Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? My Pond, my problem?

Hello, folks. First-timer here. After reading extensively through the forums, I find myself now educated and ...confused! I thought maybe I'd post a few pix and give some info on my pond.
First, I did not build this pond, rather it came as-is with the purchase of the farm(ette). As of today, it is approximately 7' deep at center, and since 10/2011 has been no less than 5'-6' deep at center, even through last summer's drought. It is stocked with Black Crappie, and I'm told also catfish, although I have no proof of the cats. The pond *should* hold enough water to be around 15-20' deep at center.
I live in Missouri, a bit south of the Lake of the Ozarks.
My elevation above sea level (which may not mean anything) is 1028ft.
Our well was dug 370', pump depth 260', water level 160'.
I have seen this pond hold about 10' more water following days of rain, and then lose it over the course of a dry couple of weeks, but never fall below 5-6' at center, just a bit less than the pix currently show.
The pier I just tore down (after I fell through it) in the last couple of days. It was improperly built, in my opinion, and had rotted out in several spots since being built five years prior. I will be rebuilding it. I'd appreciate any thoughts or theories on what my pond's problem might be, and how to go about fixing it. Thanks! (Big thanks to Belly the bulldog for providing scale)
Picture 1
Picture 2
Picture 3
Picture 4
Picture 5

Welcome to the forum!
Beautiful setting, nice mix of thick trees behind the dam, and a more open setting on the left side of the pier.

The placement of the pier leads me to believe the lake was once full...
I can't really say much on what might be the problem. I'm sure some of the experts on the forum will chime in soon.

Looks like you got a great fishing hole there. The closeup photo of the sedimentary type you have in "Picture 5" depict that you have a very porous soil type. This may be the reason why you lost water from 10' to 5' or 6'. The water at the bottom retained because you have a high build up of fine sedimentary layers, over time, at the bottom, OR, you have a nice layer of clay which capped the water from leaching through the bottom. You may want to think ahead as well in incorporating an outlet when the pond gets filled up after the pond's renovation. We can't have your pond becomes flooded. It appears that your area tend to receive quite a bit of downpour, or rather, your pond receives quite a bit of run-on of rain water in a few days. A large diameter outlet is definitely recommended.

You may have to scour and compact your pond, and pack it down with clay. We have great experts pond owners and builders here that will give you awesome insights.

Thanks, Nate. We love it here. As far as the pond, I hear around that it never held water. The house was built recently (1998) and the wood that the pier *was* built from is stamped 2007. I've no idea when the pond was constructed itself, but I'm sure that over the years it has filled & leaked out several times.

Appreciate the input, Leo. Although not visible, on the far edge of the pond, left of the dike, there are 4 pieces of 6'x6" corrugated plastic piping to serve as an outlet for overflow. I have access to a skid steer and have considered using bentonite and tilling it into the exposed areas of the pond "wall" and then compacting it, but want to make sure that I'm barking up the right tree first...

You are barking up the right tree. But there are multiple trees you may need to bark upon

I think this may not be an intentional pond at one time, based on the topo layout from the panorama shots. However, someone went in, and expanded the ponding area into a uniform designed pond, without thinking too much on the soil type and what required to be done. 4 of the 6" pipes, rather than a single large outlet is a sign of an improvised increment drainage system, rather than a calculated/thought-out design. The second is the poorly built pier, or rather, rotted pier, which is a sign of ill-maintained. But the fun thing is when you dig up the supporting legs will tell you whether or not the pond was constructed on the whim, based on how deep the supporting structure is buried, and if concreted footing was also poured..You have quite a bit of work on your hands ahead.

The pilings (six of them, now 2 standing) were not cemented whatsoever. There is no evidence of any sort of footing, and they were buried about one foot (!!!???!!!) deep. Once I knocked down the support beams of the pier, I was rather easily able to push the pilings over by hand.

So..you have plenty of work ahead of you LOL

Were the pads of the posts below frost zone, if you even have such a thing where you live? Lots of folks on the forum here will just use water pressure to drill a hole down for the post and drop it in. Depends on you, and what you want I guess. In my area, you have to worry about them in the opposite direction (getting heaved up by ice).

Frost zone. Hadn't thought of that. Hmm. Doing a quick search, looks like I need to go down about 14-20 inches for where we are. My intent was to drill down two feet to re-set the pilings, so I ought to be okay. Frost Zone Depth Map

That depth would be from the water level down. So you may not need to worry at all about it. That was why I was thinking the previous owner wasn't worried about the depth into the ground, or that good of a footer.

More reading = more questions.

So, I now know my pond's size, .07 acres, and eventual size .25 acres once full.
I know my budget size (not so big!).
I've got the fever andI want to get this ball rolling.
Where should I begin? Pulling weeds? Baby trees? Can I burn them out?
Then what? Bentonite, Clay, DB-whatever#? What works best for the money?
What about the soil conditions seen in the pictures? What have I got here? Is it suitable, or am I in for some rude truth?

Finally, thanks to all who have answered so far... and... sorry I didn't put this thread in the new member forum, which... I didn't read until after the fact. Duh.

You did good. New member forum is to introduce yourself, then posting in the appropriate forum to get the most visibility for that particular problem. You got it right without trying!

I haven't seen any successful, long term results, (i.e. longer than a few years) of anyone on here that has used bentonite or another sealing product other than properly compacted layers of clay. If someone knows of a pond where those products have worked longer than a few years, please chime in - I'd like to hear about it.

For more "hands on" free information, stop at your county's NRCS office. They can give you information on soil type, calculate your watershed to properly size the overflow pipe, etc.

I have yet to see bentonite lasting more than 4 years, UNLESS, there are run-on that introduce extreme fine sediment in a thick layer more than 24 inches to create a secondary sealing layer at the bottom. Aside from the bentonite, thick pond liner (the landfill material grade) lasts more than 15 years, and still going strong.

I only see clay as a viable solution for long term scenario.

As for the pilings, you might as well start out with that first. Calculate way ahead of time how high the water should be, and provide yourself a nice 2' to 3' above the tallest water line if feasible. Pilings, for safety purposes in the long run, should be at minimal of 36". Recommended depth is 60". Of course, I'm thinking in a generic civil engineer mindset, when it comes to general safety reasons.

Burning the plants? NO!! You're leaving root systems in place where the roots will provide leaching pathways later. Scour the soil to the depth of the plants' roots depths, and recompact with clay when possible.

Rude awakening..yep..plenty thereof later. Try to have the proper drainage system in place before compacting the clay into the soil. This way, you have the clay mixture to seal in the drainage pipe, preventing seepage, and possible blowout because of weak soil compaction. I love seeing cascade blowout during heavy raining period because consultants and contractors around here are so lazy in doing the right thing, and try to save a buck or two.

SLS- Do I see some kind of plastic/rubber near the shoreline that may have been a liner at one time?

In a pond your size do not forget about the option of a liner, epdm or otherwise