Well, only the small pond sat for an extended period of time with water in it.
However, that was before I got it to full depth.
The basin was 8 ft deep, after winter it had pretty darn near 8 ft of water in it.
It sat in hot dry weather for 2 months before I pumped it out to finish the excavation.
From the ice melt in April, to early June, you could see the water wicking into the banks. I lost maybe 1 inch per week of water level.
This large pond, I will be pumping out soon. So I will not get a good indication of that for both ponds until next spring/summer. As I will be pumping out the large pond into the small pond and letting the excess run through my overflow system, then finish the large pond.
I do have a lot of clay, and am still wondering if I should be lining the banks of these ponds to ensure the water level does not fall drastically. So far I have not see any drastic water loss, but none of the ponds has sat a whole year without me pumping them out, etc...
