I don't have children...
Chances are extremely good that she will NEVER go into any water again for the rest of her life after that treatment. I don't know what brings people to set up such a program and what brings parents to put children into that. Their own children, mind you.
Otherwise I agree with dobarton. Let your daughter throw that kid into the water herself and watch the kid cry - if shes able to do it. And if not it is just being extremely unfair to have someone else do it.
What I would do if I was in that position: Seducing. Go to the water with the girl, and don't force her into anything. Nothing at all. Don't even ask her to go in the water. Don't give any sign or idea that she should/needs/must do anything, just let her be happy and relaxed. Go in the water yourself and enjoy it. Just repeat that again and again. Chances are good that she will join sooner or later.
And if not - so what? She is a THREE YEAR OLD. Why on earth does she have to go into the water anyway? IT'S JUST A SMALL KID - let her do what she likes. The tough part of life comes early enough anyway.
Parents... and idea about what kids should... and should not.
Since this is a public forum I would of course never say that I think this is a little fanatic.
Buy Khalil Gibran's book 'The Prophet' and read the section about children to your daughter.
Never mind... I am just shocked.