How to clean roof moss

I have a country home in Courtenay BC on Vancouver Island...read "Rain Rain Rain Forest". This last Nov and Jan seemed like perma rain, certainly worse than I remember and I have lived in BC since 1980. To make a long story longer, I noticed a rampant growth of heavy lumpy moss on my roof, driveway stones, and walkways, and I set out to find how to get rid of it. As we are on a fish bearing river, I felt very strongly about using any chemicals that could negatively impact the river or the ground water that might affect our a well system. I'll continue telling about my findings later in case anyone else has the same problem.