ditto a couple of good points by Jas
Soils maps can be very deceptive since they only show surficial soils
I was told by more than one source that the soils maps were samples extracted in 1960's or '70's and they never went deeper than 60"...truth be known? anybody?
Dig a couple of test pits in front of and behind where the dam will go
last August, my contractor took 2 days to beat thru the woods to clear a drive to my pondsite and boy was I nervous when he started digging with the excavator for soil samples. The very first hole...4..6..8 buckets...all black and crumbly. 9 buckets, same thing, I think I'm gonna be sick. 10th bucket, he sets to the other side of the hole, gets out and grabs a handful. He rolls it into a ball in his fist and starts working a flat ribbon thru his thumb and forefinger...it gets about 3" long while I'm staring like a deer in the headlites. He looks up at my white face and says "this is good stuff". I collapsed and fell into the hole! (just kidding...I only collapsed).
