Welcome to the site. I live in Grayson County, near Gordonville, and have had quite a bit of experience with leaking soils.
If you lose an inch in a week, that's not bad. But, with as much rain as we have had this fall and winter, all the absorption should have already occurred. If you lose an inch each week, you should have enough rainfall to keep your pond close to full most of the year. Considering what you have said, I would bet you are losing that inch to seepage.


Teach a man to grow fish...
He can teach to catch fish...