/flashboard-concrete.htm

You're welcome. I've seen them with rubber gaskets on the sides too to help stop seepage.

Same thing as a stop log structure with sealed T&G Aluminum extruded logs to adjust the level.

This is what I have on my duck pond. Works great.

http://agridrain.com/watercontrolproductsinlet.asp

Thanks Chris. That was the one that I was looking for and all I could think of was Pond Dam Piping. They didn't have one on their website.

I remember 30 years or more ago on TV a dentist who had his office overlooking his large pond/small lake, and he raised and lowered the the water level with stackable boards that changed the heights of the spillway. He used the level of the water to kill unwanted vegetation in the water and then raised the water afterwards.

Looking at the agridrain site, I envisioned it working in the reverse direction so that water would flow out of the spillway, not into it. Besides being more prone to clogging with debris, is there a good reason people don't do it this way?

Best thing to do would be to call the manufacturer to get their opinion. With it on the back you will have more erosion with water spilling over the top and falling down. That could could be fixed with mounting the riser on a concrete base and placing rock all around the base so that the water doesnt fall on to dirt.

If it was set up this way, I would think a disadvantage would be the amount of water flow. Instead of the typical situation where the pipe gets full from a rain event and the elevation drop helps increase the pull of water thru the pipe, in this scenario the water is having to push itself back up to the same level as the pond. Perhaps someone who knows real physics/water pressures will chime in on this thought to confirm or deny it.

All sound like good enough reasons to run it the normal way. Thanks guys. Probably won't get to it for a few months. I'll update this thread then.

I think that it's not smart to create a large pond without draining possibility. It's nice that you thought about that now but there is only one problem - the water. You won't be able to work in the water and that means that draining the pond (at least partly) is the only solution.

Here's an example:

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=356281&page=1

The body of water is natural. The dam was put in place long before I was born. Thanks for the input.