Pond Boss Forums INTRO Questions & Observations Pond under construction now...???'s

I have a pond currently being built right now and I have a couple of questions that I hope someone here can help me with. Due to the depth of the main ravine that we are damming up, we knew this was going to be a deep pond, probably 28'-30' of depth.

However, after the builders have completed about 80% of the digging it is apparent that the pond is going to be even deeper than that, more like 40' deep. The surface acres should be right at 2.6 to 2.8 acres. With that type of depth are there any special considerations that you would make in terms of creating and/or placing structure in the pond?

I have a fair amount of habitat structures that I have prepared that I will likely be placing in the pond in the next 5-15 days, once it is complete. For the most part, these structures are about 4'-5' tall and I was going to place them in about 10' of depth, so the tops of the structures would be about 4' or so below the surface.

Given the depth of this pond, would it advisable to place some structure in deeper water too? If so, how deep? Is there any way to estimate where the thermocline may end up in a pond this deep?

What, if anything, would you do about a pond that would be this deep? Most ponds in our area would probably be about 20'-22' deep, so this is out of the ordinary. TIA.

Well I guess it depends on what your gonna have in the pond? In the winter your LMB if you have them will go deeper as the water gets more saturated with D.O. You could have LMB in the 30 foot range. Of course in the spring they will come up shallow and mid summer like now they will hold a lot in the 12 to 20 foot range depending on where your pond has the best D.O. in it. As your pond warms up in the summer it will stratify and parts will become low in D.O. so fish will move up to the better D.O. in the column. So anyway yes I would put some structure in the 20 foot range if possible. Not sure I would go any deeper then that though with structure... but that's just me.

RC

To me it depends on whether you plan to put in aeration. I did the dam across a ravine thing. It is a wooded ravine. Sides are steep. The thermocline during the summer is only 6-7' down or so. I just put in aeration (at ~9' for now), and when I cranked it up for a few minutes the first time, I could smell the bad gas coming up and the water was cold. There aren't going to be any fish down there this time of year. While there will be fish deep during the winter, most folks aren't fishing then and the fish aren't doing much. If you do something to make more of the water depth habitable, then adding deep structure would have value.

Where I am located in SE Iowa, the normal stocking regimen is LMB, BG and CC. That is what I was planning on. I would love to be able to fish for nice crappies too, but a lot of what I have read about crappies in small ponds is causing me to NOT put them in.

I do plan on adding aeration in a year or two. My sides should mostly be at a 2:1 slope, with some a little steeper. The main depth comes from the creek channel/ravine that is in the center of the pond. There will be a LOT of deep water there, but also plenty of "normal" depths, say down to 10'-12', around the perimeter of the pond.

Although it is in a ravine, there should be fair to good air flow across about 75% of the pond, as the dam is being built tall enough that the water level will subsequently be high enough that the winds should hit the surface fairly decently. It will not be the classic tree-ringed pond, only a few trees along the waters edge will remain.

I'd consider against going so deep. Increase of depth from 28-40' is almost 11 million more gallons of water needed to fill and keep the pond full. Depending on your watershed or irrigation situation this could prove problematic - could be very costly to keep it filled or if you rely on precipitation and watershed to fill you could be left always praying for rain and a half full pond. Also, if the pond stratifies during the Summer, which I imagine it will considering the depth, you'll have a lot of water devoid of O2 and fish - potentially expensive but worthless water. Another concern I harbor is the deeper they go, the more money is spend on construction, and there's an exponentially higher risk of hitting suspect soils, gravel, sand, etc. and that much more area to plate and compact clay around which isn't cheap either. Sounds like a great plan for the pond construction company, but potentially very expensive for you.

For the species you list, depth of 12-14' is more than adequate. Considering the fact that construction cost are in part based on cyds of dirt moved, it's possible you're looking at 200-300% more work based on that depth and possibly 200-300% more in costs.

This is just my initial take based on the information provided. Probably more to the story...

At least the extra depth will be insurance against drought, provided you won't have a bottom leak. A guy near here had a dug out pond made 45 feet deep, and it won't hold water.

Hmmmm....the problem with not going deeper is that they pretty much already did. Yikes! The area that my farm is in does have a heavy clay based soil, making pond building generally almost bullet proof in terms of holding water.

I can say that the massive hole does still look like unending clay to look at it. (I know that isn't the same as perc testing the soil.) But having read your concerns, I would have to say that I am now a little concerned.

As far as expense...it's a bid job and I haven't authorized any additional expenses...so I hope there isn't a surprise conversation in store. Sheesh...pond building is stressful.

Sorry Dave, I hate being a downer just presenting all details I can. I work with a lot of guys in NE and IA to help them source land, find pond builders, create stocking strategy, pond management etc. and this is just what experience suggests as concerns. What's your watershed size? A pond 3x deeper than normal is almost just like having a pond 2-3 x larger in terms of surface area. In Eastern NE our formula is 33 acre watershed to keep a 1 acre pond average depth of 6' full based on our annual precipitation of 29". I would imagine you receive more precipitation than we do, but for a 2.8 acre pond with an average depth of 20'+ here in Lincoln it would require 250 - 275 acre watershed to at least fill initially. Your pond guys should have reviewed elevation maps prior to building the pond and remained within parameters which would allow your pond a shot of being full pool most of the year without supplemental irrigation. I can't imagine they neglected to do so, but I'd ask them ASAP to review that with you. Again, a 40' pond half full is a 20' mudhole - unsightly and potentially dangerous.

what type system do you have in place for the water to exit the pond? a traditional stand pipe with trash rack would be very tall. i would do a reverse standpipe. put the thru pipe right on the bottom, let it run thru the dam and turn up on the backside. the height of the pipe on the backside would would determine the pond water level. it would always be drawing the bad water right off the bottom. my trash rack pulls water about 6 ft from the surface. i have a separate pipe with a valve on the dry side. i open it from time to time and the water is really fowl. the deepest part of my pond is about 15 ft or so.

i have a different thought on the depth than some. if you have 2 surface acres, once it is full it doesnt matter what the depth is. if the pond level drops a ft, it takes the same amount to fill it back up, no matter if pond is 10ft deep or 100ft deep. the extra depth is great insurance in my opinion.

Why did it go 40 ft. deep? If it's all clay you could have them put some back in. Or maybe it was needed for the dam?

I think like Scott. I'm in an area where rainfall is a little questionable. We either have droughts or floods. To me, it would be hard to have a pond that was holding too much water. But like TJ says, the wild card/key is the runoff area that is needed to fill it. When my pond was built, I got a lot of water from an absentee neighbors land. He sold and the new owner plowed it up and planted grasses to more effectively hold moisture on his land for cattle. I can't blame him for that. I'm hoping that our recent floods might have washed out some areas that will help runoff for me. I generally tell aspiring pond owners that they need to be sure that they control the runoff areas.

In normal times, the bottom water is always junk water that is too deep to hold O2 and is unusable when it comes to supporting life. But when the water level drops, sunshine and wind will take over and provide O2. My 17 ft deep pond got down to 1.5 ft during the latest drought and, although it was a muddy mess, fish survived.

DD1, that is exactly why when I renovated my pond I dug it to 22' deep. Water table pond, and the pond level can fluctuate around 6' from full pool to low pool.

So, in a dry year, I still go through winter with plenty of water depth for the fish.

With the suggestion that I may need as much as 250+ acres of watershed to support that size of pond, I began to think of other ponds, including some that are as large, or even significantly larger than mine, and I cannot think of one that has anywhere near that amount of acres "above" it.

My pond will have about 30-35 acres of watershed by the way I look at things. I know of an 8+ acre pond that is about 25' deep that probably only has 40 acres draining into it, and it is always full. There are several ponds in my neighborhood, including multiple 1.5'ish acre ponds that have only 8-15 acres draining into them and they are always full. At least three of these are on neighboring properties.

Is it possible that local conditions are different enough that I shouldn't be so concerned, etc? I do realize that my additional depth changes the equation, but, and I may not have made this clear, that max depth is essentially limited to about 1/7th of the pond where the old creek channel/ravine bottom is. (Note - the creek channel was scrubbed by the dozers and then partially refilled with clay, so I don't feel like it is likely to seep/leak.)

I appreciate all of the advice and thoughts, but I am just trying to sort out what I should do at this moment...as the dozer operator texted me today and said that the dam is done. So if I need to fill in that valley, etc, it's going to have to happen right away I think...because I think it is officially a pond today.

Well, if it's officially a pond, start doing rain dances.

Once you fill the pond, keeping 2.8 acres topped off will not require a watershed that size, I was citing metrics based on your initial fill and the fact a 40 ft deep pond will require 11 million more gallons of water to fill than a more normal depth. A lot depends on your annual precipitation, per my previous post. From the sound of it your neighbors don't have issues keeping similar sized ponds full with smaller watersheds than necessary in NE, so you obviously are dealing with more precipitation. Where I live, 40 acres of watershed could keep a 1.25 acre pond full without supplemental irrigation from a well - sounds like your scenario is different.

You've heard different viewpoints on the depth in a pond - for the species you are considering anything over 14-16' is unnecessary especially if your local ponds are always topped off and precipitation doesn't seem to be scarce. Again, the only negatives I find of having such a deep pond is the additional time it will take to initially fill, the fact that a lot of that water could be devoid of DO during late Spring into early Fall so essentially useless for your fishery unless you aerate, and if it cost you more to excavate to that depth - it would have been, in my view, a waste of money.

I don't know I'd personally go to the expense of filling it in to 20-25' depth, just trying to illuminate some facts regarding the current depth of the pond so you are aware. Your neighboring ponds serve as a great standard by which to judge the performance of your own pond in the future, regardless of the statistics anyone quotes on the forum. Apparently watershed and precipitation aren't going to serve as issues down the road, so that's great news. My point was that the pond construction company should have reviewed those details with you initially as they are very important for many of us across the country who aren't blessed with your scenario of plentiful precipitation. IE: "Based on your annual precipitation, a pond your size requires x amount of watershed acres to support...."

One of my neighbors has 1 acre, 4 acre and 7.5 acre ponds in a chain on a ravine. They are pretty deep, maybe close to 30 feet for the larger two. He has 400 acres of watershed, and it is WAY too much watershed for his needs. Every time we have a big rain, all three quickly go over the emergency spillways. The watershed is a mixture of wooded ravines and pastures. We normally get about 48 inches of annual rainfall here. For the flow he gets, he needs about 40 acres of water.

your pond may take longer to fill than a shallow pond, but once it is full it will be no harder to keep full than a shallow pond with the same surface area and same drainage entering it. its all about surface area after it is full.

I would not worry about it being deeper. A pond never gets deeper on its own, but it always gets shallower over the years. Being extra deep just gives you many years of not worrying about sediment making it too shallow.

Deep also gives you some good options that a shallower pond might not, but also come challenges.

On the options, you can always add aeration and by choosing the depth of the diffusers create more usable water for the fish. A challenge might be that it will be harder to have structure in the middle of the pond if you wanted it. Long ways to the bottom if you want to place something there for fish habitat. On the other hand, there would be possibilities of floating islands and floating anchored structure. If you ever have to pump it dry to kill all the fish and start over, more water will be more of a pumping problem.

If i had to choose between a pond too deep and one too shallow all other things being equal, I would always choose the deeper one. I would like to have your problem.

In your situation with your precipitation and watershed, I think you are good to go.

Thanks everyone for all of the input, I am not sure much can be done now...as the builder texted me today and said that the dam is closed up and it is raining tonight...so now we'll see.

Oh, final max depth measurement = 38'.

On your structure question, If you want something out in the deepest part of the pond, I would consider putting some 4" diameter earth anchors in the pond bottom with ropes or cables with ropes attached. Then create structure that floats and will remain floating and not water log. Attach this structure to the rope/cable and use the length of the cable to determine how far below the surface the structure remains.

You can get earth anchors at farm stores or order them on line.

I have numerous permanent moorings in my pond that I can attach my boat to. We get lots of wind and anchors tend to get hung up on structure. I like to hook my boat to the mooring to fish from. If you made floating structure like I am talking about, it would be easy to use a rope and float to mark the structure as well as a mooring for a boat to fish from.

Do it before the pond fills or learn to scuba dive or make friends with a scuba diver. Thinking of and planning for these things is much easier to implement in a dry pond.

Unless it fills all the way on the first rain (hopefully not), you can still do anything you want down to the water line. So you may have some time still to do things.