Mountain watersheds provide 60 to 90% of water resources worldwide, but there is still much that scientists don’t know about the physical processes and interactions that affect hydrology in these ecosystems. The Surface Atmosphere Integrated Field Laboratory (SAIL), led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab), is an unprecedented climate observatory located in the Upper Colorado River Basin. This collaborative research effort is an ambitious campaign to collect a vast array of measurements that will allow scientists to better understand the future of water in the West.