I once said to a young man at a viewpoint west of Idaho's Sawtooth Range, "A lot of water runs out of these mountains." "This part of Idaho is a granite batholith," he replied without hesitation. I appreciated the information, and was inspired by his enthusiasm.

Granite landforms efficiently store precipitation, and play it out evenly throughout the year. This can make it seem like more water runs out of granite mountain ranges than could possibly fall on them as rain and snow. And it’s true, a lot of water runs out of Idaho’s granite mountain ranges. Rivers like the Payette and Salmon are raging torrents of whitewater.