Don't panic yet Joe. You may have better clay deeper. Some of those maps are not 100 percent accurate. You could have pockets of soil like that etc. and not the entire area. This could be remedied by moving good clay where it is needed. I wouldn't hasten judgement until you get your test dig made.

If it makes you feel any better I was discouraged to build my first pond based on the test dig. It was great clay down to 13 feet and then it was sandbox sand and then large gravel. The most beautiful sand and gravel you had ever seen! Great for a gravel pit but horrible for a pond. However I had the excavator go down only 11 feet and pack a layer of clay and this pond has not given me a lick of trouble since the 9 years it's been there. In fact it has performed better than the other three ponds on the property.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.