I too am in a bit of a dilemma about how to use my wort chiller this winter. I'm in PA, so not as bad as WI, but it does get below freezing and we had some 28' of snow last year. I really do not have a good way to let the output of the chiller go without turning my driveway in to an ice rink. It's about 110' long and on a steep angle so not to mess with.
I will probably go back to what I did pre-wort chiller. Put the kettle in the laundry room sink, add ice and water, and start to stir when it gets below 90F to avoid hot-side aeration. Takes 45-60 minutes as opposed to 20, but gets the job done.