How fabulous to see Sebastopol geese, and blues at that! We have a flock of Sebastopols, mostly lavenders and blues, they free range our farm all year. We are, of course, a lot warmer than you in the winter, but I will give you what advice I can. I would assume you will have a shelter that is water tight and warm. They do not need water to bathe or swim in, we have had great success using a horse automatic waterer. The one with the bowl. It will get dirty but since it only holds a small amount of water is easy to dump and clean. I then dilut the spent water and use it on plants.
They really need dry bedding since their feathers don't have a spine. It inhibits their ability to hold warmth and in your climate that would be a must. We feed whole corn and lay pellets to our combined birds. Since there is no egg laying going on, we don't worry about supplements. There have been many times during our horrendous drought that they have had nothing green to eat and do fine. I have a couple that will eat lettuce but the majority could care less. Some of my birds will eat bread as well, we hand feed when we have company, but again not all. My guys show no interest in scratch but have cleaned up extra sheep feed or oats from troughs. I know that show birds are confined and apparently do quite well.
gonna have to come up with a formula to get them through 'til Spring.
to ATP. I have geese as well as ducks and chickens, too, but live in a much warmer zone (10) with no "real" winter.. In the past, I have allowed mine to be out foraging but my current situation forces me to keep them penned now (plus they are geriatric geese). Are your geese penned, pastured, or ? 
