At home one can cut showers from 15 mins down to 5 or two. On the farm it means not planting x acres that year.
Without water, locavores will have to become televores. Calif produces food for the whole nation. So while as a percentage of economic output farming is relatively small, as a percentage of food production it's high and thus critical to maintain viability.
The Japanese expend enormous resources on keeping their rice farmers viable in the face of cheaper alternatives, but, in some ways they have a point. Without your farmers you starve.
Yes, farmers should try to use water more efficiently and the gov should encourage that adoption via stick and carrot, but vilifying farmers is not the way to go.
And, this should have been started years ago. Not just now. Surprise, your water is cut, sorry for not preparing you for this via policy!