I found a bullfrog floating in my pond. Its been snowing and sleeting past few days and its still alive.?

I was breaking the ice in the pond for the stray cats to be able to drink. And found a bullfrog full grown floating with the ice. I beleive it was lodge in the plants at the bottem of the pond. Found it 5 hours ago and now it's waking up from hybernation. I found out they do hybernate underwater, Should I still let it lose in a river? Will it be to cold for it to have time to look for a place thats its safe in? I can take care of it until winter is over, But really prefer not to. It's half way awake, Can I keep it in a container at the prefered temp for it to go back to hybernation and it will be fine when spring comes around,