Winter/Blizzard effects on river defense

[deterrumeversor]

Can anyone tell me please, in 3.3 do rivers "freeze over" in winter or blizzard turns? I could not actually find this in the book. It covers most other aspects of the blizzard turns except that. This is of paramount importance to me right now. Since I am facing a strong Soviet offensive in a '43 campaign; it is winter now and most of my line is based on river defense. I need to know if this will hold up in the dec., jan., feb. months.

[Denniss]

AFAIR rivers/swamps are counted to be frozen over at least in blizzard, probably even in standard winter conditions.