High in the Rocky Mountains, under thin air and bluebird skies, the Colorado River basin is slowly filling its savings account. Craggy peaks become smooth walls of white and piles of snow climb conifer trunks, covering even the deepest, darkest corners of the woods with a glimmering blanket.

The snow that accumulates in the mountains of Colorado and Wyoming will eventually become water in the Colorado River. Some of it will flow as far south as Mexico, running through kitchen faucets in cities and suburbs along the way, or watering crops that keep America fed through the winter.