Hope your fish come through O.K. too. Here too we have had heavy snow on and off with several thaws. That said I relgiously clear strips of snow off with my snowblower to stay on the safe side. I used to use a diffuser in the shallow end of my ponds but seemed to have better luck clearing off snow to let light in.
I usually make some holes around my cages and clear snow around them to let light in also.
Bill Cody is a good one to gleen informaton from about this topic. I believe he has it down to a science on how many days of snow cover until you should worry, how many inches of snow etc.
Here'a pic of what I do on my small pond immediately after a snow fall. I would also do it on my big pond but there are no fish in it at the present so no need to do anything.
