I have a site 15-20 acres in beautiful rolling wooded hills that I am trying to dam up. I have civil and soil engineers and NRCS help. I have done an intensive soil survey. Result: Everyone agrees the dam will hold. The NRCS says that due to the sandy nature of some of the sides of the pond that the water will just escape there. Does anyone have similar experiences that they have worked out? The dam itself would be 25ft high with a 20ft water depth which just increases any expense dramatically. I have put alot of time and $ into this and I feel like I am no closer. ALL input would be GREATLY APPRECIATED! THANKS.

What area of the country is your site located? (Good idea to fill out your profile). Is the pond 15-20 acres or the total land site? Do you have clay available on-site? I don't have answers for you but I'm sure those who can help will want more details.

Like RobA says, B Relan, go ahead and put whatever info. you're comfortable with regarding your location.

There's so much area specific information that you can get from the folks here.

Also as RobA says, it might be a good idea to line the sides with clay. I have no pond building experience but so many here do, and they'll chime in. Sandy soils can make the project fail.

Welcome aboard.

Thanks guys! The size of the lake itself would be 15-20 acres. There is a large knoll at the top of the site which would be excavated to build the dam, and get the lake to this size. This material is solid clay, perfect for the dam. In areas around the site theres good silty clay with places of clayey sandy gravel. The land itself is in Louisiana. There is an 8, 30, and 190 acre lake between 1 and 5 miles away. I am looking for a minimum of 15 acres because of what I've read about needing this surface area to get a healthy population of bass and crappie(sac a lait).

My thoughts, on your a 15-20 acre lake site is that maybe you should open a sand/gravel pit and sell of some of the sand/gravel to off set your cost on building it. If you sold the sand/gravel you could than easily push the clay from the bottom making a clay seal up the side walls. The key is do you have a market to sell the sand and gravel?

I have thought about this also. There are actually several gravel pits in the area along a live creek my property borders. I'm sure that I could sell it off in markets around me. Will the clay adhere properly to the side walls of some sand and gravel? I am also in the process of having someone determine if the rainfall in the area would be equal to or greater than the amount lost to the sides. Or maybe digging a well or possibly pumping in the water from the creek to keep up with the loss. I am scared to think of the cost of lining a 20ac site with a 20ft depth of water with clay. I have even thought of downsizing some of the depth to make it more viable. Maybe I need a lottery ticket.....

I've never tried to line the sides of a pond so can't be sure of anything. However, I don't see what would make it adhere and overcome gravity. Maybe if you built it with a really gradual slope, it could work. If it were me, and it's not, I would either downsize back to good clay or possibly find another site.

Anytime you deal with soils that have some difficulties (like your sand/gravel sides) you have the possibility of a big swing in cost dealing with them. On a bigger pond, I don't see how the potential cost swing wouldn't be equally big.

If you have sufficient clay to line the whole pond a couple of feet thick, figure that approach for the cost. Hopefully it will be the worst case estimate IF the leaky sandy soils are such that clay can be packed on them easily. Like DD points out, lining clay onto the sides of a pile of pure sand or gravel would be virtually impossible.

You're planning a big pond (or a small lake); a large number of test holes are also called for, to try and determine the extent of the clay, extent and nature of the leaky soils, etc.

To line 20 acres with 2ft of clay is approximately 65000 yds. At a dollar a yard thats 65k + the cost of the dam.

Wow, I appreciate that calculation. It seems like that is one of the roads I will have to take. My engineer just told me that someone in the area is creating a 200ac lake. They are going to line the whole thing. Lake is 4 miles long, whew! I don't know if they are lining with clay, bentonite, etc. He is going to find out for me. If I could get it lined in that price range, it's done. I dream of having an environment to plan and grow and watch.

I paid 35k for a 4.5 acre pond with a 20,000 yd dam last year. Price was 1.30 per yd which is the going rate around these parts with the increase in fuel prices. I'd think a 1.00$ yd or a little better could be negotiated being that is going to be a large project and the contractor will be on the job for several months they tend to work for better rates. Good luck with your project.