One of the leaks I found was in the dam. I seem to have fixed it by just whacking the area of the bank which was presumably above the leak with the head of an ax a few times, but I think this area needs more work. I noticed that compared to other areas of the dam it is still quite soft.
When the dam was built, the area was so moist, even at the driest time of year it was not possible to properly compact the clay. The area of the dam with the most recent problem was very soft and even mushy for the first 6 months after the dam was built. I used a large stick and a baseball bat to poke 2 foot deep holes in the above water part of the dam and then I packed these with bentonite which seemed to firm things up quite a bit. In the first summer I repeatedly poured bentonite slurry into the cracks that formed in the clay dam as it dried out. Looking at my records I see that last winter, the second year of this ponds life, after I had done this, the pond stayed full to over flowing, but this winter it has quickly dropped down to the same level it maintained through the summer. Last summer I didn't pour bentonite into the cracks that developed. They were much smaller than the ones the year before, and harder to see because of the grass cover, but I am guessing these small cracks created a weakness that provided a water channel once things got wet again, which is why the pond is going down to the level it maintained in the summer.
Next summer I will make sure I have a couple sacks of bentonite and that I repeatedly fill any cracks that develop with bentonite slurry.
The other leak is a bit more difficult as it is in the natural soil in the side of the bank, in the uphill section of the pond. This new leak is about 1 foot from the leak I previously fed small bits of acrylic wool in hopes of plugging it like I plug my drains in my house. I am thinking this new leak is probably connecting to the same underground channel as the one I tried to fix before, though the water is entering this new leak from several inches higher than the first one I plugged, and as far as water level goes what I did to fix the problem did create a substantial improvement.
I am going to wait till we have a big rain and there is a stronger current going into it and try feeding it some more bits of wool. I am not really hopeful this will be a permanent solution, but it can't hurt. Come spring and some dry weather I may dig a 2 foot deep hole or small trench in the bank which will intercept the path the water is traveling through and then pack this with clay and bentonite, and see if this provides a more permanent fix.
I would really like to be able to retain enough of the water coming into this pond so I can send the overflow downhill to automatically water my garden.
Obviously it would have been a whole lot easier to have done it right the first time....
