[fakethenews2022]

California already has a version of this. It is called the California Aqueduct. It takes water in the north and sends it to the south.

https://en.m.wikipedia.org/wiki/California_Aqueduct

You can see a portion of it driving on I-580.

The problem is that Northern California hasn't been getting enough water either. The rains have been falling further north. Think Seattle.

Also the aqueduct is fed from the existing river system. The major rivers in Oregon and Washington don't go into California AFAIK.

Looks like you would have to divert the Columbia River. Haha.