Thanks for all the good info! You all have been very helpful.

I have selected a site for my 1/2 acre pond in central Kansas and dug some test holes. My question is how far down should I go to get water. I want the deepest part of my pond at least 15 ft deep. At about that depth I hit really wet clay, 3 ft deeper and I hit rock. Should I bust through the rock to see if I can get some water or stop at the clay? FYI I know that I will have to support the pond with well water and do not expect it to be supported by a spring, however it would be nice to have some free water to keep it clean.
Thanks!