as for hitting the water table or not...
There is a gravel pit going in my backyard if we renew the contractors lease the pond may be as big as 14 acres.
This pond is dug into the water table. This is a very unique situation because its being dug with a couple big payloaders, not bull dozers. Also this is a huge contractor (using the gravel for a highway) and is dewattering the pit into a local creek. The neighbors well ran dry because of the dewattering.
The expense of digging a pond like this makes it very impractical for pond builders. Also you can never drain or fill the pond. If the water table drops so does your pond, no way to top it off with a well or fix a leak. If you have gravel on your property it might be worth a try, but to dig into the water table a significant amount requires extra equipment, time and expense. And has several disadvantages.