[carlob]

> So are you claiming there is some systematic net movement of water out of California and into other states/countries?

Not OP.

The argument made in Cadillac Desert is pretty much the opposite: in order to irrigate California and to give drinking water to its inhabitants, we have damned and diverted many rivers elsewhere with some very large ecological effects.

Another thing to take into account is the salinization of soil as an effect of irrigation: every time water evaporates it leaves behind a salt deposit. This is a process we don't know how to revert and it's considered to be an important historical factor in the rise and fall of civilizations, migration patterns etc.