The natural state of rainfall in the desert southwest is arid to semiarid. The engineering approach to water management can only go so far. The necessary solution is somehow to limit population in arid regions— much cheaper and environmentally more friendly than trying to build out costly canals and dams and what not just to feed more peoples’ toilets and backyard swimming pools.
Instead of wasting billions on high speed trains, the state government of CA should have invested that money in large-scale desalination plants. Las Vegas would have been one very logical customer for that production if they couldn’t find enough takers in CA.
I think the gradual drop of Lake Mead is 90% water use and 10% drought in the long-term analysis, Lake Powell further up the Colorado is also well below its original and designed levels and has a similar bathtub ring.
Wetter years may return and partially fill these man-made lakes but unless there are other sources of irrigation water they will never return to their original levels.