I may have stumbled on a way to fix some types of leaks.
I have a small pond, which was dug in early September. It is only 20 by 20 feet and about 5 feet deep. It is built into a slope and has a dam. As soon as it was dug the water gradually came up about 2 1/2 feet from 2 very small springs. One was above where the water level reached before it stopped coming up. Then we got about 6 inches of rain and it came up a foot. It has been unusually dry here and over the next week with no rain it lost about 6 inches, and then stayed the same level for a couple days.
I was worried about this as the back slope of the pond is visibly seeping water and dripping into the pond so between that and springs it seemed a lot of water was going somewhere.
When the pond was excavated the clay in the dam was not compacted as well as it could have been as it was on the wet side, and difficult to work.
When the water stopped going down and found a level it was maintaining, I went out with a wooden baseball bat and worked my way along the inner sides of the pond, beating it down with the bat as I went. I found if I dipped it in the water I could get a couple good thwacks with the bat before clay began to stick to the bat and I had to dip it again. Every time I hit, the clay would indent a couple or four inches and I just kept working it, thwack, thwack, thwack, dip, thwack, thwack, thwack, dip, until it was at a degree of compaction that the bat only made one inch indentations and the clay began to feel solid and plastic. I did this right down to the water line and even an inch or two beneath. Then I used a shovel in the same way, smoothing out the furrows left by the bat, dip, thwack, thwack, dip, thwack, thwack, all along the sides.
The water immediately started rising and in the two rainless days that followed the pond came up 2 inches. We have had some rain now and it's come up more but it doesn't seem to be loosing what it gains.
I'm not sure if this could make the problem worse in some situations, but it seems to have worked for me. If someone has a leaky pond this might be something to try as the simplest solution.
