With an underwhelming snowpack right now, the U.S. Bureau of Reclamation’s initial 2018 forecast (pdf here) projects combined storage in Lake Mead and Lake Powell, the two primary reservoirs on the Colorado River, will drop to 21.7 million acre feet by the end of 2018. That would be the lowest Mead/Powell combined year end storage since Powell was first filled in the 1960s.
WARNING: Just this afternoon, I was discussing reservoir storage data with some folks working on Colorado River policy analysis and I strongly discouraged using the 2018 forecast yet. It’s early. It could snow a lot. It also could not snow a lot. The error bars on a forecast made in January are huge, it will almost certainly change in one direction or the other. But for what it’s worth, here’s my updated combined storage graph with the 2018 forecast added.
There’s still enough water in storage to prevent a 2019 Lower Basin shortage declaration. But the risk for 2020 is rising.