Its hard to look forward to a river trip when the pre-trip preparation involves shoveling snow off the raft. Without sticking so much as a toe in the water, you begin to make assumptions about its temperature. However, when you have customers foolish enough to sign up for a trip during such weather you find yourself shoveling snow off of a raft. Also, at the beginning of the season a checkout trip is required. Even if you know a section of river well, there are many hazards that can appear in a river between rafting seasons. Threats like: trees could have fallen across sections of the river, the river might have had sections "restored", rocks could have fallen from cliffs and created new rapids, the landowners in the canyon might have built new dams (or installed machine gun nests), etc.