Pond Boss Forums INTRO Questions & Observations New pond level drop - should I be concerned?

We built a pond a year ago and due the drought it never got more than 2 feet of water in it before completely drying up. I had posted previously that when building the pond last year in the main basin they broke through the clay and a spring started seeping in. The forum advised that this was not a good thing so the contractor went back in and put 2 tons of betonite clay and additional clay over the spring. This summer it did dry up completely and there were giant cracks at the bottom of the pond. Over the past few weeks we have been delighted that we had 7-8 inches of rain. There are 2 ponds upstream of this larger one and they are near full now, so the next rain should send a lot of runoff to this larger pond.
The first 6 inches brought this new pond to a new high level, but receded about 2 inches within the next few days. After another 2 inches of rain, the pond came up a bit, but it is still below the highest level achieved following that big 6 inch rain a few weeks ago. It is stable now. My concern is that it may be leaking, so I called the contractor.
He told me that we have had such a small amount of rain over the past year that the ground in the area, including the clay at the dam, was acting as a giant sponge and was going to continue to wick up the water until the ground is saturated. This seems logical to me. Sound right to the forum? It just seemed odd that I have less volume of water at 8 inches of rain then when I had 6 inches! When this pond is full the entire valley should flood all the way back to the white house in the background and encompass about a 3 acre area. That's the plan, hopefully some day that will actually happen!

Sad to see, but glad there's water staying put now!

Oh, and you're pond's on fire!

A little off subject, but what is that hole at water level of the 2nd picture?

That is a place where the sides are collapsing into the water as it fills. My assumption is it is from runoff above creating a cave. If you look down the shore you see several smaller ones. The sides are all good clay with about 2-3 feet of sand above it.

Until proven otherwise, that's what I think.

Here in Oklahoma, we have a caught different rains that have been very been benefical. Although it appears wet on the surface after you digs down about 4 or 5 inches and the soil is totally dry. The truth is the soil is completely parched and probably soaking up all the water it can.

UPDATE: After the spring record rains flooded this entire ravine and got this pond within a couple feet of being full, we have been losing 2" per day and have lost over 3.5 feet over the past month or so. This is the case even with a small amount of spring activity putting a bit of water in each day from upstream. It is not leaking behind the dam - no wet spots anywhere. This is a damned up ravine and while I think the belief that absorption was the initial culprit costing us 1/2 inch per day when it was lower - with a consistent 2" per day drop we definitely have a bigger leak problem than that. Needless to say, after my elation with the pond filling it has quickly turned to disappointment.
With no leak on the back of the dam I assume that the leak is coming from the bottom of the basin where he did the betonite slurry fix and we are losing the water going under the dam or someplace upstream we are piping water under the clay and then under the dam. With no visible leaks on the back of the dam, the contractor says at this point there is little to do but wait and see if the pond stops leaking at a certain level and determine if there is a problem at that elevation where the leak slowed. Of course if pressure if forcing the water through the bottom, a lower pond level could slow that only to return when the water level comes up again. Any suggestions on how to determine where the problem lies?

I feel your pain. I have no suggestions on how to find the leak.

What's the contractors plan of attack if the pond does stop dropping?

After re-reading your first post, it seems that there is sand above the clay that is at the bottom portion of the pond, correct? Was the sand covered up with clay? If so, how was the clay compacted?

When the contractor broke thru the clay at the bottom of the pond to the Spring, and he re-filled with clay, how did he compact that clay that he replaced?

Contractor plan is to wait and see if the leak slows at a certain elevation and carefully check out that area. There is some speculation that it could be where a large 40" diameter tree stump was removed that could have potentially created a pipe into the water table.
The original site before excavation had 1-3 feet of sand over the ravine. At the dam site he pushed the sand to the back of the dam area until it was all clay at the bottom of the main basin. He cut a 4-5 foot trench at the center of the dam site into solid clay and then pushed and compacted a clay core. Using the bulldozers he cut roughly 10-12 feet down into the clay bottom 5-6 inches at a time and pushed it to create the dam - it was all good clay. The second photo taken from the top of the dam shows how the basin was cut completely out of a clay bank - you can see the clay depth at the sides. After the dam was near finished I noticed some seeping at the lowest part of the excavation in the main basin. I believe he reached a lower spring. I posted to this site and was encouraged to have that addressed and repaired. In the second photo you can also see the seeping at the center of the photo to the left and right of the trench. Following a small rain combined with the seeping springs eventually the basin had about a 12 foot diameter puddle that was 10 inches deep. Contractor added 3 tons of betonite clay and had a circulating pump mix it to the consistency of pancake mix. He pushed another foot or so of clay over it - but could not compact it due to the high moisture content. He believed that that quantity of betonite should be more than enough. When that area had 6-7 feet of water over it we were losing 1/2 inch per day which we attributed to wicking from the dry soil conditions. When the pond level came up another 6 feet or so and flooded the upper ravine the leaking increased to 2" per day.
The pond has now dropped to the area where ther is a sinkhole from that large stump - hopefully we see a dramatic improvement in water loss below that elevation which could indicate we found the problem. Contractor continues to doubt the leak is in the main basin. Any other suggestions on what to look for would be appreciated. I am sick that I lost all that runoff from the fantastic 12 inches of rain we had earlier in the year.

I hope you find it! It looks like he compacted the pond with the dozer tracks?

Yes, with a D8.

I wanted to give an update on the progress with this project since the last post. We drained the pond this February and the contractor returned to remedy what we believed to be the source of the leaks. Concensus was that their were two factors - that he cut too far down through the clay in the main pond basin opening up a spring that became a drain as the weight of the water increased and secondly that the pond had too much sand on top of the clay around the sides of the pond wicking water and increasing evaporation. The contractor removed two 18 wheelers of sand from the sides of the pond exposing the clay foundation. (I gave him this sand to help offset his expenses with the repair.) He then re-profiled the basin making the sides less steep and therefore also wider. He put 3 feet of clay on the bottom of the basin near the dam, where we suspected the spring problem. He also added an additional 8-10 inches of clay upstream to the basin. Here are a few before and after photos.
Pond after draining. I had stocked about 50 large male bluegill a year earlier and a handful of females. I was able to net every large bluegill and put in other ponds. They had grown much larger!

In this photo you can see the large amount of sand on the sides. Some of this washed in over the past few years.

After they finished they spread a small amount of sand back on the sides so I could get grass established again. This is what it looks like following about 6 inches of rain that we have had since completed. I noted that this past week we had 1.25 inches of rainfall and the pond increased by 1/4 inch. Meaning we lost a net 1 inch in the past week - I imagine from evaporation or wicking. So far so good. Our area never did get enough rain this spring for the ponds above this ravine to overflow. When that happens this pond hopefully will fill rapidly. If I can maintain this level or close to it all summer, I hope that fall rains help finally fill the pond.