What type of legal action can I take against my 5 yr olds summer program after they left her at the pool?

She was found safe so i find it unlikely there is anything you have to sue them about. I understand your anger and i would have been no different. I think the best you could hope for is to file a complaint with Health and Welfare and maybe they can have them put on warning or require they have a suitable number of people to watch these children. I suspect the lady who said she had to many to watch was probably correct. But also please realize mistakes are like accidents which often happen out of our control so lets see if the out fit can be made to be more responsible so as there is a much less chance of a mistake or accident.