Pond Boss Forums POND CONSTRUCTION Building a dam How deep is too deep?

I know with lakes and reservoirs there is a level at which below it there is little oxygen and I wanted to know if this applies to ponds that are built very deep such as 20-40ft. I would think that a strong enough (capacity for water volumn)
pump system would alleviate this problem all together but is there a depth the becomes counter productive to most pond owners goals.

Installing an aeration system with a bottom-diffuser will reduce or toally alleviate problems associated with low levels of dissolved oxygen.

For a reliable aerator, check the ads in the current issue of Pond Boss.

Mark McDonald
Editor, Pond Boss

Here's another angle...fish production occurs mostly in the top 4 feet of water. Theoretically, water deeper than that is wasted, in terms of fish production. The fact is, water needs to be deeper for other reasons. In arid eastern Colorado, western Kansas, ponds must be deep, or they will dry up. In the north, depth helps fish survive the winter due to ice and snow cover.
The only other reason to build a deep pond is if the terrain dictates it, a gulley or wash. Ponds are designed, including depth, based on the site and goals of the landowner. Be aware of the site, and if a contractor tries to build a pond deeper than it needs to be, he may be looking to make a buck, rather than create a pond in your best interests.

Bob,

I thought of one more reason for a deep pond that you didn't mention. In my case I have a pond that is deep for it's surface area to reduce warming in summer to keep temps down for my trout. Just adding another reason to have a deep pond.

Nice to see you back on a regular basis!

Pond Depth. I will expand on Bob's "fish production mostly occurs in the top 4' of water. Fish production in a pond or lake is dependant on the light penetration depth. Fish production down to 4' is very true if the water is fertile or fertilized and light visibility is approx 18" to 2'. But if the water is not very fertile & the water is clear then the general rule will be: fish production zone will be down to the lower limit of rooted weed growth; sometimes 8' to 16' deep; but usu. 6'-10' is the most common range for clearish lakes. This depth of (fish) production is called the LITTORAL ZONE.

Pond Depth & Mixing. Many people "up North" including most pond builders think it takes a "deep pond" to make the water mix or circulate. They think the deeper the pond is the better it circulates. No way! Pond water does not turn or mix deep (8-20') into the depths during summer. It also does not mix very deep under the ice in winter. A pond designer once told me "ponds don't turn in summer; there's no crank on them". He was mostly correct.

Ponds do turn, or roll, or mix top to bottom twice a year. Once in the spring and once in the fall. This primarily occurs when the water is around 39-40 deg F. Or, when surface water temp is close to bottom temp. When the water is uniform temp. top to bottom there is very little resistance to mixing and wind can push & pile water on the downwind bank and it is then forced downward along the bottom. If the water is cooler along the bottom the water will push down until it meets the thermal cold resistance and then push laterally or horizontally along the top of the cold water.
The degree of temperature difference between the surface and bottom waters and the wave height determines how deep the pond water will mix.

Another depth consideration. It's hard to find a body of water that is "too deep" at the end of a drought.

I second Dave's thought. I inherited an 8 acre pond in central texas that is close to 40 feet deep in spots. The pond is fed by runoff rain and a spring, but awhile back during a year long drought the spring stopped flowing and we had no runoff rain. The water level dropped a good 8-10 feet so the depth of the lake was crucial and my fish stayed in good condition despite the situation. To my knowledge I have never had any negative effects of this lake being so deep. I always want more water than not enough.

You Texans make good points for depth esp in drought conditions and if the pond is a "leaker". Up here in the north, a well sealed pond even in "our drought conditions" only goes down 2 ft maximum. Anymore than 2ft lower and it is either a water table pond or a "leaker". See how conditions vary greatly in various parts of the country.. As I always say, "It All Depends".
Michigan Sport Fishing Ponds Book recommends northern ponds be at least 15' deep and 18-20 ft is distinctly better primarily to minimize winterkill under extended, heavy snow cover. . They currently think that depths greater than 25' provide little benefit for pond situations.

Thanks everyone...As always everyone is more than helpful in answering questions. I hope to be doing some pond contruction soon and am cramming all of the pond contruction knowledge that my little brain can handle as fast as possible. I was
reading the USGA Handbook 590 this weekend "Ponds-Planning, Design, Contruction" and after a very short amount of time began to get lost in the algebra and especially the terminology used. I'm going to read more tonight; maybe I will retain more this time.

Those of you in the north country -- don't forget that deeper means less likelihood of winterkill.

Guys:

My newly inherited pond ranges from 4.5 to 8.5 deep. It is spring fed and even during this summer's drought, it went down about 6-7 inches. I live in Erie, Pa. I have read past articles that a pond deeper than 9 feet is generally unnecessary, but....... everyone seems to have differing opinions. It currently holds a bass and bluegill population, which I have to check out next spring as to whether it needs thinned out or not.

At any rate, do I need to dredge my pond deeper?

Mark C. Keep in mind that just because a pond has cold water in the deeper zone during summer does not mean that it is spring fed. Being from PA, I will assume you know the difference in the two pond types. A spring fed pond w/ decent inflow often has out flow/seepage year round.

NOTE: The 8 to 9 ft max depth applies primarily to ponds that do NOT get snow cover for extended periods.

A spring fed pond (depending on flow in gpm) does not normally behave like nonspring fed ponds. Being spring fed, it should not form thick ice across the entire surface in winter. Areas near the spring inflow often remain ice free. If ice forms across the entire surface then spring inflow is minimal. Spring water inflow reduces the water retention time in the pond which results in flushing and good water turnover. Any thermal stratification (warm layer overlying a cold deeper layer) that develops will not be strong. Weak or no stratification is good and minimizes many typical pond problems such as summer fish kills and development of thick black, smelly sludge sediments.

Your depth is adequate if you have good spring inflow and no fish kills. Depth deeper than 8 ft are needed for reasons described above; primarily extra dissolved oxygen during winter & snow cover and water volume during low water periods.
More questions?? Sometimes I get too technical for new pond owners wrongfully assuming they understand all my jargon.

Thanks for the reply, Bill. And so far, you haven't talked over my head.

I tend to believe that my spring fed pond is minimally fed, as you suggest. It did not flow out of it's overflow tube 24/7 this past summer and went down about 6-7 inchecs in depth during our drought. I also doubt I will find it bubbling through any ice formation either. It's an old pond which I'm sure has slowed down any spring feeding action. But, I'm just going by what the original landowner told me about the pond when he built it. A sucker born every minute.

At any rate, it does have black muck for a bottom so I can't say it is flushing itself out either. The pond is L-shaped and is 1.71 surface acres in size. I have no power neraby to run an electric aerator. So, I am hoping for the best. Does that Bio Clean stuff work to clean up the muck or is this a natural result of an old pond with years of wear and tear? I don't want the pond filling up any further over time and need some advice to avoid dredging.

And, given the added info you now know, do you think I have to dredge my pond right now with its depths of 4.5 to 8.5 feet? Thanks. Bill, and to anyone else who would care to respond.

Three years ago I had my local CountyAgent, County Extension Ser.,and Auburn Unvi. out on my pond site ALL said the same thing to build a pond with a Max. Depth of 7-9 feet with a constant level of 5 1/2-6 1/2'. And thats mainly for good fish production. My pond has a levee NOT a overflow pipe and it is designed to crest at 9'-2" and it's only done it once in a hurricane after 11"of rain fell in 6 hours.

I build about 20 ponds and lakes a year .I look at alot of factors before I set the depth of a pond.1 try to factor in the amount of runoff erosion that will enter the pond.2who will be using the site and is there going to be alot of kids or young adults using the site.3factor in the amount of trees that will be shedding there leaves each year.4how much water is going in and out of your site.5If there is and area that can be used to get more detph and not damage the hard pan and still leave enough shallows for good fish spawning.I recomend to the ones with young adults or kids to only go to a 12' max depth that is about as far as I can dive down to pull somebody back to the surface in case of an acc.If it starts at this depth it should stay at least 10'deep for many years.And that is the recomended depth to substain healthy fish for the top two thirds of the USA hope this gives you some things to help. DOC