This is horrible.
I remember sitting in a tube on the Pedernales one hot summer day, and the water was a little up but not dangerous, yeah, right. I got flipped over in a little rapid and pulled under for a ways - couldn't get out. Terrifying. Then I shot out of the water and was fine. Water was probably no more than 3 or 4 feet deep. I'll never forget how strong that current was, holding me under.