Last year I was witness to two close calls. Three guys tried to cross a series of rapids and fell into the river in December,1 guy was over his waders for over 15 minutes before two of my friends could reach him and get him to shallow water. All three were wet and it was pouring rain but their car was less than a 1,000 metres away.
The second event was the following week in December and two kayakers, a father and son tried to run the rapids. The father made it and kept going but the son's kayak rolled and he was dumped into an eddy. Two other friends pulled the kid out, in the process they both lost their rods and reels. We got the kid into one of our buddies cabin with a wood stove. This kid was totally blue and would have been in real trouble if not for the cabin. They were not close to their take out point and it is over 5 miles from the fishing spot to the nearest village.
Both of these groups were not familiar with the river, and certainly were not aware of the conditions. In over 25 years of fishing I have fallen in my share. Usually right after I say it never could happen to me. However when fishing in December I always have sapre change of clothes, a tight wader belt and a preference not to dance in fast currents and fridgid waters.