I lent him a stick to grab onto and pulled him out.
I guess it was too thick for his claw because he got stuck.
When I finally got him free, I flailed and failed to pick him up by the tail to put him back in the water because I guess I'm not a true farm girl yet. I had to use cardboard.
Oh, well. I'll have another chance some other day, I'm sure. His home is just beyond the back door!