> While some of what that means for California remains to be seen, parts of the process have already begun, including the steady decline of the Colorado River. Lake Mead, the nation’s largest reservoir which is located along that river, is now only 150 feet from dipping below its lowest intake valve, officials announced this month.

How much time will it take for a 150-foot drop at current rates of loss? I haven't been able to find an estimate of the rate of loss in the last couple of years. I also imagine that the rate of drop could be non-linear.