Basins
Basins
Storage and streamflow rolled up by western river basin.
Updated Jun 18, 2026
American-Sacramento basin
Reservoir storage across California
Colorado (Lower) basin
Reservoir storage across Arizona / California / Nevada / Arizona
Colorado (Upper) basin
Reservoir storage across Arizona / Utah
Flathead-Columbia basin
Reservoir storage across Montana
Green-Colorado basin
Reservoir storage across Utah / Wyoming / Wyoming
Gunnison-Colorado basin
Reservoir storage across Colorado
Missouri basin
Reservoir storage across Montana
Rio Grande basin
Reservoir storage across New Mexico
Sacramento basin
Reservoir storage across California
San Joaquin basin
Reservoir storage across California
San Juan-Colorado basin
Reservoir storage across New Mexico / Colorado
Trinity-Klamath basin
Reservoir storage across California
Wind-Bighorn-Missouri basin
Reservoir storage across Wyoming