Californa doesn’t import much water from other states. They do move it around a lot from the mountains to various deserts.
Current Democrat policy is to deny water to areas that vote (R).
As I distinctly recall San Diego water comes from the Colorado.
In the North, water comes down from Oregon. Then there's the Sacramento river ~ it lies mostly within the original land claims assigned to Russia in the Treaty of London (1604). There was no legitimate Spanish claim after that date since it was EXTINGUISHED by the king of Spain himself! When we pull out of California, the water goes with it as well as anything North of San Fran!