Colorado River reservoirs

The ocean store did not shrink by the volume of Lake Mead. The local store did. Powell and Mead are managed reservoirs on a river whose compact was signed in a wetter early twentieth century. A bathtub ring is the last high shoreline as a stain.

The water-cycle lab’s abstraction slider is this. A closed global cycle still allows a basin to be in deficit. Snowpack in the Rockies is the headwater store. A drier hydroclimate plus upstream use plus evaporation from open reservoirs is the budget.

Students should not say ‘the Colorado is running out of water on Earth.’ They should say ‘the allocated flow exceeds the river that is actually there in a dry decade.’