Good morning everyone! I’m new here at the forum to posting but I’ve been reading for a while. I can’t seem to find an answer to my specific question through the searching so I thought I would ask and see what you guys thought. I own about 3 acres of hillside and would like to put a pond at the bottom of my property. My pond would need a dam belt but I would not like to do a straight dam I would like to do a slightly rounded dam only using half of my property at the bottom. I live in Ohio and my soil is almost entirely clay in my area. Feeding the pond would be a spring that runs year-round with a steady flow of water I don’t want any pond for major fishing but would like to add some small fish for the kids and someday grandkids to fish in. By my calculations using Google Earth the total size for the pond would be about 1/3 of an acre but the dam height would have to be about 12 to 15 feet at the tallest point since it is at the bottom of a hill. If you were going to undertake such a project how would you start and do you have any pointers that could steer me in the right direction. I’ve watched a lot of videos and read a lot of information here on the site and would like to do a core trench to help lock the dam into the ground. There are a few trees in the area that I could remove with the roots also to make room for the pond as they would encroach on the 3 to 1 ratio upon height to width. I appreciate your help and will try to get some pictures later on to post so you can see what I am working with thank you very much and have a great day
Last edited by esshup; 02/09/2310:17 AM. Reason: There is no "N" in dam.
Last time I built an Ohio pond (2007) you needed a permit (and an engineered plan ???) to build a dam that raised over 5 feet of water above the prior ground level. Contact your local Soil & Water (local) or NRCS (Federal) offices for info on the current regulations. They may also supply lists (but probably not recommendations) of nearby excavators (and maybe suitable engineers, if an engineering plan is required) for you to consider.
Scout existing ponds in your area and try to ask the owners 1) who built them and 2) does the pond hold water.
Thanks guys! Just curious I've been doing a lot of reading on here but can't find this answer, I know that building a pond over a spring can work both ways, it could fill the pond when the water table is high and act like a hole in a bucket if that water table drops. If I were to line the pond bottom with clay but happen to miss one spring point and the water table never drops below the water level of the pond in theory I would be ok right? The proposed spot for the pond is at the bottom of a hill roughly 30-40' in elevation below our spring that runs 24/7/365 with the same flowfor as long as we've had our home. Sorry for the quick sketch but wanted to illustrate what I was attempting to describe
As long as the spring flows more water than what is leaking out, you will keep the pond full. Think of a bathtub. Turn the faucet on 1/2 flow and pull the plug, the water level drops. Turn the faucet on all the way and the water level stays the same or rises.
Remember that it's not just one layer of compacted clay, it's best to do 3-4 different 6"-8" thick layers, compact each layer and then add another on top, compacting it.
The year-round spring with good flow definitely puts you into a good pond situation.
You say your soil is almost all clay, but the presence of a good spring indicates that there is at least one permeable layer of material in your subsoils. I suspect you have at least one layer of sand or gravel on your property. That is the layer you will need to cut off and effectively seal for your pond construction.
A properly constructed core trench will do that in the straight down slope direction. It will also anchor your dam in place, which is very important in your situation since you are building on a slope.
Based on your question about a curved dam, I assume you have realized that you will need a berm or levee on the sides of your pond where the impounded water level will be above grade. You will probably not need a core trench in the areas where your levee is only a few feet high. However, you will need scarify the soil below your levees to tie your levees to the original ground surface in a way that will seal against horizontal water flow. Also, if there is a permeable, sand layer in your pond site, then you must also cut and seal that layer so that impounded water will not flow laterally into that layer and then around your dam. Additionally, you will either have to do lifts and compaction in the center of your levees as you build up (like a core trench), or finish with a 12" clay blanket to seal the pond side of the levees. (That might be easier and cheaper since two 6" compacted lifts would be sufficient for the low parts of the levee.)
The worst case scenario (wild speculation on my part) would be if the sand/gravel layer became even better developed at the site of your pond. Geology in the real world is seldom uniform. Springs frequently flow water at the surface due to a restriction in the permeability of the layer transmitting the water. To expand on esshup's bathtub analogy above: the spring at a higher point on your hillside, could have the capability to flow at the rate of a 10" water main. If the permeable sand is restricted down to the equivalent of a 1" pipe near the location where your surface spring flow occurs, then the excess water comes to the surface and flows over the top of the restriction. Just like a dam in a surface stream when the water inflow rate exceeds the flow rate of the spillway pipe. I only point this out, because it is possible for you to construct a pond that leaks more than your spring inflow rate. Especially if the sand layer at the location of your pond turns back into the equivalent to a 10" water main.
Hopefully, the sand layer that supports the spring above your site will be readily apparent at your site during excavation of your pond. If you properly use standard sealing protocols with your good clay, then you should have no problems!
Finally, wet clay is no fun to work with during the excavation phase OR the sealing phase. Is there any way to build a spring box or pool up near your spring and use corrugated flexible drain tile pipe to divert the water around your pond site? (The 4" pipe is only $0.54/ft when it goes on sale at our local Menard's.) If you can do the diversion, that may save you many, many hours during the construction phase. You could even divert for six months prior to construction to perhaps even reduce the water in your subsoils a little.
Good luck on your pond project! A pond with a crescent dam, nestled at the bottom of a hill sounds like it could be a real beauty.
Thanks for the great information guys! When we dug on our property for our home basement we encountered 80 percent clay abput 4" of topsoil and 20 percent rock but not gravel size mostly odd shaped boulders and limestone ranging in size from 5" round to the size of a trash can, this was at the very top of the hill where I would think most of the "soil" would have eroded and washed down over the years. We never encountered a hard layer of rock just boulders surrounded in clay. As far as the spring drying up it's never let us down so far even last summer when we had abput a month between rains. we also have a well drilled that I've measured and it hits water roughly in the same spot as the spring. My thoughts about the leaking is that even if it did "leak" since the proposed pond would be a good 60' minimum below the water table and water seaks level as long as the water table didn't drop wouldn't the water from up hill push up into the pond trying to seek level? Maybe my thoughts are Messed up. I fully plan on doing the core trench and even running it into where the dam meets the hillside (all the way around). I also plan on compacting the bottom in lift a removing and large rock and using them for landscaping or rip rap. As far ad catching throw Ayer I currently have the spring pipe design running into a bathtub (a little rednecky I know) Andy then piped into the wood and away from the site of the pond to hopefully dry things up a bit. My issue is where the damage would be built is pretty mushy with I think another spring that I haven't located to pipe which knows will need fully excavated to get down to solid soil before I cut the core trench. My neighbor own some an excavating company And I would hire him to do the excavation but would like to have everything's planned before we start. Thanks guys
I tried to illustrate my water table seeking level on a drawing, whether or not it's true I don't know hahah
1.) You are correct about water reaching its own level.
2.) You are PROBABLY correct about the water level of the spring supporting your pond at full normal pool - even if you have a leaking spring in the basin of your pond.
3.) I typed that long explanation above for a low-odds, worst case scenario. If the permeable layer that is the water source for your spring is discontinuous, then the water level of a possible sand/gravel layer at the site of your pond COULD be much lower than the water level (potentiometric surface) of your spring up the hillside.
** Many springs are due to permeable layers in the bedrock that are capable of transmitting flows of water, usually combined with elevation changes. However, unconsolidated sediments can also create the conditions for springs. Typically via a continuous layer of sand or gravel that is constrained above and below by compacted clay. (Shale is a rock layer. Compacted clay is not.)
I think (low value, long-distance internet advice) that you are probably good to go on your pond project. I was just giving you some advice on what to look for during the excavation phase, so you can fix an observed problem before back-filling and compacting, and then finding out your pond leaks at an unacceptable rate.
Finally, if you do get a backhoe or small excavator on your property to pipe in your spring "bathtub", then you might consider a small slot pit in the approximate location of your proposed core trench. If you dig it when the surface ground is not mushy from recent rains, then observing the overnight fill up of your pit might give you some more information about the likely natural water level at the site of your pond.
Thanks for the well written and thought out explanations and things to look for. I'm hoping the ground will dry enough that I can tackle the project in the late spring/summer. I like the idea of the "trial pond" to check the water level! What would be a minimum depth that would support some bluegill and bass and a catfish or two. I'm not looking to raise trophy base just want somewhere for the kids to go and pull something out of the water
(They recommend 10-12' as the minimum depth for an area of 25% of the pond.)
Almost every pond construction thread on Pond Boss, includes the phrase "deeper is better". However, due to the geography of your site, every foot of additional dam height and levee height is going to add substantially to your construction costs!
Perhaps if you are digging in good clay, you might excavate deeper in a small area (10% of surface) to create a deep pool in the pond basin - even if you can't quite reach the state recommendation due to budget or location constraints.
I am NOT a fish expert, so hopefully if I make an incorrect statement below, then some expert will drop in to correct it.
Your fish listed above could probably survive their whole lives in fairly shallow water under normal conditions. However, I believe there are four main considerations to determine your minimum required pond depth for them to thrive year round.
1.) Drought. The pond must have enough depth for the fish to survive at the lowest water level experienced during the drought period.
2.) Ice over. In cold region lakes, the fish must have enough water under maximum ice thickness to survive.
3.) Plant growth. You need some plants to have a healthy pond. However, a shallow, weed-choked pond effects the ecology of the fishery, and the ability to enjoy the pond for fishing, swimming, etc. Generally, the pond sides need to slope down to "deep" water as quickly as feasible, to reduce the available sunlight for plants that start at the bottom.
4.) Future loss of depth. Essentially all ponds get shallower over time. Your pond construction depth must factor in some allowance for this phenomenon. The two biggest culprits are sediment washing in due to precipitation events, and leaves and other organic matter washing/blowing in and creating a muck buildup on the bottom.
(If your pond is mainly fed through clean, spring water and very few leaves will enter your pond, then this problem should be reduced for your site. However, you will almost certainly lose a little depth when a storm hits your churned up construction site before you have your soil re-stabilized with good groundcover plants.)
I speculate that if your spring does not dry up due to drought, your fish would PROBABLY do fine in a pond as shallow as 8 feet. I think the bigger risk would be overwhelming plant growth. Can you talk to any neighbors, or go boat or fish a little state recreation pond in the area? If the plants are heavy down to 9', then you are going to have to spend the dollars to create a 12' minimum.
I would note that there have been many posts on the forum from people wishing they had constructed their pond a few feet deeper. I have seen very few posts complaining about constructing a pond too deep. (And I think those were for ultra-deep ponds.)
Now that I have typed this long post, I think my best recommendation would be to start a new thread in "Questions and Observations", titled - Minimum Pond Depth in Ohio. We have lots of experts in the forum that manage ponds in Ohio. They should be able to give you some very good, specific advice. Further, I think knowing the "depth" number for your pond is your most important design factor at this point.