Water rights were not allocated centuries ago. All water managements systems (more or less) in place when the US took control of the southwest were overridden and replaced by US-style private property rights, a totally different system than exists east of the 100th parallel/the Mississippi. Consequently, they date back at most 1.5 centuries, and in general, less than that.

The main agreement affecting the SW today is the Colorado River Compact, which dates back only the 1930s/40s. It is far, far from ancient history, and was demonstrably created in a state of willful ignorance of actual precipitation patterns in the region.

Congress can use eminent domain to untangle them.

> Geoengineering. I know that if they won’t do it someone will.

that's true for any terrible idea. in many way's terrible ideas is how humanity progresses. but it seems bad to double down on the same old ("more engineering") to solve the problem. Guess the alternative "spend less" is very unpopular because it's something anyone can do but it actually hurts.

Do you even know what you're talking about? Are you referring to iron rust being randomly distributed in the ocean or along the coast? All that will do is cause an algal bloom and die off, killing off even more of the depleted marine life. That won't sequester any carbon, at best 0.05% if you do it in a way that forms the sediment. Otherwise, you're just killing what little marine life is left for giggles.