Probably won't help much but when we floated from Sand Island to Mexican Hat in the middle of January, it was totally clear of ice and quite warm on the banks. I would think that now with longer days and it has been relatively mild down there that you would be OK, but ? The ranger at the put-in was very helpful and should be on duty Wed-Sun. He did mention however that if it does freeze over on the lower section, it is usually at or below Government Rapid. Hope you have a nice float!