Hi everybody! I posted the following on FB yesterday and was almost immediately recommended to seek out Bob Lusk at The Pond Boss. I just watched an hour long video on pond construction on YouTube and I’ve gotta tell ya, Bob, I’m impressed. I’m confident you’re the guy who can answer my questions! I’d love to chat over the phone if you do that. Anyway, here’s the post:
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Greetings, y’all. I have a property near Carta Valley, Texas. I’ve had an engineer come out from the USDA to survey my place. He suggested a specific location and his recommendation was to build my pond at least 12’ deep and no more than 1/4 acre in surface size to avoid going dry during droughts.

One of my (our) concerns was hitting rock, but I was pleasantly surprised recently when my neighbor dug a TEST HOLE about 16’ deep and we hit zero rock. His excavator cut through it like butter. Therefore, I’m very excited!

As can be seen from the pic, there’s a lot of caliche material that’s porous. Water will run right through that, so I must line it. I’m not sure whether to line the pond with bentonite, clay or a poly liner. I want something that will last, but I also want to be able to afford it. I don’t really understand how clay or bentonite would stick to steep sides. I want about 1/4 to 1/3 of it to have a shallow end for doves and deer to drink, but I’d like about 2/3 to 3-4 of it to be a steep/deep drop off.

The purposes of the pond, in order, are:

1) Wildlife watering
2) Fishing
3) Swimming

I do have a water well that puts out about 15 GPM for supplementation, if necessary.

Can anyone recommend someone, or a company, in the area who can help me? As mentioned, I have the ability to dig the hole. Just need someone to finish it once the hole is there.

Thnx!!

Hello and welcome to the Pond Boss forum!

I help folks with pond construction, rehab, and leak abatement and as a volunteer moderator here my time is always free to the PB family. Feel free to reach out and we can hop on a call to strategize - happy to help however I can.

tj@hudlandmgmt.com

Thanks, TJ! Sending an email with my personal cell to tj@hudlandmgmt.com. Please call me when it’s convenient for you. If I don’t answer, please leave a message and I’ll call you back asap. Thank you!
-Scott

Scott, welcome to PB.

If you pack caliche or any other clay, it won’t leak. Well actually, all soil leaks but the goal is to avoid sand or use a clay/sandy soil mix. Clay expands when wet and cracks when it gets dry. The pond is best as a tear drop design with the deep end at the dam and shallow where the water runs in.

DeerTexas,

I hope your photo is a test pit, rather than a pond. I have only seen "ponds" with those dimensions used for water storage for fire fighting, or irrigation recovery, etc. Even then, they were either excavated in impermeable clay or had an artificial liner installed. (As you said, there is no way to get material to stick to the sides of such a pit.)

Most typical ponds with "steep banks" are built with about a 3:1 slope - for every three feet you move horizontally, the pond bottom goes down one foot.

That is about the steepest that you can easily pack clay on a slope. (It can be done with steeper slopes, but you need better material, expert crews, etc. to work past the normal boundaries.) Further, some shallow water is good. That is the access for terrestrial wildlife, and the plant community in the shallow water is the start of the food chain for your aquatic wildlife.

The caliche is not a problem, IF you have good clay on location. You must cut and slope back any caliche layers and cover with a compacted clay blanket. A 12' deep pond would probably need about 18" of clay on the bottom and up the side slopes. It needs to watered to the correct moisture content and compacted in 6" lifts.

If you can see horizontal layers in the topography of your property, AND your pond location is in the same "layer" as your neighbors', then your subsoils will probably be similar. However, if you are in a different layer, then you could have quite different materials. Further, a modern caliche layer can be developed based upon the groundwater level and the level of the roots of your cover vegetation. It can therefore cut right across geologic layers in certain conditions.

You definitely need to excavate some test pits in your preferred pond location. You can wet some of your material and see if you can make a cohesive golf ball with some of the stuff you think might be clay. If so, find your best layers and send some of that off to the soil lab to determine the clay content. (Frequently called a "grain size analysis".)

If you do NOT have good clay, and have lots of hard caliche, I believe it will be difficult to seal your pond even with bentonite. The caliche may exhibit large pores and fractures that are very difficult to seal. In that case, you might need to install an artificial liner.

Finally, the size of the pond is not the sole controlling factor to avoid going dry during droughts. The pond actually needs to be "right sized" for the watershed area that drains into the pond combined with the annual rainfall amount. (That is only the first approximation. The slope of the land, cover vegetation, soil type and permeability, and several other factors are also important.) If your pond is too small for your drainage area, then a big rain can blow out your dam. If your pond is too large, then it will only be full during the peak of the rainy season, and will be low or dry during drought periods.

I hope that helps with a few more items for you to evaluate.

Good luck with your new pond project!

Thank you! Definitely helps. Yes, that pic is simply a test hole. I believe a poly liner is the way I’m going to go. Even if clay or bentonite would work, it would have to be trucked in and I’m in a VERY remote area.

I’m hoping someone can explain my watershed to me so I can know what to expect. As I mentioned, I have a water well for supplementation, but I prefer to use it as sparingly as possible.

Do you have experience reading a topographic map? The watershed is all of the area where water on the surface would flow into your pond. For example, take the mid-point of a ridge by your pond, and water on your side will flow to your pond. Surface water past the mid-point will flow into the next valley over and miss your pond.

P.S. I have a planimeter (surface area tool) on my computer. Do you want to send my your exact pond site in a private message? I can give you a quick watershed estimate.

Pond Boss magazine once did an entire copy on liners. You might call the PB office to see what it would take to get a copy done.

I'm not familiar with the Del Rio area, but I have spent some time in the Rio Grande/LaJitas area. Rod's correct about how rain can hit hard and heavy between droughts, and potentially blow out a pond. If possible, I'd avoid a slope for the pond, and try to build it on a low flat area. The same with water shed. A wide water shed can provide the same volume of water without getting pinched, and potentially causing funneled damage.