Sounds wild that this much snow would add this much weight to literally push the water right out and possibly crush the koi???? If there is several feet of snow on top of the mudpond, the snow towards the botom would turn hard and eventually form into ice....Thats what I see when we have heavy snows which sticks around for a while.....Just never saw this happen to a pond....Learned something new....I think, it could be disinformation though?
Never saw it here in the land of frozen lakes, but then again I have never seen a Japanese Mudpond...Let alone one during winter....Wild winter extremes for sure for the Japanese breeder.