Pond Boss Forums INTRO Questions & Observations Another spillway guard question...

My pond is about 2-3 acres with a 14" horizontal spillway with an aluminum hood over it. I have had few issues with clogs (surprisingly) but they're always at the entrance and easy to clear. We got a bunch of rain on Sunday and I found myself waist deep clearing the entrance on Monday and today, all sticks and leaves. I don't want to find myself in this position again so I'm planning on a spillway guard. Read several posts along these lines and I think I'll go with what Theo Gallus posted in 2008, if I may quote:
"Currently on my new pond, I have 5 T-posts driven into the bottom in front of the drain inlet in a semi-circle with 3 short T-posts tied horizontally across them at and above the normal water level."

Finally my question: I want to put some kind of screen in front of the T-posts and I have plenty of old cow panels laying around but the openings are 4" tall by 8" long. Do you think that is sufficient? I would think that would catch any branches which might cause a problem but allow the leaves and pine needles to go through. Tried to attach a photo; and keep in mind that the pond is high right now.

Opinions and options appreciated.

To revisit a blast from the past, the t-posts were attempting to guard an 8" drain tile inlet. (Probably not too long after 2008) I replaced them with a commercially available wire guard, pretty much identical to these.

At my other pond, the drain box is surrounded (on three sides) by 1/2" plastic mesh (similar to plastic snow fence, but made for pond use), about 3" tall (submerged to the bottom of the pond tied on to (wait for it) t-posts. Having a much larger surface area than the drain box, it has been immune to clogging that would impede drainage (although this particular pond doesn't get a huge amount of floating debris.

I think your old cattle panels will work just fine.

However, you might consider something solid (or with a much smaller opening) right at the top of your new screening structure.

You want to exclude all of the large and small floating debris that enters your pond after a storm. Make sure your panels stick up as high as your "flood" water level. Put some galvanized hardware cloth from the top of the panel to a few inches below the level of your hood inlet level.

After a storm, that screen will almost certainly be clogged with big floating branches (that could have clogged your outlet) as well as small floating debris like leaves and pine needles. However, your pond will drain the excess water just as efficiently through the lower 4" x 8" cattle panel openings.

Further, you don't really want the leaves and pine needles to stay in your pond. You could go out the day after the storm with a rake or pool skimmer and throw the unwanted debris over the back of the dam.

P.S. The proposed solution will be a little "ugly" in your pond, but quite effective. If that doesn't matter, then pursue your most effective "engineering" solution. However, on analogous projects on my property, my wife frequently gets a design veto, to trade off effectiveness versus how it looks. Usually a "trip back to the drawing board" can create a solution that makes ALL of the parties happy!

Had to look up galvanized hardware cloth. That should work fine. Thanks for the input.

I put galvanized hardware cloth over my pig-panel debris box and it rusted away in just a few years. It was submerged, but I thought it would last. A waste of time and money for me.

Agree. Hardware cloth isn't up to the task for ground/water contact.

2"x4" welded wire might gain you a year or two. Might.

Multiple down votes for hardware cloth!

Have to switch to Plan B.

The material at the top of the spillway guard does not even need to be permeable. The purpose is to block off the floating debris from reaching the outlet pipe hood.

Would treated ground contact wood last longer? Do you have any plastic materials in the back of the shed that would work?

Another idea would be to make a floating square of pvc pipe (to work like the opposite of the feeding rings used to contain floating fish food). If built correctly, that should work to block off floating debris outside of the square, and create a raft of crap that you can later scoop out of the pond.

I am a little worried that a stiff wind would push some of the debris over the top of the rounded pipe. Maybe attach some weld wire to the pvc, so that it sticks up 4" above and down 4" below the pipe. If that worked, then you wouldn't even need to drive t-posts offshore. You could just attach your "guard" on the shore at two points.

You could also pull it out for winter or if it is too ugly for a swim party.

I built a fixed dock over my outlet and closed off the sides with pig panels. Been using for 20 years. Only issues were beaver tunneling under the wire to clog the drain. Built a complete pig-panel box on the upside of a culvert in another location where beaver are active, and so far is working.

More good info!

I have observed beavers dragging cut trees of impressive size across lakes. What were your beavers using to clog your outlet once they got inside your panels? Did they manage to get some large sticks under your panels and incorporated into their project?

I have seen them use clay and grass to make wet "adobe" at my property that can withstand running water. The beavers then start working sticks into their project. I don't know if Jbbb has them at his pond, but I imagine they could completely clog a hooded pond outlet in less than an hour!

Beaver got moderately sized sticks through, but decided water lily rhizomes and pickerelweed plants were great material to clog my pipe. Learned they actually eat a lot of this stuff during the warm season. Really thinned out my water lilies before they were trapped out.

Ya know, plastic mesh is available from 3/16" openings all the way up to about 2" openings. That's what the fish cages are made of. No metal to rust, no zinc to bother the fish, no rough wire to damage the fish in the cages. It's available in rolls that are 4' wide.........

And if you bought a small roll of it use on your spillway guard, I bet you could find other uses for the rest of the roll around your pond!

I had some of this plastic mesh that got brittle and broke up, so make sure you know what you are buying. I made a fish cage but never got it out of the barn. After a couple years, it was useless even though it was kept inside.

The plastic mesh I put up 20 years ago has held up well.

Sadly, the place I bought in from hasn't stocked it in some time (or I'd post a link).

I've never purchased from these people, but this is the type of netting I was talking about.

https://www.industrialnetting.com/cage-netting.html

I think that is where I bought my netting.

I'm using an old chrome refrigerator shelf for a fish excluder on the outlet culvert. Fish don't swim on their sides, so I put the slots horizontal. The problem I have encountered using rectangular wire fence or hardware cloth is that it is difficult to clear.
There is a semicircle of large rip-rap in front of the grate to stop most of the floating grass and leaves.
If you have access to durable logs, like hedge, black locust, poplar, cypress you might make a log chain to float around the drain that would block floating debris and allow water to pass underneath.

Good thinking! I'm assuming you don't have flounder or halibut in your pond. LOL