California is next to the ocean, so if we really wanted to secure the water supply we have technological answers available. Nuclear desalination has been used at scale across the globe for decades, and it's not hard to imagine a less centralized solution powered by solar or wind. https://www.iaea.org/topics/non-electric-applications/nuclea...
Oh the typical techie solution to environmental problems. We can solve this with tech! Wait until the aquifers under North America run dry. That's where most irrigation pump up their ground water from. A few dry rivers and smaller lakes are nothing compared to what's going to happen. Forget your desalination plants. https://en.wikipedia.org/wiki/List_of_aquifers_in_the_United... And it's entirely predictable. In fact…
In this case, yes, we literally can solve this with tech. We don't have to wait for the aquifers to dry up, because California has a ludicrously long coastline just begging for desalination plants up the wazoo.