Adjusting our meat consumption has a huge effect on agricultural water usage as well.
In addition to this, we can also think about overall energy efficiency of consuming a product itself. For instance, potatoes yield more energy and protein than most crops grown.
Given the situation, if we want food we will have to pay the price in terms of water and land for producing the product used to produce that food.
The price subsidy encourages overconsumption, which causes the shortage.
Most places raise prices to fund desalination plants (if they have access to large bodies of water near the population centers, like California does), but that's why they don't. And given they won't do the obviously ideal strategy that works for everyone else in the world, it's been hard to get money from the struggling general budget to build the facilities. Why should every other department struggling for a budget to meet basic needs lose their chance because they won't adopt a simple price structure change?
Instead, non-renewable reserves are being depleted, as mentioned in the article.
The problem here isn't really technical in nature, though.
If the problem for California is one of policy, what endeavors can technology take on to help?
Improve water distribution in soil (I think there is a way to optimize this, varying by soil type and many other factors, that would minimize runoff). Or, get easier systems to recycle runoff. Ideally something with no/few moving or manufactured parts.
Reduce the cost of desalination plants and create a more realtime water market. Having one single water market would be a fundamentally technical task (albeit a complex one), but would level out prices, removing the incentive to make the policy mistakes.
Soil's water holding capacity can be increased through techniques like green mature and cover cropping. The permaculture approach to water is to slow it, spread it, and sink it.
There are also parts of the world where crop production doesn't make sense due to poor soil, erosion, water, climate, etc. Animal husbandry with good management practices is important and can help improve the functioning of these ecosystems. Now, whether we decide to eat these animals is another question.