The Southwest is bone dry. Now, a key water source is at risk.

California and six other Western states have less than 60 days to pull off a seemingly impossible feat: Cut a multi-way deal to dramatically reduce their consumption of water from the dangerously low Colorado River.

If they don’t, the federal government will do it for them.

A federal Bureau of Reclamation ultimatum last month, prompted by an extreme climate-change-induced drop in water levels at the nation’s largest reservoirs, reopens years of complicated agreements and political feuds among the communities whose livelihoods depend on the river. The deadline represents a crucial...