River ice is never safe and I don't trust it, unless you live in an area that has long periods of deep freeze. Also it's hard to find rivers that have ice which is smooth enough to skate on. The river in my city would be impossible to skate on because the ice is so rough and uneven, due to the movement of water and freeze/thaw cycle there are huge big chunks of ice blocks the size of a huge boulder all over the surface of the river...It's safer to ride a bicycle with studded tires, then it is to take chances skating across frozen river.