Pond Boss Forums POND CONSTRUCTION Creating habitat Stability of Structure Cut Into the Clay Bottom

I am still planning my ponds (yet never excavating, sigh!).

I have a question about creating structure where the pond bottom is made of cohesive clay. I have seen bottom contours with steep clay shelfs incorporated as part of the design.

For example, see this image of a clay shelf with FHM spawning structures.



However, I also see many ponds constructed with an absolutely clean "dish pan" configuration.

I would prefer some structures in the clay. (It is also more efficient to doze the material in slots, rather than create a uniformly clean bottom.)

However, I DO NOT know the reason for the uniformly clean bottoms - and when I don't know the reasoning behind a standard practice it worries me that my idea is stupid!

I can see how a pond with constantly changing water levels would quickly erode away the clay shelves every time the wave action was at that level. This would rapidly redistribute the clay to fill in the deep spots of your pond that you just paid good money to excavate!

How about the survival of clay features in ponds that maintain constant water levels?

Can I get some advice from the Pond Boss crew that have been able to monitor their bottom structure contours over time?

Thanks,
FishinRod

I have an underwater Island in one pond, with approximately 45 degree slopes, that has one end of a dock anchored on it. One of the two posts has settled about an inch in 14 years; that is all the instability I have noticed.

Thanks, Theo.

Have you ever drawn down your water level for maintenance, etc.? If so, how does the slope of the sides of your underwater island compare to its original state 14 years ago?

A 1:1 slope (45 degree) in clay should be too steep to be stable as a bank feature subject to wave action. What is the depth of the "top" of your island?

Your feature is exactly the type of thing I am asking about. Are clay structures below 6', or X depth stable?

Full pool depth of the island is 3'. I haven't ever drawn it down; when the water is lowest/clearest the area looks the same as it originally was. Pond is 1/2 acre with tall trees West (prevailing wind) of it, so wave action is very minimal.

Wow! Even in a protected pond, your water has to have been slapped around by storms a few times over a 14 year period.

Good survival at only 3' down is certainly promising. Thanks for the data point, Theo.

FWIW the top of the island (dubbed "Devil Dog Island" by my wife, after our old Corgi) is about 25' across.

The more stable the ground, the better it is at holding it's shape under water. The dish pan ponds you talk about are most likely ponds that needed to be rolled and compacted for them to hold water. Can't pack a vertical surface.......

Either way the pond is constructed, fish like to congregate around changes in the bottom of the pond. BUT I would not recommend contouring the bottom of the pond in place of adding cover for the fish to utilize.

My plan was to create some clay-cut structure on the bottom to be enhanced by adding man-made cover before water fill-up.

For example, leaving the last dozer slot or the lowest clay pit created by the excavator. I was going to create the final contour such that these spots would have circulation and not become stagnant bottom water. (I think my bottom will terminate in dense blue clay, so I will NOT have to compact the bottom.)

The clay in my test holes is very sticky in the bucket. I believe it is cohesive enough that it would initially be stable in the underwater environment. I was just worried about the long term!

Yes you can do that effectivly (depending on bottom soil). See Ray Scott (Bassmaster founder) method. A very good complete concept.





https://forums.pondboss.com/ubbthreads.php?ubb=download&Number=12844&filename=RayScott.jpg

Thanks, ewest.

I have previously seen that exact drawing.

The "concept" is awesome. I was hoping some of pondmeisters here had tried it, and observed if the results had lasted 1 year or 10 years?

I have seen lots of great ideas fail after they were subjected to the "proof of concept" test. And I certainly lack the personal knowledge to evaluate this idea based on my own experience!