Earlier quoted context omitted.
If the cities weren’t built up the agricultural water users would likely just use more water. They account for 80% of California’s use.
Most of that watershed is also theirs. The cities have taken more and more of it. They can drive the farmers away, that is an option - then they'll have high food prices _and_ drought.
The most legal solution to the legal shortfalls would likely for the right holders to go sue fossil fuel companies.