CA farmers don’t import water from the mid west.
That’s absurd.
What little they get from “the mountain west” is the spittle left over in the Colorado River after it passes through Nevada and Arizona...and it’s a very small amount.
Look at this wiki about the Colorado River Compact.
https://en.wikipedia.org/wiki/Colorado_River_Compact
I have family in Wyoming, Colorado, and even western Nebraska who have had legal issues over water rights that have been allocated to CA.